CHAPTER 39. GRAMINEAE

The Gramineae comprise roughly 10000 species of herbaceous and sometimes woody plants within more than 600 genera. It is the most important of the plant families for man providing cereals, forage and fodders, sugar, construction materials, oils, and many other useful products. Consequently this chapter is substantially longer than other chapters.

In Gramineae the term seed is applied to a wide range of fruiting bodies. The basic component is the caryopsis, the single-seeded fruit: this may be naked (e.g. Triticum aestivum L.) or, more commonly, enclosed within other flower structures. The number and type of other structures which may enclose the caryopses are dependent upon how they become detached from the parent plant and the point of abscission. In many grasses abscission occurs in the spikelet-axis beneath the glumes: thus the caryopses are enclosed within the glumes. The following types of dispersal units may be observed in different species.

1. The caryopsis only.

2. The caryopsis loosely or tightly enclosed within the lemma and palea (a floret).

3. One or more florets enclosed within several glumes and bracts (a spikelet).

4. A cluster of spikelets.

See Chapter 3 (Volume I) for more information on seed development and morphology. In gene banks, the most important morphological feature is to confirm that dispersal units tested for germination do in fact contain a seed (see Chapter 8, Volume I).

Almost all Gramineae are known to exhibit orthodox seed storage characteristics. Two possible exceptions have been reported, viz: Glyceria striata Hitche (manna grass) and Zizania aquatica L. (wild rice). Whilst these species must be treated as recalcitrant seeds for the present, both species are known to exhibit considerable seed dormancy and it is possible that the species may, in fact, possess orthodox seeds and that dormancy and viability have been confused in the past. Some support for this assertion is provided in this chapter for the genus Zizania.

SEED DORMANCY AND GERMINATION

The seeds are endospermic and can show considerable dormancy. Part, but not all, of the problem of germinating the seeds may be associated with the seed covering structures. Typical treatments to overcome dormancy include pre-chilling, alternating temperatures, potassium nitrate and removal of the seed covering structures. Detailed information on seed germination and dormancy-breaking treatments is provided in this chapter for the 42 genera listed in Table 39.1. The table of genera is divided into their respective tribes since there may be some advantage to consult the information provided for closely related genera as well as for the genus of immediate concern. In addition Table 39.1 indicates whether the information on each genus includes information for species with synonyms in other genera. Table 39.2 provides a summary of recommendations for germination test procedures and dormancy-breaking treatments for other species. In addition the algorithm below may be useful in developing suitable germination test procedures for other species for which no information is provided here and for difficult accessions of all graminaceous species.

RBG Kew Wakehurst Place algorithm

Comment on, and an explanation of, the Gramineae algorithm have been provided in Chapter 17. Since that comment includes several alternative suggestions the reader is urged to read the appropriate section of Chapter 17 before attempting to follow this algorithm.

The first and second steps of the algorithm are dependent upon each accession's origin. In the first step of the algorithm accessions of temperate origin are tested at constant temperatures of 16°C and 21°C, whilst those of tropical origin are tested at constant temperatures of 21°C and 26°C. If an accession's origin is unknown or doubtful, test at all three constant temperatures, viz: 16°C, 21°C and 26°C. In all cases light is applied for 12h/d. If the results of these initial tests show a trend in the response of germination to constant temperatures (but full germination has not been achieved) then carry out further tests at more extreme constant temperatures. For example, if the germination of a temperate accession is greater at 16°C than at 21°C, then test further samples of seeds at constant temperatures of 6°C and 11°C with light applied for 12h/d.

If the first step of the algorithm has not resulted in full germination then the second step is to test a further sample of seeds in an alternating temperature regime: 23°/9° (12h/12h) for accessions of temperate origin; 33°/19°C (12h/12h) for accessions of tropical origin; in each case light is applied for 12h/d during the period spent at the upper temperature of each cycle. If an accessions' origin is unknown or doubtful then test a sample of seeds in each alternating temperature regime.

If the second step of the algorithm has not resulted in full germination then the third step is to co-apply 10^-3 M potassium nitrate to the germination test substrate and test in the most successful temperature regime determined from the results of steps one and two.

If the third step of the algorithm has not resulted in full germination then the fourth step is to remove - in part or all - the seed covering structures from a fresh sample of seeds and then test in the most successful regime determined from the results of steps one to three. The actual treatment to the seed covering structures will be dependent upon the morphology of the dispersal units. Where possible extract each caryopsis from the floret (where this is the dispersal unit) and the lemma and palea (if present). This may not be easy for very small seeds, in which case the end of the dispersal unit opposite to the embryo can be chipped or cut away to expose the endosperm. In some cases the lemma and palea adhere very tightly to the caryopsis and their removal can be difficult - and possibly damaging. If this is the case then puncture the seed covering structures and the endosperm in the vicinity of the embryo. The removal of the lemma and palea, in particular, may be easier once the seeds have imbibed.

If the fourth step of the algorithm has not resulted in full germination then the fifth step of the algorithm is to pre-chill the seeds at 2° to 6°C for 8w and then test for germination in the most successful regime determined from the results of steps one to four. If this includes a requirement to remove the seed covering structures this may be easier to accomplish after the pre-chill treatment, but may be more effective in promoting germination if carried out before the pre-chill treatment.

If full germination has still not been promoted, the sixth step of the algorithm is to estimate viability using a tetrazolium test (see Chapter 11, Volume 1).

If the result of the tetrazolium test indicates that the failure to achieve full germination is due to the presence of dead seeds and that one of the above regimes promoted the germination of all, or almost all, the viable seeds, then this regime is used for all subsequent germination tests. If, however, the result of the tetrazolium test indicates that dormancy has not been broken by the regimes applied so far in the algorithm, then experiment with modifications to the above regimes. Clues to possible satisfactory dormancy-breaking treatments and promotory germination test environments can be obtained from the information provided for 42 genera in this chapter. A glance at Table 39.2, however, will provide an initial indication of likely suitable treatments.

TABLE 39.1 List of genera by tribe within the Gramineae for which detailed information on seed germination procedures and dormancy-breaking treatments is provided in this chapter.

TRIBE and Genus		Synonyms
ANDROPOGONEAE
	- Andropogon
	- Bothriochloa
	- Cymbopogon
	- Saccharum
	- Sorghastrum
	- Sorghum	Andropogon, Holcus
	- Themeda
	- Zea	Euchlaena
ARISTIDEAE
	- Aristida
ARUNDINARIEAE
	- Sasa	Bambusa
AVENEAE
	- Agrostis
	- Avena
	- Phleum
BROMEAE
	- Bromus
CHLORIDEAE
	- Bouteloua
	- Chloris
	- Cynodon	Panicum
ERAGROSTIDEAE
	- Eleusine	Cynosurus
	- Eragrostis	Poa
ORYZEAE
	- Oryza
	- Zizania
PANICEAE
	- Brachiaria	Panicum
	- Digitaria
	- Echinochloa	Panicum
	- Panicum
	- Paspalum
	- Pennisetum	Panicum
	- Setaria	Chaetochloa, Panicum
PHALARIDEAE
	- Phalaris
POEAE
	- Dactylis
	- Festuca	Vulpia
	- Lolium
	- Poa
STIPEAE
	- Oryzopsis
	- Stipa
TRITICEAE
	- Aegilops	Triticum
	- Agropyron
	- Hordeum
	- Secale
	- Triticale
	- Triticum
ZOYSIEAE
	- Zoysia	Agrostis

TABLE 39.2 Summary of germination test recommendations for species within the Gramineae

Species and Authority	Substrate	Temperature	Duration	Additional directions	Source
Alopecurus pratensis L.	TP	20°/30°C; 15°/25°C; 10°/30°C	14d	pre-chill, potassium nitrate	ISTA
	TP	20°/30°C	14d	light	AOSA
Alysicarpus vaginalis (L.) DC.	BP	35°C	21d	pierce the seed coats and continue test for a further 5d if (reversible) hard seeds have begun to imbibe, or test swollen seeds at 20°C, 48h, then 35°C, 3d	AOSA
Anthoxanthum odoratum L.	TP	20°/30°C	14d		ISTA
	TP	20°/30°C	14d	light	AOSA
Arrhenatherum elatius (L.) Beauv.	TP	20°/30°C	14d	pre-chill	ISTA
	TP	20°/30°C	14d	light	AOSA
Axonopus affinis Chase	TP	20°/35°C	21d	potassium nitrate, light	ISTA/AOSA
Axonopus compressus (Sw.) Beauv.	TP	20°/35°C	21d	potassium nitrate, light	ISTA
Beckmannia eruciformis (L.) Host	TP	20°/30°C	21d		ISTA
Briza maxima L.	TP	20°/30°C	21d	pre-chill	ISTA
Buchloe dactyloides (Nutt.) Engelm. (burs)	TP; S	20°/35°C	28d	light, potassium nitrate, pre-chill, 5°C, 6w, then test for 14d	AOSA
(caryopses)	TP	20°/35°C	14d	light, potassium nitrate	AOSA
Calamagrostis canadensis (Michx.) Nutt.	TP	15°/25°C	21d	light, potassium nitrate, pre-chill, 5°C, 5d	AOSA
Cenchrus ciliaris L.	TP; S	20°/35°C; 20°/30°C; 30°C	28d	pre-dry, pre-chill, potassium nitrate	ISTA
	S	30°C	28d	light, press fascicles into well packed soil, then pre-chill, 5°C, 7d	AOSA
(caryopses)	TP	30°C	21d	pre-chill, 5°C, 7d, after test scratch firm seeds and continue test, 7d	AOSA
Cenchrus setigerus Vahl	TP	20°/35°C	14d	pre-dry (40°C), potassium nitrate	ISTA
Cynosurus cristatus L.	TP	20°/30°C	21d	pre-chill, potassium nitrate	ISTA
	TP	20°/30°C	21d	light, pre-chill, 5°C or 10°C, 3d	AOSA
Coix lacrima-jobi L.	BP	20°/30°C	21d		ISTA
	BP	20°/30°C	16d	very sensitive to low temperatures	AOSA
Deschampsia caespitosa (L.) Beauv.	TP	20°/30°C; 20°C	16d	pre-chill, potassium nitrate	ISTA
Deschampsia flexuosa (L.) Trin.	TP	20°/30°C; 20°C	16d	pre-chill, potassium nitrate	ISTA
Dichanthium aristatum (Poir.) C.E. Hubbard	TP	20°/35°C	21d	potassium nitrate	ISTA
Ehrharta calycina Smith	TP	20°C	21d	pre-chill	ISTA
	TP	10°/30°C	28d	light	AOSA
Elymus canadensis L.	TP	15°/30°C	21d	light, pre-chill, 5°C, 2w	AOSA
Elymus junceus Fisch.	TP	20°/30°C	14d	pre-chill	ISTA
	TP	20°/30°C	14d	light, pre-chill, 5°C or 10°C, 5d	AOSA
Holcus lanatus L.	TP	20°/30°C	14d	pre-chill, potassium nitrate	ISTA
	TP	20°/30°C	14d	light	AOSA
Melinis minutiflora Beauv.	TP	20°/30°C	21d	pre-chill, potassium nitrate	ISTA
	TP	20°/30°C	21d	light	AOSA
Schizachyrium scoparium (Michx.) Nash	TP; S	20°/30°C	28d	light, potassium nitrate, pre-chill, 5°C, 2w	AOSA
Sporobolus cryptandrus (Torr.) Gray	TP	5°/35°C; 15°/35°C	28d	light, potassium nitrate, pre-chill, 5°C, 4w	AOSA
Trisetum flavescens (L.) Beauv.	TP	20°/30°C	21d	pre-chill, potassium nitrate	ISTA
Urochloa mosambicensis (Hack.) Dandy	TP	20°/35°C	21d		ISTA

AEGILOPS

A. cylindrica Host [Triticum cylindricum Ces., Pass. & Gib.]
A. Kotschyi Boiss.
A. ovata L.
A. triuncialis	barb goatgrass

I. Evidence of dormancy

Freshly harvested seeds of Aegilops spp. show considerable dormancy (1-10, 12). Seeds of A. triuncialis require 3 to 4 months after-ripening for full germination (3), whereas after-ripening seeds of A. ovata for 1 year did not entirely remove dormancy (2).

II. Germination regimes for non-dormant seeds

A. cylindrica

Constant temperatures: 20°C, dark (4)

A. Kotschyi

Constant temperatures: 20°C, dark (6,7,8,12)

A. ovata

Constant temperatures: 20°C in light, 150-250 fc (1)

III. Unsuccessful dormancy-breaking treatments

A. cylindrica

Constant temperatures: 30°C, 35°C (4)

Potassium nitrate: co-applied, 0.1, 1 g/1, at 10°C, 15°C, 20°C (4)

GA₃: co-applied, 1000 ppm, at 10°C, 15°C (4)

A. kotschyi

Constant temperatures: 30°C (5)

Pre-dry: (6)

Auxin: co-applied, 50 ppm, at 20°C (8)

Cytokinin: co-applied, 50 ppm, at 20°C (8)

A. ovata

Constant temperatures: 35°C, 40°C, in light or dark (1)

IV. Partly-successful dormancy-breaking treatments

A. cylindrica

Constant temperatures: 10°C, 28d (4)

A. kotschyi

Constant temperatures: 5°C (5)

GA₃: co-applied, 50 ppm, at 20°C (8); co-applied, 10-100 ppm (11)

Removal of seed covering structures: dehull (5,6,8,11)

A. ovata

Constant temperatures: 5°C in light or dark (1); 10°C, dark (1); 15°C, 20°C, 25°C, light, 16d (1,2)

V. Successful dormancy-breaking treatments

A. cylindrica

Constant temperatures: 15°C, 20°C, 28d (4)

GA₃: co-applied, 1000 ppm, at 20°C (4)

A. kotschyi

Removal of seed covering structures: dehull, germinate at 5°C (5); dehull, plus GA₃, co-applied, 10-100 ppm (11)

GA₃: co-applied, 50 ppm (10); co-applied, 50 ppm, plus RNAase, 10g/ml, co-applied (10)

A. ovata

Constant temperatures: 10°C in light, 150-250 fc (1)

Removal of seed covering structures: dehull (1)

VI. Comment

We suggest that a constant temperature of between 5° and 10°C combined, where necessary, with removal of the seed covering structures should be satisfactory for testing accessions of Aegilops spp. for germination.

VII. References

1. Datta, S.C., Evenari, M. and Gutterman, Y. (1970). The heteroblasty of Aegilops ovata L. Israel Journal of Botany, 19, 463-483.

2. Datta, S.C., Gutterman, Y. and Evenari, M. (1972). The influence of the origin of the mother plants on yield and germination of their caryopses in Aegilops ovata. Planta, 105, 155-164.

3. Laude, H.M. (1956). Germination of freshly harvested seeds of some western range species. Journal of Range Management, 9, 126-129.

4. Morrow, L.A., Young, F.L. and Flom, D.G. (1982). Seed germination and seedling emergence of jointed goatgrass (Aegilops cylindrica). Weed Science, 30, 395-398.

5. Waisel, Y. and Adler, Y. (1959). Germination behavior of Aegilops Kotschyi Boiss. Canadian Journal of Botany, 37, 741-742.

6. Wurzburger, J. and Koller, D. (1973). Onset of seed dormancy in Aegilops Kotschyi Boiss. and its experimental modification. New Phytologist, 72, 1057-1061.

7. Wurzburger, J. and Koller, D. (1976). Differential effects of the parental photothermal environment on development of dormancy in caryopses of Aegilops Kotschyi. Journal of Experimental Botany, 27, 43-48.

8. Wurzburger, J. and Leshem, Y. (1967). Gibberellin and hull controlled inhibition of germination in Aegilops Kotschyi Boiss. Israel Journal of Botany, 16, 181-186.

9. Wurzburger, J. and Leshem, Y. (1969). Physiological action of the germination inhibitor in the husk of Aegilops Kotschyi Boiss. New Phytologist, 68, 337-341.

10. Wurzburger, J. and Leshem, Y. (1971). Ribonucleic acid as an inducer of germination inhibition in Aegilops Kotschyi. Plant and Cell Physiology, 12, 211-215.

11. Wurzburger, J. and Leshem, Y. (1974). The role of gibberellin and the hulls in the control of germination in Aegilops Kotschyi caryopses. Canadian Journal of Botany, 52, 1597-1601.

12. Wurzburger, J., Leshem, Y. and Koller, D. (1976). Correlative aspects of imposition of dormancy in caryopses of Aegilops Kotschyi. Plant Physiology, 57, 670-671.

AGROPYRON

A. cristatum (L.) Gaertn.	fairway crested
A. dasystachyum (Host) Scribn.	thickspike wheatgrass wheatgrass
A. desertorum Fisch. ex Link	standard crested wheatgrass
A. elongatum (Host) Beauv.	tall wheatgrass
A. intermedium (Host) Baumg.	intermediate wheatgrass
A. repens (L.) Beauv.	quackgrass
A. riparium Scribn. & Smith	streambank wheatgrass
A. semicostatum
A. siberian Willd.	Siberian wheatgrass
A. smithii Rydb.	Western wheatgrass
A. spicatum (Pursh) Scribn. & Smith	bluebunch or beardless wheatgrass
A. trachycaulum (Link) H.F. Lewis	slender wheatgrass
A. trichophorum Link	pubescent wheatgrass

I. Evidence of dormancy

Severe dormancy has been reported in seed lots of A. repens (6, 7, 16), A. semicostatum (13), A. trachycaulum (13), A. interm edium (20), A. cristatum (1,8,9,20), A. siberian (20), A. trichophorum (20), A. smithii (2-4,10,12,15,18,20) and A. spicatum (2 0). Secondary dormancy has been induced: in A. elongatum where moist seeds experienced sub-zero temperatures before harvest (17); in A. smithii where seeds wer e pre-chilled at 10°C for 5 days (3); and in A. smithii where imbibed seeds were exposed to high constant temperatures (18).

II. Germination regimes for non-dormant seeds

A. cristatum, A. desertorum

TP: 15°/25°C; 20°/30°C (16h/8h): 14d (AOSA, ISTA)

A. elongatum

TP: 15°/25°C; 20°/30°C (16h/8h): 21d (ISTA)

TP: 15°/25°C (16h/8h): 21d (AOSA)

A. intermedium

TP: 15°/25°C; 20°/30°C (16h/8h): 28d (AOSA, ISTA)

A. repens

TP: 10°/30°C; 20°/30°C (16h/8h): 21d (ISTA)

A. smithii

TP; BP: 15°/25°C; 20°/30°C (16h/8h): 28d (ISTA)

TP; BP: 15°/30°C (16h/8h): 28d (AOSA)

A. spicatum

TP; BP: 15°/25°C (16h/8h): 14d (AOSA)

A. trachycaulum

TP: 15°/25°C; 20°/30°C (16h/8h): 14d (ISTA)

TP: 20°/30°C (16h/8h): 14d (AOSA)

A. trichophorum

TP: 15°/25°C; 20°/30°C (16h/8h): 28d (AOSA,ISTA)

III. Unsuccessful dormancy-breaking treatments

A. desertorum

Potassium nitrate: co-applied, 0.2% (13)

A. smithii

Potassium nitrate: co-applied, 0.2% (13)

Thiourea: co-applied, 0.2% (13)

GA₃: co-applied, 100 ppm (13)

Light: white (10); white, 9h/d (3,4,15); incandescent, 22 lux, continuous (18); red, 15 min (15); far red, 1300 lux, intermittent (18)

A. trachycaulum

Potassium nitrate: co-applied, 0.2% (13)

Thiourea: co-applied, 0.2% (13)

GA₃: co-applied, 100 ppm (13,14)

IV. Partly-successful dormancy-breaking treatments

A. cristatum

Alternating temperatures: 15°/25°C, 10°/20°C, 10°/25°C, 10°/30°C, 15°/20°C, 15°/30°C, 20°/25°C, 20°/30°C (16h/8h) (20); 20°/30°C (16h/8h) (8); 20°/30°C (18h/6h) (9)

Pre-chill: 6°-8°C, 4d, germinate at 20°C (8); 10°C, 7d, germinate at 20°/30°C (16h/8h) in light (1)

A. desertorum

Constant temperatures: 20°C (14)

Light: (13,14)

GA₃: co-applied, 100 ppm (14)

A. elongatum

Pre-chill: 5°C, 5d, plus potassium nitrate, co-applied, germinate at 20°/30°C (16h/8h) in light (17)

A. intermedium

Alternating temperatures: 10°/25°C, 15°/25°C, 20°/25°C, 15°/20°C (16h/8h) (20)

A. repens

Alternating temperatures: (16); 15°/30°C (15h/9h) (6); 25°/30°C (16h/8h) in light (20)

Removal of seed covering structures: dehull (19)

A. semicostatum

Pre-chill: (13)

A. siberian

Alternating temperatures: 15°/25°C, 5°/20°C, 5°/25°C, 10°/20°C, 10°/25°C, 15°/20°C (16h/8h) (20)

A. smithii

Alternating temperatures: 15°/25°C, 15°/30°C (20h/4h) (18); 15°/40°C, 20°/40°C, 25°/40°C (16h/8h) (20); 15°/30°C (16h/8h) (12, 15); 20°/30°C, 20°/35°C (18h/6h) (10)

Pre-chill: (13); 8°-10°C, 14°-17°C, 6d, germinate at 20°/30°C (16h/8h) (10)

Light: dark, continuous (3); red, 4,8 min (15); red, 13000 lux, 3,5 min (18)

Potassium nitrate: co-applied, 0.2%, at 15°/30°C (16h/8h) (2,4,12); pre-applied, 24h, 0.2% (15)

Ethylene chlorohydrin: pre-applied, 24h, 750, 1250 ppm (3,4)

GA₃: co-applied, 10^-3 M, plus kinetin, co-applied, 0.5 M (18); pre-applied, 24h, 100 ppm (15)

Kinetin: pre-applied, 24h, 100 ppm (15)

A. spicatum

Alternating temperatures: 15°/20°C, 20°/25°C (16h/8h) (20)

A. trachycaulum

Constant temperatures: 0°-40°C (20)

Alternating temperatures: 15°/25°C, 15°/30°C, 20°/30°C, 20°/35°C (16h/8h) (20)

Pre-chill: (13)

Light: (13)

A. trichophorum

Alternating temperatures: 15°/25°C, 15°/30°C (16h/8h) (20)

V. Successful dormancy-breaking treatments

A. cristatum

Pre-chill, Potassium nitrate (ISTA)

Light, Pre-chill, Potassium nitrate (AOSA)

Pre-chill: 8°-10°C, 4-6d (9); 10°C, 7d, plus potassium nitrate, co-applied, 0.2% (1)

A. dasystachyum

Alternating temperatures: 15°/25°C, 15°/30°C, 20°/30°C (16h/8h) (20)

A. desertorum

Pre-chill, Potassium nitrate (ISTA)

Light, Pre-chill, Potassium nitrate (AOSA)

Alternating temperatures: 15°/30°C (13); 15°/25°C, 10°/25°C (16h/8h) (20)

Pre-chill: (13)

Potassium nitrate: co-applied, 0.2% (13)

Thiourea: co-applied, 0.2% (13)

GA₃: co-applied, 100 ppm (13,14)

A. elongatum

Pre-chill, Potassium nitrate (ISTA)

Light, Pre-chill, Potassium nitrate (AOSA)

Constant temperatures: 8°C, 14°C (11)

Alternating temperatures: 15°/25°C, 15°/30°C (16h/8h) (20)

Pre-chill: 5°C, 5d, plus potassium nitrate, co-applied, 0.2%, germinate at 20°/30°C (16h/8h) in light, then pierce ungerminated seeds which remain (17)

Potassium nitrate: co-applied, 0.2%, germinate at 15°/30°C (16h/8h) and pierce ungerminated seeds which remain (17)

A. intermedium

Pre-chill, Potassium nitrate (ISTA)

Light (AOSA)

A. repens

Pre-chill, Potassium nitrate (ISTA)

Alternating temperatures: 20°/30°C in light, 25°/20°C (16h/8h) (19)

A. semicostatum

Alternating temperatures: 15°/30°C (16h/8h) (13)

Pre-chill: (13)

A. smithii

Pre-chill, Potassium nitrate (ISTA)

Potassium nitrate, test in soil (AOSA)

Alternating temperatures: 15°/30°C (13)

Removal of seed covering structures: expose embryo, germinate at 15°/30°C (16h/8h) in dark (2,3,4)

GA₃: co-applied, 10^-3 M, plus kinetin, 0.5 M, germinate at 15°/25°C (20h/4h) in light, 13000 lux, 4h/d (18)

A. spicatum

Light, Pre-chill, Potassium nitrate (AOSA)

Constant temperatures: 20°C (5)

A. trachycaulum

Pre-chill, Potassium nitrate (ISTA)

Pre-chill, repeat Pre-chill, then test at 20°/30°C, 4d (AOSA)

Alternating temperatures: 15°/30°C (16h/8h) (13); 15°/25°C, 15°/30°C, 20°/30°C, 20°/35°C (16h/8h) (20)

A. trichophorum

Pre-chill, Potassium nitrate (ISTA)

Light (AOSA)

VI. Comment

It is essential that seeds of Agropyron spp. be provided with alternating temperature regimes for germination (13,15,16,18-20). In general alternating temperature regimes of 15°/25°C or 20°/25°C (16h/8h) appear to be suitable for accessions of Agropyron spp. with the possible exception of A. smithii where the temperature during the 8h cycle may have to be as high as 40°C (20), but the use of alternating temperature regimes alone is unlikely to be sufficient to promote full germination in all Agropyron accessions. For most Agropyron spp. the ISTA and AOSA recommendations for breaking dormancy suggest that potassium nitrate and pre-chilling treatments also be applied. For A. smithii treatment with potassium nitrate, only, is recommended in an alternating temperature regime of 15°/30°C (16h/8h). This regime, however, is not completely successful in promoting germination (2,4,12,15), but full germination can be promoted by careful removal of the seed covering structures, pricking and testing in alternating temperature regimes (2-4,12,17,19). Some labour can be avoided by removing the seed covering structures and/or pricking only those seeds which have failed to germinate after between 10 and 28 days in an alternating temperature germination test regime. Attention is drawn to the multifactor procedure outlined above for A. elongatum (17) - combining pre-chilling (5°C, 5 days), potassium nitrate (co-applied, 0.2%), pricking and testing at 20°/30°C (16h/8h) - which may be more widely applicable. Care is required with the light environment since light can inhibit the germination of some seed lots of A. repens, A. semicostatum, and A. smithii (2-4,10,13-16,18).

VII. References

1. Andersen, A.L. and Drake, V.C. (1944). Preliminary study of seed of crested wheatgrass exhibiting delayed germination. Proceedings of the Association of Official Seed Analysts, 35, 146-152.

2. Bass, L.N. (1955). Determining the viability of Western wheatgrass seed lots. Proceedings of the Association of Official Seed Analysts, 45, 102-104.

3. Delouche, J.C. (1956). Dormancy in seeds of Agropyron smithii, Digitaria sanguinalis and Poa pratensis. Iowa State Colle Journal of Science, 30, 348-349.

4. Delouche, J.C. and Bass, L.N. (1954). Effect of light and darkness upon the germination of seeds of western wheatgrass Agropyron smithii L. Proceedings of the Association of Official Seed Analysts, 44, 104-113.

5. Evans, G.R. and Tisdale, E.W. (1972). Ecological characteristics of Aristida longiseta and Agropyron spicatum in West-Central Ida Ecology, 53, 137-142.

6. Everson, L.E. (1954). The germination of mature and immature seeds of quackgrass (Agropyron repens). Proceedings of the Association of Official Seed Analysts, 44, 127-128.

7. Grime, J.P., Mason, G., Curtis, A.V., Redman, J., Band, S.R., Mowforth, M.A.G., Neal, A.M. and Shaw, S. (1981). A comparative study of germination characteristics in a local flora. Journal of Ecology, 69, 1017-1059.

8. Hay, W.D. (1936). Germination of crested wheatgrass (Agropyron cristatum): preliminary studies. Proceedings of the Association of Official Seed Analysts, 28, 66-70.

9. Hay, W.D. (1936). Further studies with the germination of crested wheatgrass. Proceedings of the Association of Official Seed Analysts, 28, 86-88.

10. Hay, W.D. (1939). Laboratory germination studies with Agropyron smithii. Preliminary results. Proceedings of the Association of Official Seed Analysts, 30, 244-245.

11. Hunt, O.J. (1961). Low-temperature germination, a possible strain response of tall wheatgrass, Agropyron elongatum (Host.) Beauv. Agronomy Journal, 53, 277.

12. Kinch, R.C. (1963). A method of inducing rapid germination of Western wheatgrass. Proceedings of the Association of Official Seed Analysts, 53, 55-57.

13. Nakamura, S. (1962). Germination of grass seeds. Proceedings of the International Seed Testing Association, 27, 710-729.

14. Nakamura, S., Watanabe, S. and Ichihara, J. (1960). Effect of gibberellin on the germination of agricultural seeds. Proceedings of the International Seed Testing Association, 25, 433-439.

15. Schultz, Q.E. and Kinch, R.C. (1976). The effect of temperature and growth promoters on seed dormancy in Western wheatgrass seed. Journal of Seed Technology, 1, 79-85.

16. Thompson, K., Grime, J.P. and Mason, G. (1977). Seed germination in response to diurnal fluctuations of temperature. Nature, 267, 147-149.

17. Thornton, M.L. (1966). Seed dormancy in tall wheatgrass (Agropyron elongatum). Proceedings of the Association of Official Seed Analysts, 56, 116-119.

18. Toole, V.K. (1976). Light and temperature control of germination in Agropyron smithii seeds. Plant and Cell Physiology, 17 1263-1272.

19. Williams, E.D. (1968). Preliminary studies of germination and seedling behaviour in Agropyron repens (L.) Beavu. and Agrostis gigantea Roth. Proceedings of the 9th British Weed Control Conference, Vol.1, 119-124.

20. Young, J.A. and Evans, R.A. (1982). Temperature profiles for germination of cool season range grasses. USDA, Agriculture Research Service, Agriculture Research Results, Western Series, No. 27.

AGROSTIS

A. canina L.	velvet bentgrass
A. capillaris
A. gigantea Roth.	redtop
A. stolonifera L. [A. alba Auth.; A. maritima Lam.; A. palustris Huds.]	creeping bentgrass
A. tenuis Sibth. [A. capillaris Huds.; A. vulgaris With.]	colonial bentgrass

I. Evidence of dormancy

Freshly harvested seeds of Agrostis spp. can be very dormant (1-3,5,6,8,9,11,13-17). Between 6 and 8 months after-ripening may be required to remove dormancy (8,16), whilst seeds of A. capillaris stored for 41-44 weeks at 10°C remained dormant (17). Secondary dormancy was induced in imbibed seeds of A. capillaris exposed to an alternating temperature regime of 10°/20°C (12h/12h) in the dark (17).

II. Germination regimes for non-dormant seeds

A. canina

TP: 15°/25°C; 20°/30°C; 10°/30°C (16h/8h): 21d (ISTA)

TP: 20°/30°C (16h/8h): 21d (AOSA)

A. gigantea

TP: 15°/25°C; 20°/30°C; 10°/30°C (16h/8h): 10d (ISTA)

TP: 20°/30°C (16h/8h): 10d (AOSA)

A. stolonifera

TP: 15°/25°C; 20°/30°C; 10°/30°C (16h/8h): 28d (ISTA)

TP: 15°/30°C; 10°/30°C; 15°/25°C (16h/8h): 28d (AOSA)

A. tenuis

TP: 15°/25°C; 20°/30°C; 10°/30°C (16h/8h): 28d (ISTA)

TP: 15°/25°C; 15°/30°C; 10°/30°C (16h/8h): 28d (AOSA)

III. Unsuccessful dormancy-breaking treatments

A. capillaris

Constant temperatures: 19°-22°C in dark or light, far red, 1.7 x 10^-6 mol m^-2 s^-1, 10 min (17)

A. gigantea

Constant temperatures: 20°C, dark (16)

Potassium nitrate: co-applied, 0.2% (9)

GA₃: co-applied, 100 ppm (9,10)

A. stolonifera

Constant temperatures: 20°C, dark (8)

A. tenuis

Constant temperatures: 20°C, dark (8); 5°-30°C (13)

Alternating temperatures: 10°/30°C (16h/8h), dark (2); 20°/30°C (16h/8h), dark (8)

IV. Partly-successful dormancy-breaking treatments

A. canina

Alternating temperatures: 15°/20°C (9h/15h) in light, 15h/d (6); 20°/30°C (16h/8h) in light, 5 lux (8)

A. capillaris

Alternating temperatures: 5°-16°/20°C, 23°-30°/20°C (12h/12h) in dark (17)

A. gigantea

Alternating temperatures: 15°/20°C (9h/15h) (6); 20°/30°C (16h/8h) (15); 20°/30°C (16h/8h) in light (9,10); 25°/30°C (16h/8h) in light (16)

Light: at 15°/20°C (9h/15h) (6)

Thiourea: co-applied, 0.2% (9)

A. stolonifera

Alternating temperatures: 15°/20°C (9h/15h) in light (6); 20°/30°C (16h/8h) in light, 50, 200 fc (8): 30°/40°C, 28°/34°C (12h/12h) (4) Light: red (14)

A. tenuis

Alternating temperatures: 10°/30°C, 15°/30°C, 20°/30°C (16h/8h) in light (2,5,8,9,11,14); 10°/30°C, 15°/30°C, 20°/30°C (18h/6h) in light (1,3); 15°/25°C (18h/6h), dark (1,11); 20°/30°C, 10°/26°C, 10°/30°C (18h/6h) (5); 20°/30°C, 5°/15°C (16h/8h) (12)

Pre-chill: 4°C, 2,7d (1); 5°C, 10°C, 33d, germinate at 10°/25°C (12h/12h) (13); 4°C, 10°C, 7d, plus potassium nitrate, co-applied, 0.2%, germinate at 20°/30°C (16h/8h) in light (2)

Warm stratification: 15°C, 20°C, 25°C, 30°C, 33d, germinate at 10°/25°C (12h/12h) (13)

Potassium nitrate: co-applied, 0.2%, at 15°/25°C (18h/6h) in dark (1); co-applied, 0.2%, at 10°/30°C, 20°/30°C (16h/8h) in light (2); co-applied, 0.2%, at 15°/25°C, 15°/30°C (15h/9h) in light (3)

V. Successful dormancy-breaking treatments

A. canina

Pre-chill, Potassium nitrate (ISTA)

Light, Potassium nitrate (AOSA)

Alternating temperatures: 20°/30°C (16h/8h) in light, 50, 200 fc (8)

Potassium nitrate: co-applied, 0.2%, at 20°/30°C (16h/8h) in light (8)

A. capillaris

Alternating temperatures: 5°-16°/20°C (12h/12h) in light, red, 1.4x10^-6 mol m^-2 s^-1, 10 min (17)

Potassium nitrate: co-applied, 2x10^-2, 2x10^-3 M, at 5°-16°/20°C (12h/12h) dark (17)

GA₃: co-applied, 0.144 M, at 5°-16°/20°C in light, red, 1.4x10^-6 mol m^-2 s^-1, 10 min (17)

A. gigantea

Pre-chill, Potassium nitrate (ISTA)

Light, Potassium nitrate (AOSA)

Alternating temperatures: 20°/30°C (16h/8h) in light (15, 16)

Pre-chill: 5°C, 10d (9)

A. stolonifera

Pre-chill, Potassium nitrate (ISTA)

Light, Pre-chill, Potassium nitrate (AOSA)

Alternating temperatures: 20°/30°C, 25°/35°C (16h/8h) (7); 25°/18°C (12h/12h) (4); 15°/25°C (16h/8h) in light (14)

Potassium nitrate: co-applied, 0.2%, at 20°/30°C (16h/8h) in light (8)

A. tenuis

Pre-chill, Potassium nitrate (ISTA)

Light, Pre-chill, Potassium nitrate (AOSA)

Alternating temperatures: 15°/30°C, 15°/35°C, 15°/40°C (16h/8h) (14); 10°/20°C (16h/8h) in light (12); 5°/19°-26°C, 9°-16°/25°C (12h/12h) (13)

Pre-chill: 5°C, 10°C, 33d, plus GA₃, co-applied, 500 ppm, germinate at 10°/25°C (12h/12h) (13); 4°C, 2-7d, plus potassium nitrate, co-applied, 0.2% (1)

Warm stratification: 15°-30°C, 33d, plus GA₃, co-applied, 500 ppm, germinate at 10°/25°C (12h/12h) (13)

Potassium nitrate:co-applied, 0.2%, germinate at 15°/25°C, 15°/30°C, 10°/30°C (16-18h/6-8h) in light (1,2,3,5,8,11)

VI. Comment

Dormant seed accessions of Agrostis spp. require light and alternating temperatures for germination (1-3,6,8,9,11,14-17): additionally potassium nitrate in the germination test medium may be of further benefit (1,8) or avoid the requirement for light (17). A brief, low intensity exposure of the seeds to light can promote germination considerably (2,8,11,17), but higher intensities can reduce the proportion of seeds germinating, e.g. 200 fc, 7.5 hours per day (8). The above tends to suggest that AOSA/ISTA prescriptions and recommendations are satisfactory, but in A. capillaris 10°/20°C (12h/12h) with a brief light treatment has been suggested (17).

VII. References

1. Andersen, A.M. (1944). Germination of freshly harvested seed of Western grown Astoria bentgrass. Proceedings of the Association of Official Seed Analysts, 35, 138-146.

2. Andersen, A.M. (1946). The effect of light, temperature and potassium nitrate on the germination of Agrostis tenuis Sibth. and A. tenu is var. Highland seed. Procedures of the Association of Official Seed Analysts, 36, 112-125.

3. Bass, L.N. (1959). Comparison of germination percentages obtained for highland bentgrass seed tested at different temperature alternations. Proceedings of the Association of Official Seed Analysts, 49, 73-76.

4. Eggens, J.L. and Ormrod, D.P. (1982). Creeping bentgrass, Kentucky bluegrass and annual bluegrass seed germination response to elevated temperature. HortScience, 17, 624-625.

5. Gadd, I. (1955). Germination of seed of New Zealand browntop, Agrostis tenuis Sibth. Proceedings of the International Seed Testing Association, 20, 29-45.

6. Grime, J.P., Mason, G., Curtis, A.V., Rodman, J, Band, S.R., Mowforth, M.A.G., Neal, A.M. and Shaw, S. (1981). A comparative study of germination characteristics in a local flora. Journal of Ecology, 69, 1017-1059.

7. Harrington, G.T. (1923). Use of alternating temperatures in the germination of seeds. Journal of Agricultural Research, 23, 295-33 2.

8. Leggatt, C.W. (1946). Germination of seeds of three species of Agrostis. Canadian Journal of Research, C, 24, 7-21.

9. Nakamura, S. (1962). Germination of grass seeds. Proceedings of the International Seed Testing Association, 27, 710-729.

10. Nakamura, S., Watanabe, S. and Ichihara, J. (1960). Effect of gibberellin on the germination of agricultural seeds. Proceedings of the International Seed Testing Association, 25, 433-439.

11. Pierpoint, M. and Jensen, L. (1958). Activation of germination of Highland bentgrass by infra-red lamp. Proceedings of the Association of Official Seed Analysts, 48, 75-80.

12. Schmidt, B. (1969). [On the influence of temperature at the course of germination of some important lawn grasses.] Saatgut Wirtschaft, 21, 584-589.

13. Schonfeld, M.A. and Chancellor, R.J. (1983). Factors influencing seed movement and dormancy in grass seeds. Grass and Forage Science, 38, 243-250.

14. Toole, V.K. and Koch, E.J. (1977). Light and temperature control of dormancy and germination in bentgrass seeds. Crop Science, 17, 806-811.

15. Williams, E.D. (1968). Preliminary studies of germination and seedling behaviour in Agropyron repens (L.) Beauv. and Agrostis gigante ea Roth. Proceedings of the 9th British Weed Control Conference, Vol. 1, 119-124.

16. Williams, E.D. (1973). Seed germination of Agrostis gigantea Roth. Weed Research, 13, 310-324.

17. Williams, E.D. (1983). Effects of temperature fluctuation, red and far-red light and nitrate on seed germination of five grasses. Journal of Applied Ecology, 20, 923-935.

ANDROPOGON

A. gayanus Kunth	gamba grass
A. furcatus Muhl.	big bluestem
A. gerardii Vitm.	big bluestem
A. gerardii Vitm. x A. hallii Hack.	champ bluestem
A. hallii Hack.	sand bluestem
A. ischaemum L.	bluestem
A. scoparius Michx.	little bluestem

I. Evidence of dormancy

A. furcatus (2), A. gerardii (1,4,8), A. hallii (7) and A. scoparius (2,8) show considerable seed dormancy. For example, seeds of A. hallii and A. gerardii after-ripened for 1 (7) and 4 years (4) respectively remained dormant. Reports of dormancy in A. gayanus conflict: seeds have been reported to show both considerable dormancy (10) and no dormancy (12).

II. Germination regimes for non-dormant seeds

A. gayanus

Alternating temperatures: 25°/35°C (12h/12h) in light, 3.2x10^-6 W cm^-2 (12)

A. gerardii, A. hallii

TP; S: 20°/30°C (16h/8h): 28d (AOSA)

Alternating temperatures: 20°/30°C (16h/8h) in light, fluorescent, 16h/d (5)

III. Unsuccessful dormancy-breaking treatments

A. gayanus

Hydrogen peroxide: co-applied, 1, 1.5 M (10)

A. gerardii

Phosphine: fumigation, 120h, 3920-4720 ppm (9)

A. hallii

Light: 15000 lux, 8,12,16h/d (7) pH: 2.5 (6)

A. ischaemum, A. scoparius

Phosphine: fumigation, 120h, 3920-4720 ppm (9)

IV. Partly-successful dormancy-breaking treatments

A. gayanus

Pre-chill: 5°C, 2w (10)

Potassium nitrate: co-applied, 0.1-0.3% (10)

Hydrogen peroxide: co-applied, 0.5 M (10)

GA₃: co-applied, 250-1000 ppm (10)

Removal of seed covering structures: (10)

A. gerardii

Alternating temperatures: 15°/30°C, 20°/30°C (16h/8h) (1); 10°/20°C (6h/18h) in dark or light, 400-500 fc, 6h/d in 20°C cycle (4);20°/30°C (16h/8h) in light (11)

Pre-chill: 5°-8°C, 2w (1); 5°C, 10°C, 14d (11); then germinate at 20°/30°C (16h/8h) in light, 14d (14); 5°C, 10°C, 14d, plus potassium nitrate, co-applied, 0.2% (11)

GA₃: pre-applied, 24h, 100 ppm (4); pre-applied, 10-500 ppm (8)

Potassium nitrate: co-applied, 0.2% (11)

A. hallii

Constant temperatures: 25°C, 30°C, 35°C (7)

Alternating temperatures: 15°/25°C, 20°/30°C, 25°/35°C (16h/8h) in light or dark (7)

Pre-chill: then germinate at 20°/30°C (16h/8h) in light, 14d (14)

pH: 4-11.5 (6)

Phosphine: fumigation, 120h, 3920-4720 ppm (9)

A. scoparius

GA₃: pre-applied, 10-500 ppm (8)

V. Successful dormancy-breaking treatments

A. gerardii, A. hallii

Light, Pre-chill, Potassium nitrate (AOSA)

VI. Comment

Seeds of A. gayanus are likely to cause the greatest problems of dormancy, but it is important to ensure that the problem of lack of germination is not caused by empty seeds. The following germination test procedures have been recommended as at least partly effective in promoting the germination of dormant seeds of this species: germinate on top of filter papers - moistened optionally with potassium nitrate (probably 0.2%) - at 20°/35°C (presumably 16h/8h) with light for 21 days (3); germinate on top of filter papers moistened with potassium nitrate at 20°/30°C (16h/8h) with light applied for 8 hours per day for 28 days (3).

In a comparison of germination test results from different laboratories with seeds of A. gerardii x A. hallii at 15°/30°C or 20°/30°C (16h/8h) with no pre-chill or a 2 week pre-chill treatment at 5°C, 7°C or 8°C, the regime 20°/30°C after pre-chill at 7°C gave significantly greater germination (1), but the difference was only marginal. The pre-chill treatments were, however, beneficial (1).

Although most of the results for A. hallii were from tests where light was applied for 8 hours per day during the high temperature phase of the alternating temperature cycle (e.g. 6), there is one report of light being applied for 16 hours per day during the low temperature phase of the alternating temperature cycle (5). This is unlikely to be of any particular benefit (7). For this species a constant germination test temperature of 35°C or an alternating temperature regime of 25°/35°C (16h/8h) have been recommended (7).

It is suggested that seeds of Andropogon spp. be tested for germination at 20°/35°C (16h/8h) for at least 28 days with potassium nitrate co-applied at 0.2% and the light regime described in Chapter 6 after a 2-week pre-chill treatment at 5°-7°C. Alternatively removal of the seed covering structures - with subsequent testing at 20°/35°C (16h/8h) in light, 8h/d - can avoid the need to pre-chill and co-apply potassium nitrate (13).

References

1. Atkins, B.A. (1977). Variations on purities, germination and PLS (pure live seed) on champ bluestem. Journal of Seed Technology, 2 40-47.

2. Coukos, C.J. (1944). Seed dormancy and germination in some native grasses. Journal of American Society of Agronomy, 36, 337-345.

3. Ferguson, J.E. (1982). C.I.A.T. (Personal communication).

4. Kucera, C.L. (1966). Some effects of gibberellic acid on grass seed germination. Iowa State Journal of Science, 41, 137-143.

5. Shaidaee, G., Dahl, B.E. and Hansen, R.M. (1969). Germination and emergence of different age seed of six grasses. Journal of Range Management, 22, 240-243.

6. Stubbendieck, J. (1974). Effect of pH on germination of three grass species. Journal of Range Management, 27, 78-79.

7. Stubbendieck, J. and McCully, W.G. (1976). Effect of temperature and photoperiod on germination and survival of sand bluestem. Journal of Range Management, 29, 206-208.

8. Svedarsky, D. and Kucera, C.L. (1970). Effects of gibberellic acid and post-harvest age on germination of prafrie grasses. Iowa State Journal of Science, 44, 513-518.

9. White, G.D. and Jacobson, E.T. (1972). Phosphine fumigation: effects on the germination of grass seed. Journal of Economic Entomology, 65, 1523-1524.

10. Eira, M.T.S. (1983). [Comparison of methods for overcoming seed dormancy in Andropogon grass.] Revista Brasileira de Sementes, 5, 37-49.

11. Faroua, H., Ahring, R.M., Powell, J. and Rommann, L.M. (1976). Increasing seed germination of rangeland species. Oklahoma Agricultural Experiment Station, Research Report No. P.735, pp. 27-30.

12. Felippe, G.M., Silva, J.C.S. and Cardoso, V.J.M. (1983). Germination studies in Andropogon gayanus Kunth. Revista Brasileira de Botanica, 6, 41-48.

13. Goedert, C. (1984). Seed dormancy of tropical forage grasses and implications for the conservation of genetic resources. Ph.D. Thesis, University of Reading.

14. Prentice, L.J. (1981). Observations on the germination time on rangegrasses. Newsletter of the Association of Official Seed Analysts, 55, 59.

ARISTIDA

A. armata

A. contorta F. Muell.

A. longespica Poir.

A. longiseta

A. murina Cay.

A. purpurea

A. ramosa R. Br.

I. Evidence of dormancy

Seed lots of A. armata, A. ramosa, A. contorta and A. longespica have shown considerable dormancy requiring after-ripening periods of between 4 and 18 months for dormancy to be removed (1,2,6-8).

II. Germination regimes for non-dormant seeds

-

III. Unsuccessful dormancy-breaking treatments

A. contorta

Pre-chill: 5°C, 8w (7)

A. longespica

Constant temperatures: 10°C, 20°C, 30°C in light, 12h/d, or dark (1)

Potassium nitrate: co-applied, 200 ppm (1)

GA₃: co-applied, 200 ppm (1)

Thiourea: co-applied, 200 ppm (1)

A. longiseta

Constant temperatures: 20°C, 25°C, 35°C (3,5)

Pre-chill: 0°C (3)

A. murina

Light: fluorescent, 2.2 W m^-2, 12h/d, at 20°C, (4); red, 0.37 W m^-2, 5,25 min, at 20°C (4)

IV. Partly-successful dormancy-breaking treatments

A. armata

Alternating temperatures: 25°/30°C (12h/12h) in light (2)

Pre-chill: 4°C, 6w (2)

Pre-dry: 70°C (2)

A. contorta

Constant temperatures: 30°C in light (8)

Alternating temperatures: 25°/30°C (12h/12h) (7)

Scarification: sand paper (7)

Pre-soak: 48h (7)

GA₃: co-applied, 10^-5g/ml, with or without seed covering structures (8)

Thiourea: co-applied, 10^-2 M, with or without seed covering structures (8)

Removal of seed covering structures: seed coat (8)

Hydrogen peroxide: pre-applied, 48h, 1 M (8)

Potassium cyanide: pre-applied, 24h, 10^-2 M (8)

Sodium azide: pre-applied, 24h, 10^-3 M (8)

A. ramosa

Constant temperatures: 20°-30°C (6)

Light: (6)

Removal of seed covering structures: seed coat (6)

V. Successful dormancy-breaking treatments

A. armata

Alternating temperatures: 25°/30°C (12h/12h), in light, dehulled seed (2)

A. contorta

Alternating temperatures: 25°/30°C (night/day), dehulled seed (7)

A. longespica

Pre-chill: 5°C, 12-24w, germinate at 30°C in light, 12h/d (1)

Removal of seed covering structures: excise embryo, germinate at 30°C in light, 12h/d (1)

A. longiseta

Alternating temperatures: 20°-24°/41°C (night/day) (3)

VI. Comment

Successful germination test regimes for accessions of Aristida spp. are likely to include alternating temperatures, seed coat removal, and probably light (low intensity). The amplitude of temperature alternation required to promote full germination does not appear to be particularly great - 5°C (2,7) - although greater amplitudes may also be satisfactory - 17°C (3). For the present it is suggested that the regime 25°/30°C (12h/12h) be used after the seed coats have first been removed.

VII. References

1. Baskin, J.M. and Caudle, C. (1967). Germination and dormancy in cedar glade plants. I. Aristida longespica and Sporobolus vaginiflorus. Journal of the Tennessee Academy of Science, 42, 132-133.

2. Brown, R.F. (1982). Seed dormancy in Aristida armata. Australian Journal of Botany, 30, 67-73.

3. Evans, G.R. and Tisdale, E.W. (1972). Ecological characteristics of Aristida longiseta and Agropyron spicatum in West-Central Idah o. Ecology, 53, 137-142.

4. Ginzo, H.D. (1978). Red and far red inhibition of germination in Aristida murina Cav. Zeitschrift fur Pflanzenphysiologie, 90, 303-307.

5. Jackson, C.V. (1928). Seed germination in certain New Mexico range grasses. Botanical Gazette, 86, 270-294.

6. Lodge, G.M. and Whalley, R.D.B. (1982). Establishment of warm- and cool-season native perennial grasses on the north-west slopes of New South Wales. I. Dormancy and germination. Australian Journal of Botany, 29, 111-119.

7. Mott, J.J. (1972). Germination studies on some annual species from an arid region of Western Australia. Journal of Ecology, 60, 293-304.

8. Mott, J.J. (1974). Mechanisms controlling dormancy in the arid zone grass Aristida contorta. I. Physiology and mechanisms of dormancy. Australian Journal of Botany, 22, 635-645.

AVENA

A. barbata Brot.	slender wild oat
A. byzantina K. Koch	red oat
A. fatua L.	spring or common wild oat
A. ludoviciana Durieu	winter wild oat
A. nuda L.	naked oat
A. sativa L.	common oat
A. sativa L. x A. fatua L.	dormoat
A. sterilis L.	animated oat
A. strigosa Schreber	bristle or small oat

I. Evidence of dormancy

Dormancy is common in the cultivated oat A. sativa (2,10,16,50,53), and pronounced in the wild oat species A. barbata (35,37), A. byzantina (13,48), A. fatua (1,5,6,9,21,30,31,42,51,52), A. ludoviciana (44,45,54), A. nuda (10), A. sterilis (13), and the hybrid dormoat A. sativa x A. fatua (3,18).

II. Germination regimes for non-dormant seeds

A. byzantina, A. sativa

BP; S: 20°C; 15°C: 10d (AOSA)

BP; S: 20°C: 10d (ISTA)

III. Unsuccessful dormancy-breaking treatments

A. byzantina

Pre-soak: 20h (48)

A. fatua

Constant temperatures: 5°-30°C (8); 5°-15°C (17); above 25°C (17,39,41,43,49)

Alternating temperatures: 10°-40°/40°-10°C (39)

Light: (5,23,28,31,39); 6x10³ erg cm^-2 s^-1 (21); white, blue, infra-red, red (14)

Oxygen: below 20% (5,21)

Carbon dioxide: 0-20% (21)

Pre-soak: 10°C, 48h (22); 25°C, 16-112h (23); 15 min-8h (26)

Aluminium phosphide: 48,72h fumigation (11)

Sodium azide: co-applied, 2x10^-3 M (15); co-applied, 1-2x10^-4 M (52); co-applied, 2, 4x10^-3 M (52); co-applied, 10^-3 M, plus 2-chloroethyl trimethylammonium chloride, co-applied, 5x10^-2 M (52); co-applied, 10^-3 M, plus salicylhydroxamic acid, co-applied, 3x10^-3 M (52)

GA₃: co-applied, 1, 1000 ppm, in light (28); co-applied, 10^-8-10^-5 M, intact or dehulled seeds (26)

Thiourea: co-applied, 10^-2-10^-4 M (25)

Kinetin: co-applied, 10^-4-10^-5 M (25)

Ethrel: co-applied, 10-500 ppm (25)

Naphthylacetic acid: co-applied, 10^-6 M (25)

Abscisic acid: co-applied, 10^-3, 10^-4 M (25)

Ethylene chlorohydrin: pre-applied, 1 min, 1, 3, 6% (31)

Dichloroethylene: pre-applied, 1 min, 0.1-1% (31)

Sodium thiocyanate: pre-applied, 1h, 2, 3% (31)

Potassium nitrite; co-applied, 1 M (39)

Methylene blue:pre-applied, 24h, 10^-3 M (47)

Reduced nitrogenous compounds: pre-applied, 24h (47)

Sodium fluoride: pre-applied, 24h, 10^-2, 10^-3 M (47)

2-4 Dinitrophenol: pre-applied, 24h, 10^-3-10^-6 M (47)

Sodium arsenate: pre-applied, 24h, 10^-2, 10^-3 M (47)

Sodium hypochlorite: pre-applied, 1 min-6h, 6% (26); pre-applied, 0.25-2h, 8x10^-1 M (29); co-applied, dehulled seed, 1.3-135x10^-3 M (29)

Sucrose: (22)

Hydrogen peroxide: co-applied, 0.375-3x10^-1 M (29); co-applied, 1.5x10^-1 M, dehulled seeds (29)

Removal of seed covering structures: (26,29,31); pierce, germinate in excess water (29)

Pre-dry: (25)

A. ludoviciana

Light: (54)

A. sativa

Vacuum: partial, 10,30 min (16)

Carbon dioxide: 30-38.7%, plus 12.8-14.7% oxygen (16)

Pre-soak: 1-5h (20); 12,24h (23,34)

Potassium cyanide: pre-applied, 24h, 10^-4 M (36)

Sodium azide: pre-applied, 24h, 10^-2 M (36)

Sodium sulphide: pre-applied, 24h, 10^-3, 10^-4 M (36)

Hydroxylamine: pre-applied, 24h, 10^-1, 10^-3, 10^-4 M (36)

Dimercaptol: pre-applied, 24h, 10^-3, 10^-4 M (36)

Diethyldithiocarbamate: pre-applied, 24h, 10^-3M (36)

Iodoacetate: pre-applied, 24h, 10^-3, 10^-4 M (36)

Sodium monofluoroacetate: pre-applied, 24h, 10^-3 M (36)

2,4 Dinitrophenol: pre-applied, 24h, 10^-2-10^-6 M (36)

A. sativa x A. fatua

Removal of seed covering structures: (3)

Warm stratification: 20°C, 1-4d, germinate at 3°C, 7°C (3)

GA₃: co-applied, 0.1, 1 ppm, dehulled seeds (3)

IV. Partly-successful dormancy-breaking treatments

A. barbata

Removal of seed covering structures: pricking (37)

A. byzantina

Pre-chill: 7°C, 5d (48)

Pre-dry: (48)

Scarification: sulphuric acid, 10%, 5 min, then pre-dry, 2h, then

GA₃, pre-applied, 20h, 100, 250, 500 ppm (48); sulphuric acid, 10%, 5 min, then pre-dry, 2h, then potassium nitrate, pre-applied, 20h, 0.1, 0.2, 0.5% (48)

A. fatua

Constant temperatures: 10°C (39,54); 10°-25°C (17,43); 15°C (1,44); 3°C, 10°C (40); 8°-16°C (42)

Alternating temperatures: 11°/14°-23°C (12h/12h) (43); 17°/20°-30°C (12h/12h) (43)

Light: dark (14,21,23,28,31,39)

Removal of seed covering structures: (5,6,9,21); cut, pierce or prick (6,27,28,29,37,54,58)

Ethrel: co-applied, 100-5000 ppm (1)

Potassium nitrate: pre-applied, 24, 48h, 0.2-2% (31); pre-applied, 1-6h, 1% (31); co-applied, 10^-2M (39,40); co-applied, 0.2% (23); co-applied, 0.2%, plus pre-chill, 5°-7°C, 10-14d (6)

Potassium nitrite: co-applied, 10^-4 -10^-1 M (39)

Potassium cyanide: pre-applied, 24h, 10^-2 -10^-4 M (47)

Sodium nitrate: co-applied, 0.2% (23)

Sodium nitrite: pre-applied, 24h, 10^-2 M (47)

Sodium azide: pre-applied, 3,6h, 0.5-2x10^-3, M (15); pre-applied, 24h, 10^-3, 10^-4 M (47); co-applied, 0.5x10^-3, 10^-3 M (15); co-applied, 0.2-2x10^-3 M (52)

Sodium hypochlorite: pre-applied, 1.5h, 0.8 M (29); pre-applied, 0.5-2h, 0.8 M, then GA₃, co-applied, 10^-8 -10^-3 M (26); pre-applied, 15,30 min, 0.8 M, dehulled seeds or naked caryopses (29); pre-applied, 1-30s, 0.8 M, dehulled seeds, then GA₃, co-applied, 5x10^-4 M (29); pre-applied, 3h, 0.8 M, dehulled seeds (29); pre-applied, 6h, 0.54-0.8 M, dehulled seeds (29); pre-applied, 1h, 0.8 M, then hydrogen peroxide, co-applied, 0.15 M (29); co-applied, 5.4x10^-3 M - 0.1 M, dehulled seeds (29)

Sodium thiocyanate: pre-applied, 1h, 1% (31)

GA₃: pre-applied, 30 min, 1,10,100 ppm (6); pre-applied, 24h, 400 ppm (55); co-applied, 10 ppm (6); co-applied, 25,50 ppm (19); co-applied, 10^-2 M (25,39); co-applied, 50-500 ppm, light (28); co-applied, 1-500 ppm, dark (28); co-applied, 10^-4 -10^-3 M, intact or dehulled seeds (26,29); co-applied, 500, 1000, 2500 ppm (46); co-applied, 1500 ppm (51); co-applied, 1.44x10^-3 M (58)

Hydrogen peroxide: co-applied, 0.1 M (22); co-applied, 0.15 M, intact, pierced, or dehulled seeds (29); co-applied, 37.5x10^-3 -1.5x10^-1 M, dehulled seeds (29); co-applied, 10^-2 M, dehulled seeds (23)

Oxygen: above 20% (5); 20-80% (6,21); 60, 100% (31)

Pre-chill: 0°C, 90d (31)

Pre-soak: 48h (22,31)

Ether: (31)

Aluminium phosphide: 6-18h fumigation (11)

Removal of seed covering structures: pierce, plus GA₃, co-applied, 10^-8 -10^-3 M (27); dehull, pierce, plus GA₃, co-applied, 10^-8 M (26); dehull, scarify (6,31)

A. ludoviciana

Removal of seed covering structures: (54)

A. sativa

Pre-chill: 5°C, 3d (2)

Potassium cyanide: pre-applied, 24h, 10^-2, 10^-3 M (36)

Sodium azide: pre-applied, 24h, 10^-3, 10^-4 M (36)

Hydrogen sulphide: pre-applied, 24h, 10^-1, 10^-2 M (36)

Hydroxylamine: pre-applied, 24h, 10^-2, M (36)

Diethyldithiocarbamate: pre-applied, 24h, 10^-4, M (36)

Malonate: pre-applied, 24h, 10^-1, 10^-2 M (36)

Sodium monofluoroacetate: pre-applied, 24h, 10^-2 M (36)

Sodium sulphide: pre-applied, 24h, 10^-1, 10^-2 M (36)

GA₃: co-applied, 20 ppm (32,33); co-applied, 400-800 ppm (34); pre-applied, 15-18h, 150 ppm (2)

Pre-dry: 2d (2); 50°C, 2d plus 70°C, 5h (2); 40°C, 12h (16); 40°C, 5d (20); 50°C, 2d, then pre-chill, 5°C, 3d (2)

Removal of seed covering structures: (16,32,50)

Vacuum: partial, 1h (16)

A. sativa x A. fatua

Pre-chill: 3°-7°C, 1-4d (3)

GA₃: co-applied, 10, 100 ppm, dehulled seeds (3); co-applied, 0.1-10 ppm, peeled caryopses (3)

A. sterilis

Removal of seed covering structures: dehull (59)

V. Successful dormancy-breaking treatments

A. barbata

Constant temperatures: 10°C (56)

Alternating temperatures: 5°/20°C, 5°/15°C (16h/8h) (56)

A. byzantina

Pre-dry, Pre-chill, GA₃ (ISTA)

Pre-chill, Pre-dry (AOSA)

A. fatua

Constant temperatures: 4°C (41,49)

Warm stratification: 20°C, 21d, plus GA₃, co-applied, 1.4x10^-4 M (52)

GA₃: co-applied, 1000 ppm (6,28); co-applied, 100 ppm (19); co-applied, 100 ppm, dehulled seeds (23)

Sodium azide: pre-applied, 6h, 10^-3 M (15); pre-applied, 21d, dark, 0.8x10^-3, 10^-3 M, then GA₃, co-applied, 1.4x10^-4 M (52); co-applied, 0.8x10^-3, 10^-3 M, plus GA₃, 1.4x10^-4, 2.8x10^-4 M (52)

Potassium nitrate: pre-applied, 12,24h, 1% (31); pre-applied, 1-24h, 2% (31); co-applied, 2x10^-4 -2x10^-2 M, in light (57)

Removal of seed covering structures: (22,28); plus oxygen, 100% (9); dehull and prick (5,14,23,29); dehull, prick and re-prick (39); dehull, prick, plus GA₃, co-applied, 10 ppm (42); dehull, prick, plus GA₃, co-applied, 10^-7 -10^-3 M (27); prick, plus GA₃, co-applied, 1.44x10^-3 M, at 15°C in light, 10.7x10^-6 mol m^-2 s^-1, 8h/d (58); dehull, prick, plus hydrogen peroxide, co-applied, 0.15 M (26); dehull, plus sodium hypochlorite, pre-applied, 1h, 0.8 M (26,29); dehull, plus sodium hypochlorite, pre-applied, 1h, 0.8 M, then GA₃, co-applied, 10^-8 -10^-3 M (26,29); dehull, plus sodium hypochlorite, pre-applied, 1h, 0.8 M, then hydrogen peroxide, co-applied, 0.15 M (29); dehull, plus sodium hypochlorite, pre-applied, 1h, 0.8 M, then GA₃, co-applied, 5x10^-4 M (29)

Sodium hypochlorite: pre-applied, 2h, 0.8 M, then GA₃, co-applied, 10^-4 M (26); pre-applied, 2h, 0.8 M, then dehull (29)

Hydrogen peroxide: co-applied, 0.3 M, dehulled seeds (29); co-applied, 0.15 M, dehulled seeds in excess moisture (29)

Aluminium phosphide: 18-24h fumigation (11)

A. sativa

Pre-dry, Pre-chill, GA₃ (ISTA)

Pre-chill, Pre-dry (AOSA)

Constant temperatures: 12°-15°C (2); 7°-17°C (4); 4°-24°C (41); 5°-12°C (20); 6°-14°C (38); 4°-12°C (50); 2°C, 10°C (10); 7.5°C (12); 12°C, 7d, then 20°C, 3d (33,34); 15°C (13,24)

Pre-chill: 4°C, 4d (50); 10°C, 5d (16); 5°C, 6d (53); 5°C, 7d (32)

GA₃: co-applied, 200 ppm (32,33); co-applied, 400 ppm (32,34); co-applied, 500 ppm (7)

Potassium nitrate: co-applied, 0.2% (24,50); pre-applied 1h, 2% (50); co-applied, 0.2%, plus pre-chill, 10°C, 5d (32); co-applied, 0.2%, dehull (24)

Calcium nitrate: co-applied, 0.2% (50); pre-applied, 1h, 2% (50)

Ammonium nitrate: co-applied, 0.2% (50); pre-applied, 1h, 2% (50)

Removal of seed covering structures: (53); dehull, pre-chill, 10°C, 5d (16); dehull, prick (16,20)

Oxygen: 51, 59, 100% (16)

A. sativa x A. fatua

Constant temperatures: 7°C (3)

GA₃: co-applied, 100 ppm, naked caryopses (3)

Removal of seed covering structures: excise embryo (3)

VI. Comment

A low constant temperature is an essential component of suitable germination test regimes for accessions of Avena spp. The range 7° to 10°C is suggested as being the most suitable.

A. byzantina The ISTA and AOSA recommendations for breaking dormancy (pre-chill, pre-dry, potassium nitrate) are not completely effective in promoting the germination of dormant seeds of A. byzantina (48).

A. fatua Procedures which combine the action of several dormancy-breaking agents are more likely to be successful (e.g. 29). The following procedure has been found to be satisfactory. Test at 7.5° to 10°C for 28 days with removal of the seed covering structures once the seed has imbibed, pricking in the area of the embryo, and subsequent repricking of ungerminated seeds after 28 days and continue test for a further period (39,A). An alternative procedure (which is equally effective but delays the time at which the onerous task of removing seed coats and pricking is performed and reduces the number of seeds pricked) is to test intact seeds at 7.5° to 10°C for 21 days, then remove seed covering structures and prick ungerminated seeds in the area of the embryo and test for a further 21 days at 7.5° to 10°C (A). Another alternative is to prick the seeds and test in light with gibberellic acid co-applied at 1.44x10^-3 M (58). Note that light tends to promote the germination of partly-dormant seed lots but is ineffective with strongly dormant seed lots (58) - unless combined with several other dormancy-breaking agents.

A. sativa Testing at low temperatures is the most satisfactory method of promoting germination in the cultivated oat (2,4,10,12,13,16,20,24,32,34,37,38,42). Testing at between 7.5° and 10°C for 28 days is recommended (A). Not only does this promote full germination of the dormant seeds but it is also safe for non-dormant and aged seeds (A).

VII. References

1. Adkins, S.W. and Ross, J.D. (1981). Studies in wild oat seed dormancy. I. The role of ethylene in dormancy breakage and germination of wild oat seeds (Avena fatua L.). Plant Physiology, 67, 358-362.

2. Andersen, S. (1965). The germination of freshly harvested seed of ripe and unripe barley and oats. Euphytica, 14, 91-96.

3. Andrews, C.J. and Burrows, V.D. (1972). Germination response of dormoat seeds to low temperature and gibberellin. Canadian Journal of Plant Science, 52, 295-303.

4. Atterberg, A. (1907). Die Nachreife des Getreides. Landwirtsch Versuch Stat, 67, 129-143.

5. Atwood, W.M. (1914). A physiological study of the germination of Avena fatua. Botanical Gazette, 57, 386-414.

6. Baker, L.O. and Leighty, D.H. (1958). Germination studies with wild oat seeds. Proceedings 16th West Weed Control Conference, 69-74.

7. Bekendam, J. (1975). Report of the working group on the application of gibberellic acid in routine germination testing to break dormancy of cereal seed. Seed Science and Technology, 3, 92-93.

8. Bewley, J.D. and Black, M. (1982). Physiology and biochemistry of seeds in relation to germination. Volume 2. Viability, dormancy and environmental control. Springer-Verlag, Berlin.

9. Black, M. (1959). Dormancy studies in seed of Avena fatua. I. The possible role of germination inhibitors. Canadian Journal of Botany, 37, 393-402.

10. Brown, E., Stanton, T.R., Wiebe, G.A. and Martin, J.H. (1948). Dormancy and the effect of storage on oats, barley, and sorghum. USDA Technical Bulletin, No. 953.

11. Cairns, A.L.P. and Villiers, O.T. de (1980). Effect of aluminium phosphide fumigation on the dormancy and viability of Avena fatua seed. South African Journal of Science, 76, 323.

12. Chippindale, H.G. (1934). The effect of soaking in water on the "seeds" of some gramineae. Annals of Applied Biology, 21, 225-232

13. Coffman, F.A. and Stanton, T.R. (1938). Variability in germination of freshly harvested Avena. Journal of Agricultural Research, 57-72.

14. Cumming, B.G. and Hay, J.R. (1958). Light and dormancy in wild oats (Avena fatua L.). Nature, 182, 609-610.

15. Fay, P.K. and Gorecki, R.S. (1978). Stimulating germination of dormant wild oat (Avena fatua) seed with sodium azide. Weed Science, 26, 323-326.

16. Forward, B.F. (1958). Studies of germination in oats. Proceedings of the International Seed Testing Association, 23, 5-37.

17. Friesen, G. and Shebeski, L.H. (1961). The influence of temperature on the germination of wild oat seeds. Weeds, 9, 634-638.

18. Garber, R.J. and Quisenberry, K.S. (1923). Delayed germination and the origin of false wild oats. The Journal of Heredity, 14, 267-274.

19. Green, J.G. and Helgeson, E.A. (1957). The effect of gibberellic acid on dormant seeds of wild oats. Proceedings 14th North Central Weed Control Conference, USA, 39.

20. Harrington, G.T. (1923). Forcing the germination of freshly harvested wheat and other cereals. Journal of Agricultural Research, 23, 79-100.

21. Hart, J.W. and Berrie, A.M.M. (1966). The germination of Avena fatua under different gaseous environments. Physiologia Plantarum, 19, 1020-1025.

22. Hay, J.R. (1962). Experiments on the mechanism of induced dormancy in wild oats, Avena fatua L. Canadian Journal of Botany, 40, 191-202.

23. Hay, J.R. and Cumming, B.G. (1959). A method for inducing dormancy in wild oats (Avena fatua L.). Weeds, 7, 34-40.

24. Heit, C.E. (1948). Thirty-eighth annual meeting. Report of subcommittee on dormancy of seeds. Proceedings of the Association of Official Seed Analysts, 38, 25-26.

25. Holm, R.E. and Miller, M.R. (1972). Weed seed germination responses to chemical and physical treatments. Weed Science, 20, 150-15

26. Hsiao, A.I. (1979). The effect of sodium hypochlorite and gibberellic acid on seed dormancy and germination of wild oats (Avena fatua). Canadian Journal of Botany, 57, 1729-1734.

27. Hsiao, A.I., McIntyre, G.I. and Hanes, J.A. (1983). Seed dormancy in Avena fatua. 1. Induction of germination by mechanical injury. Botanical Gazette, 144, 217-222.

28. Hsiao, A.I. and Simpson, G.M. (1971). Dormancy studies in seed of Avena fatua. 7. The effects of light and variation in water regime on germination. Canadian Journal of Botany, 49, 1347-1357.

29. Hsiao, A.I. and Quick, W.A. (1984). Actions of sodium hypochlorite and hydrogen peroxide on seed dormancy and germination of wild oats (Avena fatua). Weed Research, 24, 411-419.

30. Jana, S., Acharya, S.N. and Naylor, J.M. (1979). Dormancy studies in seed of Avena fatua. 10. On the inheritance of germination behaviour. Canadian Journal of Botany, 57, 1663-1667.

31. Johnson, L.P.V. (1935). General preliminary studies on the physiology of delayed germination in Avena fatua. Canadian Journal of Research, Section C, 13, 283-300.

32. Kahre, L. (1969). Comparisons of methods for germination. Report from the working group on cereal seed. Proceedings of the International Seed Testing Association, 34, 585-598.

33. Kahre, L., Kolk, N. and Fridz, T. (1965). Gibberellic acid for breaking of dormancy in cereal seed. Proceedings of the International Seed Testing Association, 30, 887-891.

34. Kahre, L., Kolk, H. and Wiberg, H. (1962). Note on dormancy-breaking in seeds. (Cereals and Timothy). Proceedings of the International Seed Testing Association, 27, 679-683.

35. Laude, H.M. (1956). Germination of freshly harvested seed of some western range species. Journal of Range Management, 9, 126-129.

36. Major, W. and Roberts, E.H. (1968). Dormancy in cereal seeds. I. The effects of oxygen and respiratory inhibitors. Journal of Experimental Botany, 58, 77-89.

37. Marshall, D.R. and Jain, S.K. (1970). Seed predation and dormancy in the population dynamics of Avena fatua and A. barbata. Ecology, 51, 886-891.

38. Munerati, M.O. (1926). Possibilité de déterminer l'âge des graines de blé par la temperature de leur germination. Comptes Rendus de l'Académie des Sciences, Paris, 182, 535-537.

39. Murdoch, A.J. (1982). Factors influencing the depletion of annual weed seeds in the soil. Ph.D. Thesis, University of Reading, UK.

40. Murdoch, A.J. and Roberts, E.H. (1982). Biological and financial criteria of long-term control strategies for annual weeds. Proceedings 1982 British Crop Protection Conference Weeds. 741-748.

41. Naylor, J.M. and Fedec, P. (1978). Dormancy studies in seed of Avena fatua. 8. Genetic diversity affecting reponse to temperature. Canadian Journal of Botany, 56, 2224-2229.

42. Naylor, J.M. and Jana, S. (1976). Genetic adaptation for seed dormancy in Avena fatua. Canadian Journal of Botany, 54, 306-312.

43. Paterson, J.G., Boyd, W.J.R. and Goodchild, N.A. (1976). Effect of temperature and depth of burial on the persistence of seed of Avena fatua L. in western Australia. Journal of Applied Ecology, 13, 841-847.

44. Quail, P.H. and Carter, O.G. (1968). Survival and seasonal germination of seeds of Avena fatua and A. ludoviciana. Australian Journal of Agricultural Research, 19, 721-729.

45. Quail, P.H. and Carter, O.G. (1969). Dormancy in seeds of Avena ludoviciana and A. fatua. Australian Journal of Agricultural Research, 20, 1-11.

46. Richardson, S.G. (1979). Factors influencing the development of primary dormancy in wild oat seeds. Canadian Journal of Plant Science, 59, 777-784.

47. Roberts, E.H. and Madden, D. Cited by Roberts, E.H. (1972). Oxidative processes and the control of seed germination. In Seed Ecology (ed. W. Heydecker), pp. 189-218, Butterworths, London.

48. Santacruz, R.F. (1981). [Response of oats to seed dormancy breaking treatment.] ICA. Information Colombia, 15, 6-9. (From Seed Abstracts, 1983, 6, 2205.)

49. Sawhney, R. and Naylor. J.M. (1980). Dormancy studies in seed of Avena fatua. 12. Influence of temperature on germination behavior of non-dormant families. Canadian Journal of Botany, 58, 578-581.

50. Schwendiman, A. and Shands, H.L. (1943). Delayed germination on seed dormancy in vicland oats. Journal of American Society of Agronomy, 35, 681-688.

51. Somody, C.N., Nalewaja, J.D. and Miller, S.D. (1981). Morphology characteristics and dormancy of 1200 wild oat selections. Proceedings of North Central Weed Control Conference, 36, 34.

52. Upadhyaya, M.K., Naylor, J.M. and Simpson, G.M. (1982). The physiological basis of seed dormancy in Avena fatua L. I. Action of the respiratory inhibitors sodium azide and salicylhydroxamic acid. Physiologia Plantarum, 54, 419-424.

53. Whitcomb, W.O. (1923). Germination of newly threshed grains. Proceedings of the Association of Official Seed Analysts, 14, 84-88.

54. Whittington, W.J., Hillman, J., Gatenby, S.M., Hooper, B.E. and White, J.C. (1970). Light and temperature effects of the germination of wild oats. Heredity, 25, 641-650.

55. Wiberg, H. and Kolk, H. (1960). Effect of gibberellin on germination of seeds. Proceedings of the International Seed Testing Association, 25, 440-445.

56. Young, J.A., Evans, R.A. and Kay, B.L. (1973). Temperature requirements for seed germination in an annual-type rangeland community. Agronomy Journal, 65, 656-659.

57. Hilton, J.R. (1984). The influence of light and potassium nitrate on the dormancy and germination of Avena fatua L. (wild oat) seed and its ecological significance. New Phytologist, 96, 31-34.

58. Hilton, J.R. and Bitterli, C.J. (1983). The influence of light on the germination of Avena fatua L. (wild oat) seed and its ecological significance. New Phytologist, 95, 325-333.

59. Tal, M. (1977). Abscisic acid and germination in Avena sterilis L. Israel Journal of Botany, 26, 100-103.

BOTHRIOCHLOA

B. intermedia (R. Br.) A. Camus
B. ischaemum (L.) Keng	yellow bluestem
B. macra (Steud.) Blake	red grass

I. Evidence of dormancy

Dormancy is often present in seeds of Bothriochloa spp. (2-4). After-ripening for 8 months or so is reported to result in loss in dormancy (4).

II. Germination regimes for non-dormant seeds

B. ischaemum

TP; S: 20°/30°C (16h/8h): 21d (AOSA)

B. macra

Constant temperatures: 25°C (4)

Alternating temperatures: 15°/25°C, 20°/30°C (16h/8h) in light (3); 20°/30°C (16h/8h) in light (2)

III. Unsuccessful dormancy-breaking treatments

-

IV. Partly-successful dormancy-breaking treatments

B. intermedia

Removal of seed covering structures: (1)

B. ischaemum

Alternating temperatures: 20°/30°C (16h/8h) in light (2)

Pre-chill: 5°-10°C, 5d (2); 5°-10°C, 5d, plus potassium nitrate, co-applied, 0.2% (2)

Potassium nitrate: co-applied, 0.2% (2)

Removal of seed covering structures: (1)

B. macra

Removal of seed covering structures: (3,4)

GA₃: co-applied, 100 ppm (3)

Light: 6.5-7.5 W m^-2 (3)

V. Successful dormancy-breaking treatments

B. ischaemum

Light, Potassium nitrate, Pre-chill (AOSA)

B. macra

Removal of seed covering structures: lemma and palea, germinate at 20°/30°C (16h/8h) in light, plus GA₃, co-applied, 100 ppm (3); lemma and palea, germinate at 30°C (5)

VI. Comment

The literature cited (1-5) suggests light (8h/d), alternating temperatures and the removal of the lemma and palea to be the most stimulatory factors in promoting the germination of dormant seeds of Bothriochloa spp. It is suggested that the AOSA germination test procedure be followed but with the additional treatment of lemma and palea removal. AOSA recommend that seeds be pre-chilled at 5°C for 14 days. A 5-day pre-chill at 5°C is only partly-promotory (2), but treatment with gibberellic acid - co-applied, 100 ppm - can be effective when combined with seed coat removal (3). Consequently this treatment may be a worthwhile alternative to pre-chilling - particularly if a more rapid test procedure is required.

VII. References

1. Ahring, R.M., Eastin, J.D. and Garrison, C.S. (1975). Seed appendages and germination of two Asiatic bluestems. Agronomy Journal, 67,

2. Ahring, R.M. and Harlan, J.R. (1961). Germination characteristics of some accessions of Bothriochloa ischaemum (L.) Keng. Oklahoma Agricultural Experiment Station, Technical Bulletin T-89, 19pp.

3. Hagon, M.W. (1976). Germination and dormancy of Themeda australis, Danthonia spp., Stipa bigeniculata, and Bothriochloa macra. Australian Journal of Botany, 24, 319-327.

4. Lodge, G.M. and Whalley, R.D.B. (1981). Establishment of warm- and cool-season native perennial grasses on the North-west slopes of New South Wales. I. Dormancy and Germination. Australian Journal of Botany, 29, 111-119.

5. Watt, L.A. and Whalley, R.D.B. (1982). Establishment of small-seeded perennial grasses on black clay soils in North-western New South Wales. Australian Journal of Botany, 30, 611-623.

BOUTELOUA

B. chrondrosioides (HBK) Benth.
B. curtipendula (Michx.) Torr.	coronada side-oats grama
B. eriopoda Torr.	black grama
B. filiformis (Fowen) Griff.	slender grama
B. gracilis (HBK) Lag.	blue grama
B. parryi (Fowen) Griff.	parry grama
B. rothrockii Vasey	Roth rock grama

I. Evidence of dormancy

Dormancy may be exhibited by seeds of Bouteloua spp. (1,2,4,8-11) and may persist after 5 years dry storage at room temperature (3). Seeds of B. parryi and B. rothrockii are particularly dormant and very difficult to germinate (7).

II. Germination regimes for non-dormant seeds

B. curtipendula

TP: 15°/30°C (16h/8h): 28d (AOSA)

Alternating temperatures: 20°/30°C (16h/8h) in light (4)

B. filiformis

Constant temperatures: 20°C, 30°C, 35°C (7)

Alternating temperatures: 35°/10°C, 10°/35°C, 20°/40°C, 20°/35°C, 20°/30°C, 10°/30°C, 15°/25°C, 25°/40°C (18h/6h) (7); 25°/40°C, 20°/40°C (21h/3h) (7)

B. gracilis

TP: 20°/30°C (16h/8h): 28d (AOSA)

III. Unsuccessful dormancy-breaking treatments

B. curtipendula

Alternating temperatures: 10°-20°/20°-10°C (12h/12h) (8)

Potassium nitrate: co-applied, 0.2% (7)

B. eriopoda

Light: red, far red, 30 min (11); fluorescent, 8h/d (11)

Calcium nitrate: co-applied, 0.1, 0.2% (11)

Potassium nitrate: co-applied, 0.1-0.5% (11)

B. gracilis

Potassium nitrate: co-applied, 0.2% (7)

B. parryi, B. rothrockii

Constant temperatures: 20°-35°C (7)

Alternating temperatures: 20°/40°C, 25°/40°C, 35°/10°C, 10°/35°C, 20°/35°C, 20°/30°C in light (18h/6h) (7); 15°/25°C (18h/6h) (7)

Pre-chill: 3°-5°C, 7,14d (7)

Potassium nitrate: co-applied, 0.2%, alone or at the above alternating temperatures in the presence or absence of light (7)

Light: (7)

IV. Partly-successful dormancy-breaking treatments

B. chrondrosioides

Alternating temperatures: 20°/35°C, 25°/40°C (18h/6h) (7)

Potassium nitrate: co-applied, 0.2% (7)

B. curtipendula

Constant temperatures: 20°-35°C (7); 10°-40°C in light (8)

Alternating temperatures: 20°/30°C (16h/8h) in light (4,6,9); 10°/30°C, 15°/25°C, 20°/35°C, 25°/40°C, 20°/40°C, 35°/10°C (18h/6h) (7); 20°-40°/40°-20°C (12h/12h, 16h/8h, 20h/4h) (8)

Pre-chill: (3); 3°-5°C, 7, 14d (7); 3°-5°C, 7, 14d, plus potassium nitrate, co-applied, 0.2% (7)

Light: (3,5,6,7); 100 fc, 12h/d (8)

Sodium hypochlorite: pre-applied, 0.5h, 5.2% (3,4,5,6,9)

Removal of seed covering structures: (4); clip (9)

Alternating moisture: wet/dry/rewet (3)

Oxygen: 100% (3,9)

Pre-wash: (3); 0.5-3h (4)

Sodium carbonate: (3)

Hydrogen peroxide: (3)

B. eriopoda

Alternating temperatures: 20°-25°/35°C (18h/6h) (7); 20°/35°C, 15°/30°C, 20°/30°C (16h/8h) (11)

Potassium nitrate: co-applied, 0.2% (7)

GA₃: co-applied, 50 ppm (11)

Removal of seed covering structures: (11)

B. gracilis

Alternating temperatures: 20°/30°C, 15°/25°C (18h/6h) (7)

Potassium nitrate: co-applied, 0.2%, at 20°/30°C (16h/8h) in light (10)

V. Successful dormancy-breaking treatments

B. chrondrosioides

Potassium nitrate: co-applied, 0.2%, germinate at 20°/35°C or 25°/40°C (18h/6h) (7)

B. curtipendula

Light, Potassium nitrate (AOSA)

Alternating temperatures: 20°/30°C in light (18h/6h) (7); 10°/30°C, 15°/25°C, 10°/35°C (18h/6h) (7)

Removal of seed covering structures: lemma and palea (3,9)

Sodium hypochlorite: pre-applied, 0.5h, 5.2%, germinate in 100% oxygen atmosphere (9)

B. eriopoda

Potassium nitrate: co-applied, 0.2%, germinate at 20°-25°/35°C (18h/6h) (7)

B. gracilis

Light, Potassium nitrate (AOSA)

Alternating temperatures: 20°/30°C, 15°/25°C (18h/6h) (7)

VI. Comment

With the exception of those of B. parryi and B. rothrockii, the seed lots tested for germination in reference (7) were not particularly dormant. Consequently the dormancy-breaking treatments listed as successful by reference (7) may not promote full germination in more dormant accessions of B. chrondrosioides, B. curtipendula, B. eriopoda and B. gracilis. According to the AOSA dormant seed s of B. curtipendula require light or potassium nitrate for germination. In contrast to this recommendation light has been reported as inessential for germination (4-6,8,11) and potassium nitrate (co-applied, 0.2%) has been reported to reduce germination (7,11). Treatment with gibberellic acid, however, has been reported to be a very effective dormancy-breaking treatment (11).

Alternating temperature regimes are essential to promote the germination of dormant seeds of Bouteloua accessions (3,7,8,11). However, the AOSA prescription for B. curtipendula, 15°/30°C (16h/8h), appears to be less promotory than either 20°/30°C (16h/8h) or 15°/30°C (12h/12h) (8), whilst 35°/30°C (4h/20h) or 35°/15°C (8h/16h) are even more beneficial (8). Consequently it is suggested that the alternating temperature regime 20°/30°C (16h/8h) be adopted as a general germination test procedure for accessions of Bouteloua spp. with additional treatments of dehulling and GA₃ co-applied at 50 ppm where necessary, with a further suggestion that tests also be carried out at 35°/15°C (4-8h/20-16h) to determine whether this might provide a more suitable environment for germination.

References

1. Coukos, C.J. (1944). Seed dormancy and germination in some native grasses. Journal of American Society of Agronomy, 36, 337-345.

2. Jackson, C.V. (1928). Seed germination in certain New Mexico range grasses. Botanical Gazette, 86, 270-294.

3. Major, R.L. (1972). Seed dormancy of side-oats gramagrass Bouteloua curtipendula (Michx.). Dissertation Abstracts, 33B, 531

4. Sumner, D.C. and Cobb, R.D. (1962). Post harvest dormancy of coronado side-oats grama Bouteloua curtipendula (Michx.) Torr. as affected by storage temperature and germination inhibitors. Crop Science, 2, 321-325.

5. Sumner, D.C., Cobb, R.D. and Jones, L.G. (1959). Modification of standard germination procedure for coronado side-oats grama (Bouteloua curtipendula). Newsletter of the Association of Official Seed Analysts, 33, 7-9 and 27.

6. Sumner, D.C., Cobb, R.D. and Jones, L.G. (1960). The effect of temperature and light on the germination of coronado side-oats grama. Newsletter of the Association of Official Seed Analysts, 34, 12.

7. Toole, V.K. (1939). Germination requirements of the seed of some introduced and native range grasses. Proceedings of the Association of Official Seed Analysts, 30, 227-243.

8. Cole, D.F., Major, R.L. and Wright, L.N. (1974). Effects of light and temperature on germination of sideoats grama. Journal of Range Management, 27, 41-44.

9. Major, R.L. and Wright, L.N. (1974). Seed dormancy characteristics of sideoats gramagrass, Bouteloua curtipendula (Michx.) Torr. Crop Science, 14, 37-40.

10. Thornton, M.L. and Thornton, B.J. (1962). Firm seed and longevity of blue grama (Bouteloua gracilis). Proceedings of the Association of Official Seed Analysts, 52, 112-115.

11. Wright, L.N. and Baltensperger, A.A. (1964). Influence of temperature, light radiation, and chemical treatment on laboratory germination of black gramagrass, Bouteloua eriopoda Torr. Crop Science, 4, 168-171.

BRACHIARIA

B. brizantha (Hochst.) Stapf	palisade grass, signal grass
B. decumbens Stapf	signal grass, Surinam grass
B. dictyoneura (Fig. & De Not.) Stapf
B. dura Stapf
B. humidicola (Rendle) Schweickt	creeping signal grass, coronivia grass
B. miliiformis (Presl) Chase
B. mutica (Forsk.) Stapf [Panicum muticum Forsk.; P. purppurascens Raddi; P. barbinode Trin.]	para grass, Mauritius grass, malohillo, Angola grass, capim angola, egipto, penhalonga grass, mirable
B. plantaginea (Link) Hitchc. [Panicum plantagineum Link]	marmalade grass
B. radicans Napper [B. arrecta (Hack. ex Th. Dur. & Schinz) Stent.]	tanner grass
B. ramosa	brown top millet
B. ruziziensis Germain & Evrard	ruzi grass, Congo grass, Congo signal grass, kennedy ruzi

I. Evidence of dormancy

Dormancy in Brachiaria species can be particularly persistent and pronounced resulting in considerable problems for seed testing (7,10) and germplasm evaluation (1).

II. Germination regimes for non-dormant seeds

B. decumbens

TP: 20°/35°C (16h/8h): 21d (ISTA)

Alternating temperatures: 20°/35°C (16h/8h) in light, 21d (7)

B. humidicola, B. mutica

TP: 20°/35°C (16h/8h): 21d (ISTA)

B. ramosa

BP; TP: 20°/30°C (16h/8h); 30°C: 14d (AOSA)

III. Unsuccessful dormancy-breaking treatments

B. decumbens

Potassium nitrate: co-applied, 0.2% (11)

Pre-dry: 40°-80°C, 14h (11); 40°C, 12d (11)

Pre-soak: 70°C, 10 min (11)

Scarification: concentrated sulphuric acid, 5-20 min (11)

Light: (3)

B. dictyoneura

Pre-dry: (1)

Scarification: concentrated sulphuric acid, 15 min, plus thiourea, co-applied (1)

B. mutica

Pre-dry: 55°C, 4d (8)

Scarification: concentrated sulphuric acid, 15 min (8); sandpaper (8)

B. ruziziensis

Constant temperatures: 20°C, 25°C (9)

Light: (9)

Pre-dry: 50°C, 3d (8)

Removal of seed covering structures: excision of spikelet top (9)

IV. Partly-successful dormancy-breaking treatments

B. decumbens

Pre-chill: 5°C, 7d (11)

Potassium nitrate: co-applied, 0.2% (2,3)

Scarification: concentrated sulphuric acid (2); concentrated sulphuric acid, 5-20 min (11); concentrated sulphuric acid, 15 min (5,6); concentrated sulphuric acid, 13 min (3); concentrated sulphuric acid, 13 min, plus potassium nitrate, co-applied, 0.2%, germinate at 20°/35°C (16h/8h) in light (3); mechanical (11)

Pre-dry: 40°-80°C, 14h (11)

Pre-soak: 24h (11)

Hydrogen peroxide: pre-applied, 24,48h, 1 M (11)

Removal of seed covering structures: lemma and palea (5,11)

Light: 15000 lux (3)

B. dictyoneura

Removal of seed covering structures: lemma and palea (1)

Scarification: concentrated sulphuric acid, 20-25 min (1); concentrated sulphuric acid, 20-25 min, plus thiourea, co-applied (1)

B. humidicola

Potassium nitrate: co-applied, 0.2% (2)

Scarification: concentrated sulphuric acid, with or without potassium nitrate, co-applied, 0.2% (2)

B. ruziziensis

Alternating temperatures: 25°/15°C (12h/12h) (9)

Scarification: concentrated sulphuric acid, 15 min (4,8); mechanical (8)

V. Successful dormancy-breaking treatments

B. decumbens

Scarification, Light, Potassium nitrate (ISTA)

Potassium nitrate: co-applied, 0.2% (7)

Scarification: concentrated sulphuric acid, 13 min (7); concentrated sulphuric acid, 13 min, wash, then potassium nitrate, co-applied, 0.2% (10)

B. humidicola

Potassium nitrate (ISTA)

B. mutica

Scarification, Potassium nitrate (ISTA)

B. ramosa

Light, Potassium nitrate, Pre-dry, test at 30°C (AOSA)

B. ruziziensis

Scarification, Potassium nitrate (ISTA)

Removal of seed covering structures: dehull (9)

Hydrogen peroxide: pre-applied, 24h, 1 M (9)

Brachiaria spp.

Scarification: concentrated sulphuric acid, 13 min, wash, then potassium nitrate, co-applied, 0.2%, at 20°/35°C (16h/8h) in light (10)

VI. Comment

The apparently satisfactory procedure for Brachiaria (10) - described above - has been found elsewhere to fail to promote the germination of all viable seeds (3), at least over a 21 day germination test period. An alternating temperature regime of 15°/30°C or 10°/30°C (16h/8h) can be extremely promotory for B. humidicola but not promotory for B. decumbens (A). More recent work with B. humidicola has shown that alternating temperature regimes of 35°/13°C (4h/20h) or 35°/16°C (4h/20h) with the addition of potassium nitrate, co-applied, 10^-2 M, in the latter regime can be very successful dormancy-breaking treatments (12). Note the short period of exposure to the higher temperature during each daily cycle: this is the most effective thermoperiod for this species (12). It is suggested that either of these regimes be applied to B. humidicola, whilst no suggestion can be made at present for dormant accessions of B. decumbens.

VII. References

1. Anonymous (1981). Agronomy in the isohyperthermic savannas (carimagua). C.I.A.T. Tropical Pasture Program Report 1981, pp. 21-23.

2. Atalla, L.M.P. and Tosello, J. (1979). [Observations on dormancy in two species of Brachiaria: B. decumbens and B. humidicola under laboratory conditions.] Cientifica, 7, 353-355.

3. Beavis, C. (1984). Seed dormancy and germination of Brachiaria decumbens Stapf. (In press).

4. Davidson, D.E. (1966). Five pasture plants for Queensland. Queensland Agricultural Journal, 92, 460-466.

5. Filho, J.W. (1980). [Dormancy breaking studies on seeds of Brachiaria decumbens Stapf.] Boletim de Divulgacao, Escola Superior de Agricultura "Luiz de Queiroz", 24, 92-94.

6. Grof, B. (1968). Viability of seed of Brachiaria decumbens. Queensland Journal of Agricultural and Animal Science, 25, 149-152.

7. Johnston, M.E.H. (1981). Report of the germination committee working group on tropical and subtropical seeds 1977-1980. Seed Science and Technology, 9, 137-140.

8. MacLean, D. and Grof, B. (1968). Effect of seed treatments on Brachiaria mutica and B. ruziziensis. Queensland Journal of Agricultural and Animal Science, 25, 81-83.

9. Renard, C. and Capelle, P. (1976). Seed germination in ruzizi grass [Brachiaria ruziziensis (Germain & Evrard)]. Australian Journal of Botany, 24, 437-446.

10. Tonkin, J.H.B. (1981). Report of the germination committee working group on temperate grasses 1977-1980. Seed Science and Technology, 9, 147-156.

11. Whiteman, P.C. and Mendra, K. (1982). Effects of storage and seed treatments on germination of Brachiaria decumbens. Seed Science and Technology, 10, 233-242.

12. Goedert, C. (1984). Seed dormancy of tropical forage grasses and implications for the conservation of genetic resources. Ph.D. Thesis, University of Reading.

BROMUS

B. arvensis L.	field brome
B. brizaeformis Fisch. & Mey	quake grass
B. catharticus Vahl [B. willdenowii, B. unioloides HBK; B. Schraderi Kunth.]	rescue grass, Schraders brome
B. commutatus Schrad.	meadow brome
B. erectus Huds.	upright brome
B. inermis Leyss.	awnless brome, Hungarian brome, smooth brome
B. japonicus Thunb.
B. marginatus Steud.	mountain brome
B. mollis L.	soft chess
B. ramosus Huds.	hairy brome, wood brome
B. rigidus Roth	ripgut
B. secalinus L.	rye brome
B. sitchensis
B. sterilis L.	barren brome
B. tectorum L.	cheatgrass, downy chess, bronco grass, Mormon oats, junegrass

I. Evidence of dormancy

Seed lots of B. catharticus (7), B. marginatus (7), B. rigidus (6), B. secalinus (18) and B. sterilis (12) show onl y slight dormancy: after-ripening for 3 to 5 weeks is sufficient to remove this slight dormancy (12,18). Seed lots of B. inermis (1), B. mollis (6), B. ramosa (3) and B. tectorum (6) may be more dormant and may require after-ripening for between 4 (6) and 8 months (1) before dormancy is lost. Dormancy causes problems when testing seed lots of B. catharticus (5) and B. inermis (13,14) for germination.

II. Germination regimes for non-dormant seeds

B. arvensis

TP: 15°/25°C; 20°/30°C (16h/8h): 21d (ISTA)

TP: 15°/25°C; 20°/30°C (16h/8h): 14d (AOSA)

B. catharticus

TP; S; 20°/30°C (16h/8h): 28d (ISTA)

TP; S: 10°/30°C (16h/8h): 28d (AOSA)

B. inermis

TP: 15°/25°C; 20°/30°C (16h/8h): 14d (ISTA)

TP; BP: 20°/30°C (16h/8h): 14d (AOSA)

B. marginatus

TP: 15°/25°C; 20°/30°C (16h/8h): 14d (ISTA)

TP: 20°/30°C (16h/8h): 14d (AOSA)

B. mollis

TP: 20°/30°C (16h/8h): 14d (AOSA,ISTA)

B. sitchensis

TP: 20°/30°C; 15°/25°C (16h/8h): 21d (ISTA)

III. Unsuccessful dormancy-breaking treatments

B. brizaeformis

Light: at 10°C (16)

B. catharticus

Constant temperatures: 5°-35°C (5)

Potassium nitrate: co-applied, 0.2% (7)

Thiourea: co-applied, 0.2% (7)

B. commutatus

Light: at 10°C (16)

B. erectus

Light: red, 5 min, at 8.4°-11.8°C (12)

B. inermis

Constant temperatures: 22°-24°C (19)

Light: (7,13)

B. japonicus

Constant temperatures: 20°-30°C, in light or dark (16)

Light: at 10°C (16)

B. mollis

Light: red, 5 min, at 6.7°C, 8.4°C (12)

B. ramosus

Alternating temperatures: 20°/15°C (15h/9h), in light, 40 W m^-2, 15h/d (3)

B. rigidus

Light: at 10°C (16)

B. secalinus

Alternating temperatures: 20°/30°C (16h/8h) in light or dark (18)

Potassium nitrate: co-applied, 0.2% (18)

Light: 100-150 fc (18)

B. sterilis

Light: red, 5 min, at 10°-25.4°C (12); red, 1.4x10^-6 mol m^-2 s^-1, 8h/d, at 15°C (15); white, 10.7x10^-6 mol m^-2 s^-1, 8h/d, at 15°C (15)

B. tectorum

Alternating temperatures: 20°/30°C (16h/8h) in light or dark (18)

Potassium nitrate: co-applied, 0.2% (18)

Light: 100-200 fc, at 10°-30°C (16); 100-150 fc (18); dark, at 20°-30°C (16)

IV. Partly-successful dormancy-breaking treatments

B. brizaeformis

Constant temperatures: 15°C in light, 100-200 fc (16)

B. catharticus

Alternating temperatures: 10°/25°C (8h/16h), light, 8h/d (5); 5°-10°/15°-30°C (12h/12h) (5); 26°/5°C (24h/24h) (17)

Pre-chill: 3°-5°C, 7d (7)

Potassium nitrate: co-applied, 0.2% (5)

Light: (5,8)

Removal of seed covering structures: distal end cut (5)

GA₃: co-applied, 100 ppm (7)

B. commutatus

Constant temperatures: 15°C in light, 100-200 fc (16)

B. inermis

Alternating temperatures: 20°/30°C (16h/8h) in light, 8h/d (14)

Pre-chill: 3°-5°C, 7d (7)

Light: (8)

GA₃: co-applied, 100 ppm (7,8)

B. japonicus

Constant temperatures: 15°C, dark (16)

B. marginatus

Pre-chill: 3°-5°C, 7d (7)

Potassium nitrate: co-applied, 0.2% (7)

GA₃: co-applied, 100 ppm (7)

B. ramosus

Pre-chill: 5°C, 2m (3)

B. rigidus

Constant temperatures: 15°C (10); 15°C in light (16)

B. tectorum

Constant temperatures: 10°C, 15°C, dark (16)

Alternating temperatures: 7°/25°C, 7°/14°C (16h/8h) (16)

Potassium nitrate: co-applied, 10^-5, 10^-4, 10^-3 M (11); co-applied, 10^-4 M, plus GA₃, co-applied, 1.4x10^-4 M (11)

V. Successful dormancy-breaking treatments

B. arvensis

Pre-chill, Potassium nitrate (ISTA)

Light, Pre-chill (AOSA)

B. brizaeformis

Constant temperatures: 10°C, 15°C, dark (16)

B. catharticus

Pre-chill, Potassium nitrate (ISTA)

Light, Pre-wash, 48h, test in soil at 15°C (AOSA)

Alternating temperatures: 15°/30°C (16h/8h) (7)

Pre-soak: 2h, deglume, germinate at 15°-18°C, plus potassium nitrate, co-applied, 0.2% (4)

GA₃: co-applied, 100 ppm, germinate at 20°C in light (8)

Removal of seed covering structures: deglume, pierce (2,4,17); clip off distal end, germinate at 10°/25°C (8h/16h), in light, 8h/d, plus potassium nitrate, co-applied, 0.2% (5)

B. commutatus

Constant temperatures: 10°C, 15°C, dark (16)

B. erectus

Constant temperatures: 8.4°-27°C, dark (12)

Alternating temperatures: 8°/23°C, 10°/20°C, 15°/23°C (16h/8h), dark (12); 20°/15°C (15h/9h) in light, 40 W m^-2 (3)

Pre-chill: 2°C, 20d, germinate at 10°/20°C (16h/8h), dark (12)

B. inermis

Pre-chill, Potassium nitrate (ISTA)

Light, Pre-chill, test at 30°C for 9 additional days (AOSA)

Constant temperatures: 10°-30°C, dark (13)

Alternating temperatures: 15°/30°C (16h/8h) in dark (7); 20°/30°C (16h/8h) (19); 20°/30°C, 20°/35°C, 15°/25°C, 15°/30°C, 10°/20°C, 10°/30°C (15h/9h), dark (13)

Pre-chill: 10°C, 5d (13,14)

GA₃: co-applied, 100 ppm, at 20°C in light (8)

B. japonicus

Constant temperatures: 10°C, dark (16)

B. marginatus

Pre-chill, Potassium nitrate (ISTA)

Light (AOSA)

Alternating temperatures: 15°/30°C (16h/8h) (7)

GA₃: co-applied, 100 ppm, at 15°C in light (8)

B. mollis

Pre-chill (ISTA)

Light, Pre-chill (AOSA)

Constant temperatures: 15°C (10); 5°-28.8°C, dark (12)

Alternating temperatures: 5°/15°C, 15°/25°C, 10°/30°C, 15°/30°C, 15°/20°C, 20°/25°C, 25°/30°C (16h/8h) (10); 8°-23°C, 10°/20°C, 15°/23°C (16h/8h), dark (12)

B. rigidus

Constant temperatures: 10°C (10); 10°C, 15°C, dark (16)

Alternating temperatures: 5°/15°C, 2°/20°C (16h/8h) (10)

B. secalinus

Constant temperatures: 15°C, dark (18)

Pre-chill: 5°C, 7d, germinate at 20°/30°C (16h/8h) (18)

B. sitchensis

Pre-chill (ISTA)

B. sterilis

Constant temperatures: 15°C, dark (15)

Alternating temperatures: 8°/23°C, 10°/20°C, 15°/23°C (16h/8h), dark (12); 20°/15°C (15h/9h) in light, 40 W m^-2 (3)

Pre-chill: 2°C, 20d, germinate at 10°/20°C (16h/8h), dark (12)

B. tectorum

Constant temperatures: 15°C (20); 15°C, dark (18)

Alternating temperatures: 10°/30°C, 15°/30°C, 10°/25°C, 15°/25°C, 10°/20°C (16h/8h) (9); 14°/25°C (16h/8h), dark (16)

Pre-chill: 5°C, 7d, germinate at 20°/30°C (16h/8h) (18)

VI. Comment

The germination of dormant seed lots of most Bromus spp. is inhibited by light (12, 15, 16): with less dormant seed lots no inhibitory effects of light are observed (13, 18), but neither is germination promoted. Consequently despite AOSA prescriptions to the contrary it is suggested here that Bromus accessions be tested for germination in the dark. Slightly dormant or non-dormant seeds of Bromus spp. germin ate fully at constant temperatures between 10° and 15°C in the dark (10, 12, 13, 15, 16, 18, 20), but alternating temperatures are required for the more dormant lots (5, 7, 10, 12, 16). The AOSA/ISTA prescribed alternating temperature regime of 20°/30°C (16h/8h) is not entirely satisfactory however (5,13,14,18): 14°-15°/23°-25°C or 10°/20°C (15-16h/9-8h) are successful germination test regimes for B. erectus (12), B. inermis (13), B. mollis (13), B. sterilis (12) and B. tectorum (9). It is therefore suggested that seeds of Bromus accessions be tested for germination in the dark at 10°/20°C or 15°/25°C (16h/8h). Where this is not sufficient to promote full germination it is suggested that the seeds be pre-chilled and/or deglumed prior to testing in either regime.

VII. References

1. Coukos, C.J. (1944). Seed dormancy and germination in some native grasses. Journal of the American Society of Agronomy, 36, 337-34 5.

2. Drake, V.C. (1949). Germination of rescue grass seed as affected by temperature, substrata, light and removal of glumes. Newsletter of the Association of Official Seed Analysts, 23, 42-49.

3. Grime, J.P., Mason, G., Curtis, A.V., Rodman, J., Band, S.R., Mowforth, M.A.G., Neal, A.M. and Shaw, S. (1981). A comparative study of germination characteristics in a local flora. Journal of Ecology, 69, 1017-1059.

4. Heit, C.E. (1948). Report of subcommittee on dormancy in seeds. Proceedings of the Association of Official Seed Analysts, 38, 25-26.

5. Larsen, A.L., Montgillion, D.P. and Schroeder, E.M. (1973). Germination of dormant and non-dormant rescue grass seed on the thermogradient plate. Agronomy Journal, 65, 56-59.

6. Laude, H.M. (1956). Germination of freshly harvested seeds of some western range species. Journal of Range Management, 9, 126-129.

7. Nakamura, S. (1962). Germination of grass seeds. Proceedings of the International Seed Testing Association, 27, 710-729.

8. Nakamura, S., Watanabe, S. and Ichihara, J. (1960). Effect of gibberellin on the germination of agricultural seeds. Proceedings of the International Seed Testing Association, 25, 433-439.

9. Young, J.A. and Evans, R.A. (1982). Temperature profiles for germination of cool season range grasses. USDA Agricultural Research Service, Agricultural Research Results, Western Series No. 27.

10. Young, J.A., Evans, R.A. and Kay, B.L. (1973). Temperature requirements for seed germination in an annual-type rangeland community. Agronomy Journal, 65, 656-659.

11. Evans, R.A. and Young, J.A. (1975). Enhancing germination of dormant seeds of downy brome. Weed Science, 23, 354-357.

12. Froud-Williams, R.J. (1981). Germination behaviour of Bromus species and Alopecurus myosuroides. In Grass Weeds in Cereals in the United Kingdom, Conference, 1981, pp.31-40, Association of Applied Biology.

13. Grabe, D.F. (1955). Germination responses of smooth bromegrass seed. Proceedings of the Association of Official Seed Analysts, 45, 68-71.

14. Grabe, D.F. and Bass, L.N. (1954). Comparative methods of germinating smooth bromegrass. Proceedings of the Association of Official Seed Analysts, 44, 121-126.

15. Hilton, J.R. (1982). An unusual effect of the far-red absorbing form of phytochrome: photoinhibition of seed germination in Bromus sterilis L. Planta, 155, 524-528.

16. Hulbert, L.C. (1955). Ecological studies of Bromus tectorum and other annual bromegrasses. Ecological Monographs, 25, 181-213.

17. Koduru, T. (1967). [Studies on the germination of rescue grass, Bromus unioloides.] Bulletin of the Kyoto University of Education, B, 30, 21-30. (From Herbage Abstracts, 1968, 38, 1987.)

18. Steinbauer, G.P. and Grigsby, B.H. (1957). Field and laboratory studies of the dormancy and germination of the seeds of chess (Bromus secalinus L.) and downy bromegrass (Bromus tectorum L.). Weeds, 5, 1-4.

19. Stevens, O.A. (1923). The testing of bromegrass and wheatgrass seeds. Proceedings of the Association of Official Seed Analysts, 15, 120-123.

20. Thill, D.C., Schirman, R.D. and Appleby, A.P. (1980). Influence of afterripening temperature and endogenous rhythms on downy brome (Bromus tectorum) germination. Weed Science, 28, 321-323.

CHLORIS

C. ciliata
C. distichophylla
C. gayana Kunth	Rhodes-grass
C. orthonothon Doell
C. pycnothrix
C. truncata R. Br.	windmill grass
C. verticillata Nutt.

I. Evidence of dormancy

Dormancy has been reported in seeds of Chloris spp. (1,6-10). After-ripening seeds of C. pycnothrix and C. truncata for 5 months (10) and 48 weeks (6) respectively are reported to result in loss of dormancy.

II. Germination regimes for non-dormant seeds

C. gayana

TP: 20°/30°C; 20°/35°C (16h/8h): 14d (ISTA)

TP: 20°/30°C (16h/8h): 14d (AOSA)

Constant temperatures: 25°C in light (11)

III. Unsuccessful dormancy-breaking treatments

C. ciliata

Light: continuous dark (3,4,5)

C. orthonothon

Light: continuous dark (9); imbibition in dark at 25°C, 24h, then red light, 15 min (9)

C. pycnothrix

Light: continuous dark (10)

IV. Partly-successful dormancy-breaking treatments

C. ciliata

Light: imbibition in dark, 12°C, 24h, then light, 10 min to 7h at 33°C, germinate in dark (3,4,5)

Oxygen: (3,4,5)

C. distichophylla

Constant temperatures: 18°C, 23°C, 28°C, in continuous light or dark (8)

Warm stratification: 28°C, in dark, germinate at 18°C in light (8)

Potassium permanganate: pre-applied, 18°C or 28°C in dark, germinate at 18°C in light (8)

Sodium thiosulphate: pre-applied, 18°C or 28°C in dark, germinate at 18°C in light (8)

Sodium perborate: pre-applied, 18°C or 28°C in dark, germinate at 18°C in light (8)

Potassium iodate: pre-applied, 18°C or 28°C in dark, germinate at 18°C in light (8)

C. gayana

Alternating temperatures: 35°/15°C (18h/6h) (1); 20°/30°C, 20°/35°C (16h/8h) in light (7)

Potassium nitrate: co-applied, 0.2% (1,7)

Light: (7)

Removal of seed covering structures: (1)

Potassium nitrate: co-applied, 0.2%, at 20°/30°C, 20°/35°C (16h/8h) in light (7)

C. orthonothon

Scarification: concentrated sulphuric acid, 30-120s (9)

Light: dark, 24h, red light, 15 min, pre-dry, scarify (9)

Removal of seed covering structures: (9); dehull partly, imbibe in dark, 24h, red light, 15 min, then dark or far red light (9); dehull partly, imbibe in dark, 24h, then pre-soak, 40°C, 15-60 min, germinate at 25°C in dark (9)

C. truncata

Constant temperatures: 20°C, 25°C, 30°C (6)

Light: (6)

Removal of seed covering structures: (6)

C. verticillata

Alternating temperatures: 20°-25°/15°-20°C (day/night) (2)

Light: white or red, 30 min (2)

V. Successful dormancy-breaking treatments

C. ciliata

Removal of seed covering structures: (3,4,5)

Light: imbibe in dark at 12°C, 24h, then light at 33°C, 7.5h, germinate in dark (3,4,5)

C. gayana

Light, Potassium nitrate (AOSA, ISTA)

Removal of seed covering structures: deglume, plus potassium nitrate, co-applied, 0.2%, germinate at 35°/15°C (18h/6h) in light (1)

C. orthonothon

Removal of seed covering structures: dehull, imbide in dark, 25°C, 24h, then red light, 15 min, far red light, 15 min, red light, 15 min, germinate at 25°C in dark (9)

C. pycnothrix

Light: at 28°/14.5°C (day/night) (10)

VI. Comment

Light, particularly red light, promotes the germination of dormant seeds of Chloris spp. For dormant seeds of C. pycnothrix it appears that a high light intensity (direct sunlight) is required for germination since in a diffuse light regime (shaded from direct sunlight) percentage germination was reduced (10) - with no seeds germinating in the dark (10). However, the shading treatment - in a glasshouse - may have reduced the amplitude of the alternating temperature regime and it may have been this aspect of the germination test environment which caused the reduction in the proportion of seeds germinating. Unfortunately the ISTA and AOSA prescriptions for C. gayana are unlikely to be successful for the more dormant seed lots (7). It is suggested that it may be possible to improve these prescriptions by first degluming the seeds and then testing either as prescribed by AOSA/ISTA or at 35°/15°C (18h/6h) in light - see Chapter 6 - with 0.2% potassium nitrate co-applied. This regime may prove satisfactory for accessions of other Chloris spp.

VII. References

1. Cullinan, B. (1941). Germinating seeds of southern grasses. Proceedings of the Association of Official Seed Analysts, 33, 74-76.

2. Feltner, K.C. and Vesecky, J.F. (1968). Light quality and temperature effects on weed seed germination in two Kansas soils. Transaction of Kansas Academy of Sciences, 71, 7-12.

3. Gassner, G. (1910). Uber Keimungbedingugen einiger Südamerikanischer Gramineensamen, I, II. Berichte der Deutschen Botanischen Gesellschaft, 28, 350-364, 504-512.

4. Gassner, G. (1911). Keimuntersuchungen mit Chloris ciliata. Berichte der Deutschen Botanischen Gesellschaft, 29, 708-722.

5. Gassner, G. (1912). Untersuchungen über die Wirkung des Lichtes und des Temperaturewechsels auf die Keimung von Chloris ciliata. Jahrb. Hamberg, Wiss., 29, 1-121.

6. Lodge, G.M. and Whalley, R.D.B. (1981). Establishment of warm- and cool-season native perennial grasses on the north-west slopes of New South Wales. I. Dormancy and germination. Australian Journal of Botany, 29, 111-119.

7. Sharir, A. (1971). Germination temperatures of dormant and non-dormant Rhodes grass seed. Proceedings of the International Seed Testing Association, 36, 109-113.

8. Shimizu, N., Tajima, K. and Ogata, R. (1970). [Studies on promotion of germination at low temperature in tropical grass seed. I. Promotion of germination at low temperature in seeds of Chloris spp. and Eragrostis spp.] Bulletin of the National Grassland Research Institute, 11, 47-56.

9. Solange, M., Cruz, D. and Takaki, M. (1983). Dormancy and germination of seeds of Chloris orthonothon. Seed Science and Technology, 11, 323-329.

10. Fenner, M. (1980). Germination tests on thirty-two East African weed species. Weed Research, 20, 135-138.

11. Watt, L.A. and Whalley, R.D.B. (1982). Establishment of small-seeded perennial grasses on black clay soils in North-western New South Wales. Australian Journal of Botany, 30, 611-623.

CYMBOPOGON

C. caesius (Nees) Stapf
C. jwarancusa (Jones) Schult.
C. martinii (Roxb.) Wats.	rosha grass
C. martinii Stapf var Motia	palmarosa
C. olivieri (Boiss.) Bor
C. parkeri Stapf

I. Evidence of dormancy

In one investigation seed lots of C. caesius, C. jwarancusa, C. martinii, C. olivieri and C. parkeri were germinate d without special treatment within a comparatively short time (1) indicating little or no dormancy, but a separate investigation with seeds of C. martinii var Motia did show evidence of dormancy (2).

II. Germination regimes for non-dormant seeds

C. jwarancusa

Constant temperatures: room temperature, 14d (1)

C. olivieri

Constant temperatures: room temperature, 25d (1)

C. parkeri

Constant temperatures: room temperature, 14d (1)

III. Unsuccessful dormancy-breaking treatments

-

IV. Partly-successful dormancy-breaking treatments

C. martinii var Motia

Removal of seed covering structures: glumes (2)

V. Successful dormancy-breaking treatments

-

VI. Comment

It is suggested that seeds of Cymbopogon spp. be tested for germination on top of filter papers at 25°C for 14 days. Then remove the glumes from seeds which have not germinated within this period and test those seeds containing embryos for a further 14 days at 25°C and record the proportion of empty seeds. The empty seed proportion can be substantial for Cymbopogon spp. accessions.

VII. References

1. Ahmed, M., Hussain, A. and Hussain, T. (1978). Studies on some range grasses of Pakistan. Pakistan Journal of Forestry, 28, 7-12.

2. Nair, N.R. and Nair, N.G. (1981). Seed germination in palmarosa (Cymbopogon martini Stapf var Motia). Agricultural Research Jou rnal of Kerala, 19, 115-116.

CYNODON

C. dactylon (L.) Pers. [Panicum dactylon L.]	star grass, Bahama grass, Bermuda grass, doob
C. plectostachyum (Schum.) Pilger [C. dactylon var aridis Harlan & de Wet]	giant star grass

I. Evidence of dormancy

In 1918 C. dactylon seeds were described as some of the most difficult of agricultural seeds to germinate (3), and this species is still causing problems in seed testing laboratories (1). It appears that seed dormancy is not such a major problem in C. plectostachyum and that - when present - germination can be promoted more easily than is the case for C. dactylon (10).

II. Germination regimes for non-dormant seeds

C. dactylon

TP: 20°/35°C; 20°/30°C (16h/8h): 21d (ISTA)

TP: 20°/35°C (16h/8h): 21d (AOSA)

Constant temperatures: 25°C (7,13)

Alternating temperatures: 10°/40°C (16h/8h) (7); 10°-15°/40°C, 15°-20°/30°C, 20°/30°-40°C (16h/8h) (13)

C. plectostachyum

TP: 20°/35°C (16h/8h): L: 21d (AOSA)

III. Unsuccessful dormancy-breaking treatments

C. dactylon

Constant temperatures: 2°-10°C (13); 10°-38°C, dark (8); 20°C (1); 20°-35°C (5)

Pre-chill: 5°-10°C, 0-4w, dehulled seeds, germinate at 20°/30°C (16h/8h) in light with potassium nitrate, co-applied, 0.2% (1); 5°-10°C, 10d (10)

Scarification: concentrated sulphuric acid, 1-7 min (2); concentrated sulphuric acid, 5 min (4); sandpaper (4)

Pre-dry: 70°C, 17h (4)

Potassium nitrate: co-applied, 0.04, 1 N, at 32°C (8); co-applied, 0.2, 1-5% (10)

Sodium nitrate: co-applied, 0.04, 1 N, at 32°C (8); co-applied, 2.5, 5% (10)

Sodium nitrite: co-applied, 0.1, 1 N, at 32°C (8)

Nitric acid: co-applied, 0.01 N, at 32°C (8)

Ammonium nitrate: co-applied, 0.01 N, at 32°C (8)

GA₃: pre-applied, 24h, 7x10^-5 -2.8x10^-4 M, dehulled seeds (13)

Kinetin: pre-applied, 24h, 2.5x10^-6-2x10^-5 M, dehulled seeds (13)

C. plectostachyum

Alternating temperatures: 20°/30°C, 30°/20°C (6h/18h) (10)

Scarification: sulphuric acid, 75, 85%, 1 min (11); sandpaper (11)

IV. Partly-successful dormancy-breaking treatments

C. dactylon

Constant temperatures: 15°-40°C, dehulled seeds (13)

Alternating temperatures: 20°/30°C (16h/8h) (1); 22°-26°/33°C (18h/6h) (2); 15°/25°C, 15°/30°C, 15°/35°C, 20°/35°C, 25°/35°C (16.5h/7.5h) (5); 15°/35°C (16h/8h) (6); 20°/30°C, 20°/35°C, 30°/20°C, 35°/20°C (6h/18h) (10)

Pre-chill: 5°-10°C, 1-4w (1); 5°-10°C, 4w, dehulled seeds, germinate at 20°/30°C (16h/8h) in light (1)

Potassium nitrate: co-applied, 0.2% (1,6); co-applied, 0.1, 0.01 M (8); co-applied, 0.2%, dehulled seeds (1); co-applied, 0.1, 0.25% (10); pre-applied, 24h, 1% (2); pre-applied, 24h, 0.1, 1%, dehulled seeds (13)

Sodium nitrate: co-applied, 0.04, 0.01 M-(8)

Sodium nitrate: co-applied, 0.1%-1% (10)

Scarification: concentrated sulphuric acid, 1.5-9 min, dehulled seeds (8); concentrated hydrochloric acid, 5 min (4); concentrated sulphuric acid, 10 min (3); sulphuric acid, 75-100%, 1 min (11); nitric acid, 75-100%, 1 min (11); sandpaper (11)

Pre-soak: 24h (2); 24h, at 30°-40°C or 10°/40°C (16h/8h), germinate at 25°C (13)

Light: dark (12); fluorescent (12)

C. plectostachyum

Alternating temperatures: 20°/35°C, 35°/20°C (6h/18h) (10)

Pre-chill: 5°-10°C, 10d (10); 5°-10°C, 2-3w, plus potassium nitrate, co-applied, 0.2% (10)

Potassium nitrate: co-applied, 0.2% (10)

Light: dark (12)

Scarification: concentrated sulphuric acid, 1 min (11); sandpaper (11)

V. Successful dormancy-breaking treatments

C. dactylon

Light, Pre-chill, Potassium nitrate (AOSA, ISTA)

Alternating temperatures: 10°/38°C, 15°/38°C (18h/6h) (8); 10°-15°/40°C, 15°-20°/30°C, 20°/30°-40°C (16h/8h), dehulled seeds (13)

Potassium nitrate: co-applied, 0.2%, at 15°/35°C (16h/8h) (6); co-applied, 0.01 N, at 22°/32°C or 22°/38°C (18h/6h) in light (8); pre-applied, 24h, 10^-3 M, plus GA₃, 3.5x10^-5 M, plus kinetin, 10^-5 M, pre-applied, 24h, dehulled seeds, germinate at 10°/40°C (16h/8h) (7,13)

Sodium nitrate: co-applied, 10^-2 N, at 22°/32°C or 22°/38°C (18h/6h) in light (8)

Sodium nitrite: co-applied, 10^-2 N, at 22°/32°C or 22°/38°C (18h/6h) in light (8)

Ammonium nitrate: co-applied, 10^-2 N, at 22°/32°C or 22°/38°C (18h/6h) in light (8)

Oxygen: 8-12% (9)

C. plectostachyum

Pre-chill and then test at 25°/35°C (16h/8h), 21d (or 14d if dehulled), Potassium nitrate (AOSA)

VI. Comment

Even with non-dormant seeds of these species problems may arise. Potassium nitrate, co-applied, 0.2%, with germination in light at 20°/30°C (16h/8h) (1) or 15°/35°C (16h/8h) appear to be satisfactory regimes for some, but not all, seed lots. The general problem with most dormancy-breaking treatments reported here is that they may be very successful in promoting the germination of some seed lots but will reduce germination in others (e.g. 10). It is suggested that seeds of Cynodon spp. be tested for germination at 20°/35°C (16h/8h) in light with potassium nitrate, co-applied, 0.2%, with removal of the seed covering structures where required.

VII. References

1. Ahring, R.M. and Todd, G.W. (1978). Seed size and germination of hulled and unhulled bermudagrass seeds. Agronomy Journal, 70, 667 -670.

2. Akamine, E.K. (1944). Germination of Hawaiian range grass seeds. Hawaii Agricultural Experiment Station Technical Bulletin No. 2, 60 pp.

3. Bryan, W.E. (1918). Hastening the germination of Bermuda grass seed by the sulphuric acid treatment. Journal of the American Society of Agronomy, 10, 279-281.

4. Burton, G.W. (1939). Scarification studies on southern grass seeds. Journal of the American Society of Agronomy, 31, 179-187.

5. Harrington, G.T. (1923). Use of alternating temperatures in the germination of seeds. Journal of Agricultural Research, 23, 295-332.

6. Heit, C.E. (1948). Report of subcommittee on dormancy in seeds. Proceedings of the Association of Official Seed Analysts, 38, 25-26.

7. Kay, B.L., Evans, R.A. and Young, J.A. (1977). Soaking procedures and hydroseeder damage to common Bermudagrass seeds. Agronomy Journal, 69, 555-557.

8. Morinaga, T. (1926). Effect of alternating temperatures upon the germination of seeds. American Journal of Botany, 13, 141-158.

9. Morinaga, T. (1926). The favorable effect of reduced oxygen supply upon the germination of certain seeds. American Journal of Botany, 13, 159-166.

10. Okigbo, B.N. (1964). Studies of seed germination in star grasses: I. The effect of nitrate and alternating temperature. Journal of the West African Science Association, 8, 141-158.

11. Okigbo, B.N. (1964). Studies of seed germination in star grasses: II. Effect of mechanical and acid scarification. Journal of the West African Science Association, 8, 159-166.

12. Okigbo, B.N. (1964). Studies of seed germination in star grasses: III. Effects of mulching on germination in soil and light quality and fungicides on germination in petri dishes. Journal of the West African Science Association, 8, 167-179.

13. Young, J.A., Kay, B.L. and Evans, R.A. (1977). Accelerating the germination of common Bermudagrass for hydroseeding. Agronomy Journal, 69, 115-119.

DACTYLIS

D. glomerata L.

cocksfoot, orchard grass

I. Evidence of dormancy

Freshly harvested seeds of D. glomerata can show considerable dormancy (1,6-10,13-16). Dormancy may persist in the seeds after three years storage at room temperature (1) and is a problem in seed testing (1,9). Apparently non-dormant seeds have been reported to show great variation in repeated germination tests at 24°C (12).

II. Germination regimes for non-dormant seeds

TP: 15°/25°C; 20°/30°C (16h/8h): 21d (ISTA)

TP; TS: 15°/25°C (16h/8h): 21d (AOSA)

III. Unsuccessful dormancy-breaking treatments

Constant temperatures: 25°C (14); 20°C in light, 8h/d (9)

Alternating temperatures: 30°/25°C (12h/12h) (14); 20°/15°C (day/night) in light, 8h/d (9)

Light: dark, continuous (15); fluorescent, 8-24h/d (15)

Potassium nitrate: co-applied (1,7)

GA₃: co-applied, 100 ppm (7)

Germination in soil: (1)

IV. Partly-successful dormancy-breaking treatments

Constant temperatures: 15°C, 20°C (1,14); 10°-30°C, in light, 1500 lux (6); 16°C in light (15); 20°C (7)

Alternating temperatures: 20°/30°C, 15°/25°C (16h/8h) (1); 5°/18°C, 27°/18°C, 24°/18°C (1-4h/20-23h) (6); 22°/28°C (18h/6h) (8); 15°/25°C, 15°/30°C, 20°/30°C, 15°/35°C (16.5h/7.5h) (5); 20°/30°C, 20°/25°C, 15°/20°C (night/day) (9); 20°/30°C (16h/8h) (10,13); 15°/10°C, 20°/15°C, 25°/20°C (12h/12h) (14); 21°/11°C (12h/12h) (15,16)

Pre-chill: (7); 4°C, 1-6w (6)

GA₃: co-applied, 50-1000 ppm (6); pre-applied, 24h, 800-1000 ppm (6)

Kinetin: co-applied, 200-1610 ppm (6)

6-Benzylaminopurine: co-applied, 200-1610 ppm (6)

Mercuric chloride: pre-applied, 16h, 0.05-0.5% (2)

Lead nitrate: pre-applied, 16h, 0.1-1% (2)

Oxalic acid: pre-applied, 16h, 0.5-2% (2)

Sodium chloride: pre-applied, 16h, 1-6% (2)

Copper sulphate: pre-applied, 16h, 0.25-2.5% (2)

Magnesium chloride: pre-applied, 16h, 1-6% (2)

Pre-soak: 17h, then pre-dry, 15°C, 24h (3,4)

Removal of seed covering structures: lemma and palea (6,7); lemma and palea, then pre-chill, 5°C, 7d (1)

Light: (7); fluorescent, 4h/d (15)

V. Successful dormancy-breaking treatments

Pre-chill, Potassium nitrate (ISTA)

Light, Pre-chill, test in soil (AOSA)

Alternating temperatures: 15°/35°C (16h/8h) in light (7); 15°/28°C, 10°/28°C, 5°/28°C (18h/6h) (8); 15°/25°C (16h/8h) in light (11,13)

Pre-chill: 5°C, 7d, germinate at 15°/25°C (16h/8h) (1); 5°C, 10°C, 15°C, 14d, germinate at 22°/28°C (18h/6h) (8); 5°C, 7-10d, germinate at 20°/30°C (16h/8h) (10); 5°C, 5d, germinate at 15°/25°C, 20°/30°C (16h/8h) (13); 2°C, 21d (14)

Pre-soak: 17h, then pre-dry, 15°C, 24h (2)

Uspulun: pre-applied, 16h, 0.05-0.25% (2)

Orthophosphoric acid: pre-applied, 16h, 0.08-1.6% (2)

Magnesium phosphate: pre-applied, 16h, 0.66-4% plus manganese sulphate, 0.33-2% (2)

Removal of seed covering structures: lemma and palea, germinate at 20°/30°C (16h/8h) (1)

GA₃: co-applied, 400-1000 ppm (6); pre-applied, 1000ppm (6)

VI. Comment

Dormant seeds of D. glomerata require alternating temperatures and light for germination (1,6,7,15,16). The optimum photoperiod is 4 hours light per day (15). The ISTA prescribed alternating temperature regime of 20°/30°C is unsatisfactory (1,9,10,13), even for after-ripened seed lots (1). The following AOSA/ISTA procedure - pre-chill at 5°C for 7 days, then test at 15°/25°C for 21 days - is satisfactory for moderately-dormant or non-dormant accessions (1,10,13). It is suggested that these treatments be applied, but with light applied for 4 hours per day during the germination test. For the more dormant accessions it is suggested that, in addition, the lemmas and paleas be removed from seeds which fail to germinate during the first 14 days of the test.

VII. References

1. Canode, C.L., Horning, E.V. and Maguire, J.D. (1963). Seed dormancy in Dactylis glomerata L. Crop Science, 3, 17-19.

2. Chippindale, H.G. (1933). The effect of some chemicals on germination in cocksfoot (Dactylis glomerata L.). Annals of Applied Biology, 20, 369-376.

3. Chippindale, H.G. (1933). The effect of soaking in water on the "seeds" of Dactylis glomerata L. Annals of Botany, 47, 841-849.

4. Chippindale, H.G. (1933). The effect of soaking in water on the "seeds" of some gramineae. Annals of Applied Biology, 21, 225-232.

5. Harrington, G.T. (1923). Use of alternating temperatures in the germination of seeds. Journal of Agricultural Research, 23, 295-3 32.

6. Junttila, O. (1977). Dormancy in disperal units of various Dactylis glomerata populations. Seed Science and Technology, 5, 463-471.

7. Nakamura, S. (1962). Germination of grass seeds. Proceedings of the International Seed Testing Association, 27, 710-729.

8. Sprague, V.G. (1940). Germination of freshly harvested seeds of several Poa species and of Dactylis glomerata. Journal of the American Society of Agronomy, 32, 715-721.

9. Bean, E.W. (1976). Problems of germination in ecotypes of Dactylis glomerata. Welsh Plant Breeding Station, Report for 1975, 53.

10. Fendall, R.K. and Canode, C.L. (1971). Dormancy-related growth inhibitors in seeds of orchard-grass (Dactylis glomerata L.) Corp Science, 11, 727-730.

11. Haight, J.C. and Grabe, D.F. (1972). Wetting and drying treatments to improve the performancy of orchard grass seed. Proceedings of the Association of Official Seed Analysts, 62, 135-148.

12. Kummerow, J. (1963). Endogenous fluctuations of germination capacity in Dactylis glomerata. American Journal of Botany, 50, 915-920.

13. Maguire, J.D. and Canode, C.L. (1963). Germination of Latar and Pennlate orchardgrass. Proceedings of the Association of Official Seed Analysts, 53, 92-95.

14. Pannangpetch, K. and Bean, E.W. (1984). Effects of temperature on germination in populations of Dactylis glomerata from NW Spain and Central Italy. Annals of Botany, 53, 633-639.

15. Probert, R.J., Smith, R.D. and Birch, P. (1985). Germination responses to light and alternating temperatures in European populations of Dactylis glomerata L. I. Variability in relation to origin. New Phytologist, 99, 305-316.

16. Probert, R.J., Smith, R.D. and Birch, P. (1985). Germination responses to light and alternating temperatures in European populations of Dactylis glomerata L. II. The genetic and environmental components of germination. New Phytologist, 99, 317-322.

DIGITARIA

D. adscendens (HBK) Henrad.
D. chinensis Hornem.
D. didactyla
D. exilis Stapf	hungry rice, fonio, fundi, acha
D. ischaemum (Schreber) Muhl.	smooth finger-grass
D. milanjiana (Rendle) Stapf
D. pentzii Stent.
D. sanguinalis (L.) Scop.	hairy finger-grass, crabgrass
D. scalarum (Schweif.) Chiov.	blue couch grass
D. smutsii
D. violascens Link

I. Evidence of dormancy

Dormancy has been reported in seed lots of D. adscendens (4,15-17,19), D. chinensis (17), D. didactyla (9), D. exilis (3), D. ischaemum (5,6), D. milanjiana (7,8), D. pentzii (8), D. sanguinalis (1,2,5,6,10,11), D. scalarum (12,13) and D. violescens (17). After-ripening periods required to remove dormancy in seed lots of Digitaria spp. can be considerable; for example 1300 days for D. adscendens (16) and 18 months for D. scalarum (12), whilst two-year-old seeds of D. didactyla can remain dormant (9). The severity of dormancy in Digitaria spp. causes problems in breeding programmes (8).

II. Germination regimes for non-dormant seeds

D. ischaemum

Alternating temperatures: 20°/35°C, 20°/40°C, 20°/30°C (18h/6h) (6)

D. sanguinalis

Alternating temperatures: 20°/35°C, 20°/30°C, 20°/40°C (18h/6h) in light (6)

D. smutsii

TP: 20°/30°C (16h/8h): 10d (ISTA)

III. Unsuccessful dormancy-breaking treatments

D. adscendens

Constant temperatures: 20°C, 30°C (16,17)

Pre-chill: 3°C, 30d (17)

GA₃: co-applied, 10, 25 ppm (20)

Scarification: concentrated sulphuric acid, 2,5 min (20)

Light: (17)

D. exilis

Pre-soak: 24h (3)

D. ischaemum

Light: (6)

Scarification: concentrated sulphuric acid, 2 min (6)

D. milanjiana

Alternating temperatures: 10°/20°C, 10°/30°C, 20°/30°C (12h/12h) in light (7)

GA₃: co-applied, 50-800 ppm (7,8)

Thiourea: co-applied, 10^-2 M (7)

Potassium nitrate: co-applied, 10^-2 M (7)

D. pentzii

GA₃: co-applied, 50-800 ppm (8)

D. sanguinalis

Oxygen: (1); 5-98% (2)

Potassium nitrate: co-applied, 0.2% (6)

IV. Partly-successful dormancy-breaking treatments

D. adscendens

Alternating temperatures: 20°/30°C (4); 20°/30°C (10h/14h) (17); 30°C/room temperature (10h/14h) (15,16); 25°±3°/35±3°C (17)

Warm stratification: 20°C, 30d, germinate at 20°/30°C (10h/14h) (17)

GA₃: co-applied, 5 ppm (20)

Removal of seed covering structures: dehull (16,19); dehull, then endosperm (16); cut off top of hull (16)

Light: (4)

D. chinensis

Alternating temperatures: 25°±3°/35±3°C (17)

Warm stratification: 20°C, 30d, germinate at 20°/30°C (10h/14h) (17)

D. didactyla

Alternating temperatures: 20°/35°C, 15°/35°C (10h/14h) (9)

Light: 14h/d, at 35°C or 20°/35°C, 15°/35°C (10h/14h) (9)

D. exilis

Potassium cyanide: pre-applied, 24h, 10^-3 M (3)

Sodium azide: pre-applied, 24h, 10^-3 M (3)

Hydroxylamine hydrochloride: pre-applied, 24h, 10^-3 M (3)

D. ischaemum

Alternating temperatures: 20°/40°C, 20°/35°C, 20°/30°C, 15°/25°C (18h/6h), 8w (6)

Pre-chill: 2°-5°C, 14,28d (6)

Ethanol: pre-applied, 7d, 50x10^-6 1 (in a 125 ml flask), in dark at 35°C, germinate at 20°/30°C (16h/8h) in red light, 3.3x10^-9 mol cm^-2 s^-1 (5)

Potassium nitrate: co-applied, 0.2% (6)

Scarification: sand paper (6); concentrated sulphuric acid, 0.5, 1 min (6)

1,2-Dibromo-3-chloropropane: co-applied, 10 ppm (18)

D. milanjiana

Removal of seed covering structures: dehull (7,8); dehull then endosperm (7); chip (8)

GA₃: co-applied, 10-800 ppm, dehulled seeds (7,8)

Thiourea: co-applied, 10^-2 M, dehulled seeds (7)

Potassium nitrate: co-applied, 10^-2 M, dehulled seeds (7)

D. pentzii

Removal of seed covering structures: dehull (8); chip (8)

GA₃: co-applied, 50-800 ppm, dehulled seeds (8)

D. sanguinalis

Alternating temperatures: 15°/30°C (16h/8h) (1); 20°/40°C, 20°/30°C, 15°/25°C (18h/6h), 8w (6)

Pre-chill: 10°C, 5d (1); 2°-5°C, 14-56d (6); 14°C, 2-3m (14)

Light: (6); 9h/d (1); 100-200 fc (2)

Potassium nitrate: co-applied, 0.25% (1)

Ethylene chlorohydrin: pre-applied, 24,48h, 0.5-0.125% (1); pre-applied, 48h, 25-250, 1000 ppm (10)

Pre-soak: (1)

Removal of seed covering structures: dehull (14); caryopses scarified (2); caryopses scarified plus oxygen, 40-98% (2)

Ethanol: pre-applied, 7d, 50x10^-61 (in a 125 ml flask), in dark at 35°C, germinate at 20°/30°C (16h/8h) in red light, 3.3x10^-9 mol cm^-2 s^-1 (5)

GA₃: co-applied, 100, 1000 ppm (11)

1,2-Dibromo-3-chloropropane: co-applied, 10 ppm (18)

D. scalarum

Alternating temperatures: 20°/30°C (night/day) in diffuse light (13); 15°/23°C, 20°/29°C (night/day) (12)

Scarification: (12); concentrated sulphuric acid, 5 min (13); mechanical (13)

D. violascens

Alternating temperatures: 25°±3°/35±3°C (17)

Warm stratification: 20°C, 30d, germinate at 20°/30°C (10h/14h) (17)

V. Successful dormancy-breaking treatments

D. ischaemum

Alternating temperatures: 20°/35°C, 20°/40°C (18h/6h), 5m (6)

Pre-chill: 2°-5°C, 56d, germinate at 20°/35°C (18h/6h) (6)

D. sanguinalis

Alternating temperatures: 20°/30°C (18h/6h) in light, 3m (6); 20°/35°C (18h/6h), 3m (6)

Pre-chill: 2°-4°C, 56d, in light (1)

Ethylene chlorohydrin: pre-applied, 48h, 500 ppm (2, 10)

Removal of seed covering structures: (1); puncture (2, 10)

D. smutsii

Pre-chill, Potassium nitrate (ISTA)

VI. Comment

Two month pre-chill treatments at about 3°C appear to be satisfactory for D. ischaemum (6) and D. sanguinalis (1). Of those tested, the most suitable subsequent alternating temperature regimes for germination are between 20°/35°C and 20°/40°C (18h/6h) (6). However substantial periods in test may be required for full germination, viz. 140 days for D. ischaemum and 75d for D. sanguinalis (6).

The promotion of germination of the most dormant seeds of D. milanjiana and D. pentzii is likely to prove more difficult (7,8). Suggested additional treatments are dehulling plus co-application of gibberellic acid at 100 ppm. In addition prick and re-prick the firm seeds which remain in test.

VII. References

1. Delouche, J.C. (1956). Dormancy in seeds of Agropyron smithii, Digitaria sanguinalis, and Poa pratensis. Iowa State College Journal of Science, 30, 348-349.

2. Gianfagna, A.J. and Pridham, A.M.S. (1951). Some aspects of dormancy and germination of crabgrass seed, Digitaria sanguinalis Scop. Proceedings of the American Society for Horticultural Science, 58, 291-297.

3. Roberts, E.H. (1964). The distribution of oxidation-reduction enzymes and the effects of respiratory inhibitors and oxidising agents on dormancy in rice seed. Physiologia Plantarum, 17, 14-29.

4. Takabayashi, M. and Nakayama, K. (1981). [The seasonal change in seed dormancy of main upland weeds.] Weed Research, Japan, 26, 249-253.

5. Taylorson, R.B. and Hendricks, S.H. (1979). Overcoming dormancy in seeds with ethanol and other anesthetics. Planta, 145, 507-510.

6. Toole, E.H. and Toole, V.K. (1941). Progress of germination of seed of Digitaria as influenced by germination temperature and other factors. Journal of Agricultural Research, 63, 65-90.

7. Baskin, J.M., Shank, S.C. and West, S.H. (1967). Studies on germination and dormancy of Digitaria milanjiana (Rendle) Stapf from tropical Africa. Proceedings of Soil and Crop Science Society of Florida, 27, 90-96.

8. Baskin, J.M., Shank, S.C. and West, S.H. (1969). Seed dormancy in two species of Digitaria from Africa. Crop Science, 9, 58 4-586.

9. Febles, G. and Harty, R. (1973). Effect of light and alternate temperatures on the germination of Digitaria didactyla. Cuban Journal o f Agricultural Science, 7, 233-236.

10. Gianfagna, A.J. and Pridham, A.M.S. (1952). Some aspects of dormancy and germination of crabgrass seed, Digitaria sanguinalis Scop. Proceedings of the North Eastern Weed Control Conference, 6, 321-326.

11. Gray, R.A. (1958). Breaking the dormancy of peach seeds and crabgrass seeds with gibberellins. Plant Physiology, 33, 40-41.

12. Harker, K.W. (1957). A note on Digitaria scalarum seed. East African Agricultural Journal, 23, 109.

13. Huxley, P.A. and Turk, A. (1966). Factors which affect the germination of seeds of six common East African weeds. Experimental Agriculture, 2, 17-25.

14. Martin, J.N. (1943). Germination studies of the seeds of some common weeds. Proceedings of the Iowa Academy of Science, 50, 221-2 28.

15. Matumura, M. and Hirayoshi, I. (1961). [Physiological and ecological studies on germination of Digitaria seeds. II. Changes in germinability with elapsing of stored period on five lines of Mehisiba (D. adscendens Henrad) through successive generations.] Gifu University Faculty of Agriculture Research Bulletin, 14, 78-88.

16. Matumura, M. and Hirayoshi, I. (1962). [Physiological and ecological studies on germination of Digitaria seeds. III. A function of the caryopsis and hulls on appearing the individual difference of germinability.] Gifu University Faculty of Agriculture Research Bulletin, 16 104-111.

17. Matumura, M., Takase, N. and Hirayoshi, I. (1960). [Physiological and ecological studies on germination of Digitaria seeds. I. Differences in response to germinating conditions and dormancy among individual plants.] Gifu University Faculty of Agriculture Research Bulletin, 12, 89-96.

18. Miller, P.M., Ahrens, J.F. and Stoddard, E.M. (1965). Stimulation of crabgrass seed germination by 1,2-dibromo-3-chloropropane and ethylene dibromide. Weeds, 13, 13-14.

19. Shimizu, M. (1959). [Relation of the enclosing structure of the Digitaria adscendens spikelet to its germination. 2. The role of the enclosing structure (glumes and shell coat) of crabgrass (D. adscendens) and rice-plant spikelets in the absorption of water and water soluble substances.] Proceedings of the Crop Science Society of Japan, 28, 239-243. (From Horticultural Abstracts, 1960, 30, 1662.)

20. Singhal, B.K. and Sen, D.N. (1981). Seed germination in some grasses of Indian desert. Forage Research, 7, 27-30.

ECHINOCHLOA

E. colona (L.) Link [E. colonum Link; Panicum colonum L.]	jungle rice, shama millet
E. crus-galli (L.) Beauv. [Panicum crus-galli]	barnyard millet
E. frumentacea (Roxb.) Link [Panicum frumentaceum Roxb.]	japanese barnyard millet, sanwa millet, billion-dollar grass
E. utilis

I. Evidence of dormancy

Seeds of E. colona (5,19), E. crus-galli (5,8,9,15-17,21-27) and E. frumentacea (1,6) can show considerable dormancy at harvest and may require 2-8 months after-ripening for dormancy to be lost (19).

II. Germination regimes for non-dormant seeds

E. crus-galli

TP: 20°/30°C (16h/8h); 25°C: 10d (ISTA)

Constant temperatures: 25°C (11); 30°C (14)

Alternating temperatures: 15°-20°/30°C, 15°/35°C, 15°-25°/40°C (16h/8h) (14)

E. frumentacea

TP: 20°/30°C (16h/8h): 10d (AOSA)

III. Unsuccessful dormancy-breaking treatments

E. colona

Light: dark (19)

Urea: co-applied, 0.5% (5)

E. crus-galli

Constant temperatures: 10°C (20); 20°C, dark (26); 30°C, dark (21)

Alternating temperatures: 20°/30°C (16h/8h) in light (24)

Warm stratification: 30°C, 7d (24)

Pre-soak: 24,48h (21)

Light: (21,27); dark (8,9,19,26)

Removal of seed covering structures: lemma and palea (27)

Oxygen: (17); 0%, scarified seeds (27); 100% (27)

Ammonium chloride: co-applied, 10^-2 M (2)

Thiourea: co-applied, 0.2% (5); pre-applied, 24h, 10^-1-10^-3 M (21,22)

Potassium nitrate: co-applied, 0.3% (5)

Indoleacetic acid: co-applied, 50, 100 ppm (7)

Kinetin: co-applied, 50, 100 ppm (7)

Sodium sulphide: pre-applied, 24h, 10^-2-10^-4 M (21)

8-Hydroxyquinoline: pre-applied, 24h, 10^-3, 10^-4 M (21)

Phenylthiourea: pre-applied, 24,48h, 10^-2, 10^-3 M (22)

2,3-Dimercapto-1-propanol: pre-applied, 24,48h, 0.1, 0.01% (22)

Hydroxylamine: pre-applied, 24,48h, 10^-2, 10^-3 M (22); pre-applied, 24h, 10^-1-10^-3 M (21)

Salicylaldoxime: pre-applied, 24h, 10^-1-10^-3 M (21)

Salicylic acid: pre-applied, 24h, 10^-2 M (25)

Sodium diethyldithiocarbamate: pre-applied, 24h, 10^-1-10^-3 M (21)

p-Nitrophenol: pre-applied, 24h, 10^-2-10^-4 M (21)

Benzoquinone: pre-applied, 24h, 10^-2, 10^-3 M (25); pre-applied, 48h, 10^-4 M (25)

Malonic acid: pre-applied, 24h, 10^-2 M (25)

Ascorbic acid: pre-applied, 24h, 10^-1, 10^-2 M (21,23)

Cysteine: pre-applied, 24h, 10^-1, 10^-2 M (23)

Glutathione: pre-applied, 24h, 10^-2, 10^-3 M (23)

Ethrel: pre-applied, 24h, 10-1000 ppm (21)

Catechol: pre-applied, 24h, 10^-2, 10^-3 M (21)

E. frumentacea

Pre-chill: 5°C, 7d (1,6)

Potassium nitrate: co-applied, 0.2% (6)

GA₃: co-applied, 100 ppm (6)

IV. Partly-successful dormancy-breaking treatments

E. colona

Light: continuous (19)

Potassium nitrate: co-applied, 0.3% (5)

Thiourea: co-applied, 0.25% (5)

E. crus-galli

Constant temperatures: 10°-42°C (9)

Alternating temperatures: (9); 30°/15°C (15); 20°/30°C in light (8,20); 5°/30°C (13); 5°/25°C (12); 5°/30°-35°C, 20°/30°-35°C (16); 8°/25°C in light (18)

Pre-chill: 5°C (9,21); 1°C, 5°C, 10°C, 2m (12); 10°C, 2m (26)

Potassium nitrate: co-applied, 10^-2 M (2)

Sodium nitrate: co-applied, 10^-3 M (2)

Hydroxylamine hydrochloride: co-applied, 3.2x10^-4 M (2)

Potassium nitrite: co-applied, 10^-5 M (2)

Urea: co-applied, 2.5x10^-2-10^-1 M (17)

Scarification: sulphuric acid (9); sulphuric acid, 2 N, 15 min (27); sodium hydroxide, 2 N, 15-60 min (27)

Removal of seed covering structures: lemma and palea (9,21,25); lemma, palea and pericarp (27)

Light: (8,13,15,18,20); 1 min (9); 4x10^-4 W m^-2, 5 min (12)

Ethanol: pre-applied, 3d, 0.5 M, at 35°C, 5 min red light, germinate at 20°/30°C (16h/8h) (10)

Pre-soak: 4-120h (16)

Pre-dry: 50°C, 14d, germinate at 20°/30°C (16h/8h) in light (24)

Oxygen: 20-100%, scarified seeds (27)

Calcium cyanamide: co-applied, 10^-3-10^-1 M (17)

Potassium cyanide: pre-applied, 24h, 10^-2 M (21,25); pre-applied, 24,48h, 10^-2, 10^-3 M (22)

Sodium azide: pre-applied, 24h, 10^-2 M (21,22)

Sodium cyanide: pre-applied, 24h, 10^-2 M (25)

Sodium sulphide: pre-applied, 48h, 10^-2, 10^-3 M (22)

Hydroquinone: pre-applied, 24h, 10^-1 M (21,22,25)

8-Hydroxyquinoline: pre-applied, 24,48h, 10^-2 -10^-4 M (25)

Benzoquinone: pre-applied, 24h, 10^-2 M (23); pre-applied, 48h, 10^-2, 10^-3 M (25)

8-Oxyquinoline: pre-applied, 24,48h, 10^-2 M (22,25)

Mercuric chloride: pre-applied, 24h, 10^-2 M (21,22,25); pre-applied, 48h, 10^-2, 10^-3 M (22)

2-4 Dinitrophenol: pre-applied, 24h, 10^-2 M (21); pre-applied, 48h, 0.1% (25)

Sodium diethyldithiocarbamate: pre-applied, 48h, 10^-1 M (22)

Salicylaldoxime: pre-applied, 48h, 10^-2 M (22)

E. frumentacea

Alternating temperatures: (6); 10°/15°C, 20°/25°C, 25°/30°C (night/day) (3)

Thiourea: co-applied, 0.2% (6)

E. utilis

Alternating temperatures: 10°/15°C, 20°/25°C, 25°/30°C (night/day) (3)

V. Successful dormancy-breaking treatments

E. colona

Light: continuous (19)

E. crus-galli

Pre-dry (ISTA)

Alternating temperatures: 20°-30°/5°C, 30°/15°C (day/night) in light (15)

Pre-chill: 5°C, 6m (15); 1°C, 5°C, 2m (26)

Liquid nitrogen: 5 min, then thaw, 1h, 10 cycles (4)

Pre-dry: 50°C, 14d, then warm stratifiction, 30°C, 7d, germinate at 20°/30°C (16h/8h) in light (24)

Light: 1 min (9)

Removal of seed covering structures: lemma, palea and pericarp (9); excise embryo, test on agar (27)

Potassium cyanide: co-applied, 5x10^-3 -10^-1 M (17)

Sodium cyanide: co-applied, 5x10^-3 -10^-1 M (17)

E. frumentacea

Alternating temperatures: 20°/30°C, 15°/25°C (16h/8h) in light (1)

Pre-dry: 35°C, 7d, germinate at 20°/30°C (16h/8h) (1)

VI. Comment

Although long pre-chill treatments - 2 to 6 months at 5°C for example - can promote the germination of dormant seeds of weedy Echinochloa spp., quite short pre-chill treatments - 7 days at 5°C for example - can be detrimental to less dormant or non-dormant seeds of the cultivated Echinochloa spp. (15,26). Consequently pre-chilling cannot be used as a general dormancy-breaking procedure for all Echinochloa accessions. Light and alternating temperatures are essential for germination (8-10,13,15,16,18,20,24): 20°/30°C (16h/8h) in light is a satisfactory regime for partly-dormant accessions (1), but does not promote full germination of dormant seeds of weedy Echinochloa spp. (16,20,24). In these cases lemma and palea removal or pricking near the embryo are suggested. Where this is inadequate pre-drying with subsequent warm stratification may be a useful additional procedure (24).

VII. References

1. Harper, L.W. (1970). Dormancy in Japanese millet (Echinochloa crus-galli var. Frumentacea (Roxb.) Wight) seed. Proceedings of the Association of Official Seed Analysts, 60, 132-137.

2. Hendricks, S.B. and Taylorson, R.B. (1974). Promotion of seed germination by nitrate, nitrite, hydroxylamine, and ammonium salts. Plant Physiology, 54, 304-309.

3. Hughes, R.M. (1979). Effects of temperature and moisture stress on germination and seedling growth of four tropical species. Journal of the Australian Institute of Agricultural Science, 45, 125.

4. Jordan, J.L. (1981). Seed dormancy in Pennsylvania smart weed and barnyard grass. Dissertation Abstracts International, B, 42, 1256-1257.

5. Moursi, M.A., Rizk, T.Y. and El-deepah, H.R. (1977). Weed seed germination responses to some chemical treatments. Egyptian Journal of Agronomy, 2, 197-209.

6. Nakamura, S. (1962). Germination of grass seeds. Proceedings of the International Seed Testing Asosciation, 27, 710-729.

7. Rizk, T.Y., Fayed, M.T. and El-Deepah, H.R. (1978). Effect of some promoters on weed seed germination. Research Bulletin, Faculty of Agriculture, Ain Shamo University, 818, 30pp.

8. Takabayashi, M. and Nakayama, K. (1981). [The seasonal change in seed dormancy of main upland weeds.] Weed Research, Japan, 26, 249-253.

9. Takahashi, H. (1978). Seed germination, ecology and cultivation of barnyard grass after italian ryegrass in unflooded paddy fields. Japan Agricultural Research Quarterly, 12, 44-48.

10. Taylorson, R.B. and Hendricks, S.B. (1979). Overcoming dormancy in seeds with ethanol and other anaesthetics. Planta, 145, 507-510.

11. Vanderzee, D. and Kennedy, R.A. (1981). Germination and seedling growth in Echinochloa crus-galli var. oryzicola under anoxic conditions: structural aspects. American Journal of Botany, 68, 1269-1277.

12. Watanabe, Y. (1978). [Physiological and ecological studies on upland weeds in Hokkaido.] Research Bulletin of The Hokkaido National Agricultural Experimental Station, 123, 17-77.

13. Watanabe, Y. (1981). [Ecological studies on seed germination and emergence of some summer annual weeds of Hokkaido.] Weed Research, Japan, 26, 193-199. (From Seed Abstracts, 1982 5, 2738.)

14. Arai, M. and Miyahara, M. (1963). [Physiological and ecological studies on barnyard grass (Echinochloa crus-galli Beauv. var oryzicola Ohwi.). V. On the germination of the seed.] Proceedings of the Crop Science Society of Japan, 31, 362-366.

15. Furya, S. and Kataoka, T. (1983). The effect of temperature and soil moisture on innate dormancy-breaking in Echinochloa spp. and temperature and light conditions for their germination. Aspects of Applied Biology, 4, 55-62.

16. Hayashi, M. and Kuroki, O. (1973). [Studies on the seed dormancy and breaking of seed dormancy of barnyard grass (Echinochloa crus-galli Beauv. var oryzicoia Ohwi.).] Japanese Journal of Tropical Agriculture, 16, 276-282.

17. Inoue, K., Higashi, T. and Yamasaki, K. (1970). [Control of barnyard grass using the dormancy breaking effect of calcium cyanamide. 1. The action of dormancy breaking of respiration inhibitory agents and gases to barnyard grass seeds.] Journal of the Science of Soil and Manure, 41, 377-382.

18. Popova, D. (1979). [Effect of light at constant and variable temperature conditions on the germination of green amaranth (Amaranthus retroflexus (L.) R. et S.) and barnyard grass (Echinochloa crus-galli L.) seeds.] Plant Science, 16, 39-48.

19. Ramakrishnan, P.S. (1960). Ecology of Echinochloa colonum Link. Indian Academy of Science Proceedings B, 52, 73-90.

20. Roché, B.F. Jr. and Muzik, T.J. (1964). Ecological and physiological study of Echinochloa crus-galli (L.) Beauv. and the response of its biotypes to sodium 2,2-dichloropropionate. Agronomy Journal, 56, 155-160.

21. Shimizu, N., Takahashi, H. and Tajima, K. (1974). [Effect of some artificial treatments and various chemicals as oxidase inhibitors on breaking seed dormancy in Echinochloa crus-galli var caudata.] Journal of Japanese Society of Grassland Science, 20, 173-180.

22. Shimizu, N. and Ueki, K. (1972). [Studies on the breaking of dormancy in barnyard grass seed. 3. Change of the dormancy-breaking effect of several inhibitors against oxidation-reduction system with dormancy stage.] Proceedings of the Crop Science Society of Japan, 41, 480-487.

23. Shimizu, N. and Ueki, K. (1972). [Studies on the breaking of dormancy in barnyard grass seed. 3. Change of the dormancy-breaking effect of various compounds concerned with the oxidation-reduction system by dormancy stage.] Proceedings of the Crop Science Society of Japan, 41, 488-495.

24. Taylorson, R.B. (1980). Aspects of seed dormancy in fall panicum (Panicum dichotomiflorum). Weed Science, 28, 64-67.

25. Ueki, K. and Shimuzu, N. (1969). [Studies on the breaking of dormancy in barnyard grass seed. 1. The effects of various chemicals on the breaking of dormancy.] Proceedings of the Crop Science Society of Japan, 38, 261-272.

26. Watanabe, Y. and Hirokawa, F. (1979). [Ecological studies on the germination and emergence of annual weeds. 1. Effect of temperatures on the dormancy breaking in seeds of Chenopodium album, Echinochloa crus-galli var praticola and Polygonum lapathifolium.] Weed Research, Japan, 17, 24-28.

27. Yamasue, Y., Sudo, K. and Ueki, K. (1977). Physiological studies on seed dormancy of barnyard grass (Echinochloa crus-galli Beauv. var Oryzicola Ohwi.). Proceedings of the 6th Asian-Pacific Weed Science Society Conference, Indonesia 1977, 1, 42-51.

ELEUSINE

E. compressa
E. coracana (L.) Gaertn. [Cynosurus coracanus, L.; E. coracan Aschers. & Graebn.]	finger millet, African millet, koracan, ragi, wimbi, bulo, telebun
E. indica (L.) Gaertn.	goose grass, fowl-foot grass
E. tristachya Lam.

I. Evidence of dormancy

Germinating seeds of E. coracana as a routine procedure in seed testing stations can be particularly difficult (1). Variation in dormancy between cultivars can be considerable (11,12). In the more dormant cultivars dormancy may remain after seven months after-ripening at room temperature (8,11,12). As might be expected the weed/pasture Eleusine spp. can show considerably more dormancy than E. coracana.

II. Germination regimes for non-dormant seeds

E. coracana

TP: 20°/30°C (16h/8h): 8d (ISTA)

Constant temperatures: 30°C, 5d (2)

Alternating temperatures: 20°/30°C (16h/8h), 14d (A)

III. Unsuccessful dormancy-breaking treatments

E. compressa

Pre-dry: 110°C, 3-4h (5)

Scarification: concentrated sulphuric acid, 1 min (5)

Light: (5)

E. coracana

Alternating temperatures: (8)

Light: (2,8)

Potassium chloride: co-applied, 0.1% (8)

Ammonium chloride: co-applied, 0.2% (8)

Ammonium sulphate: co-applied, 0.1% (8)

Thiourea: co-applied, 0.2% (8)

Potassium nitrate: co-applied, 0.01% (8)

GA₃: co-applied, 100 ppm (8,9)

Ammonium thiocyanate: co-applied, 0.01% (8)

Ethylene chlorohydrin: co-applied, 0.0001% (8)

E. indica

Constant temperatures: 10°C, 15°C, 20°C (13); 15°-35°C in dark (4); 28°-50°C (3)

Alternating temperatures: 15°/25°C (17h/7h) (13)

Pre-chill: 4°C, 4w (10); 3°C, 2-8w (13)

Potassium nitrate:co-applied, 0.2%, in light (13)

Light: (3)

IV. Partly-successful dormancy-breaking treatments

E. compressa

Constant temperatures: 35°C in dark (5)

Pre-dry: 100°C, 2h (5)

E. coracana

Constant temperatures: 30°C in light, continuous (11,12)

Pre-chill: 5°C, 5d (8); 5°C, 7, 15d, plus potassium nitrate, co-applied, 0.2% (8)

Nitric acid: co-applied, 0.001-0.5% (8)

Sodium nitrate: co-applied, 0.01-0.5% (8)

Ammonium nitrate: co-applied, 0.01-0.5% (8)

Sodium nitrate: co-applied, 0.2% (8)

Aluminium nitrate: co-applied, 0.2% (8)

Magnese nitrate: co-applied, 0.2% (8)

Magnesium nitrate: co-applied, 0.1% (8)

Potassium nitrate: co-applied, 0.1% (8)

Ethylene chlorohydrin: co-applied, 0.1% (8)

Scarification: concentrated sulphuric acid, 4 min (8)

Removal of seed covering structures: lemma and palea (14)

E. indica

Alternating temperatures: 20°/30°C (16h/8h) in light (13); 4°C/ambient temperature (19h/5h) (10); 31.5°/23°C (12h/12h) in dark or light (6); 20°/28°C, 20°/30°C, 20°/40°C (16h/8h) with or without potassium nitrate, co-applied, 0.2% (3)

GA₃: co-applied, 0.01%, at 31.5°/23°C (12h/12h) in light (6)

Potassium nitrate: co-applied, 0.2%, at 31.5°/23°C (12h/12h) in light (6); co-applied, 0.2%, at 30°C (3)

Scarification: mechanical, with or without potassium nitrate, co-applied, 0.2% (13)

Removal of seed covering structures: lemma and palea (14)

E. tristachya

Removal of seed covering structures: lemma and palea (14)

V. Successful dormancy-breaking treatments

E. coracana

Potassium nitrate (ISTA)

Potassium nitrate: co-applied, 0.05-0.5%, at 25°C (8)

Calcium nitrate: co-applied, 0.1% (8)

Barium nitrate: co-applied, 0.2% (8)

Potassium nitrite: co-applied, 0.2% (8)

Scarification: concentrated sulphuric acid, 2 min, germinate at 25°C (8)

E. indica

Potassium nitrate: co-applied, 0.2%, at 30°C in light (4); co-applied, 0.2%, at 20°/30°C, 20°/35°C (16h/8h) in light (3,4); co-applied, 0.2% at 20°/35°C, 25°/40°C, 20°/40°C (17h/7h) (13)

GA₃: co-applied, 0.1%, at 31.5°/23°C (12h/12h) in light (7)

Removal of seed covering structures: prick (10)

Pre-soak: 7d (3)

VI. Comment

It has been suggested that a constant temperature of 30°C results in a greater proportion of seeds of E. coracana germinating than an alternating temperature of 20°/30°C (1), but this conclusion is possibly a result of the short test period, 5 days. For non-dormant seeds the latter regime is suitable (A). It has further been suggested that no procedure is satisfactory for seed testing and that instead a tetrazolium test should be performed (1). However, it is suggested here that seeds of Eleusine spp. be tested for germination in an alternating temperature regime of 20°/30°-35°C (16h/8h) in light with potassium nitrate co-applied at 0.2% with pricking of ungerminated seeds near the embryo after a few days in test.

VII. References

1. Agrawal, P.K. and Kaur, S. (1975). Standardisation of the tetrazolium test for ragi (Eleusine coracana) seeds. Seed Science and Technology, 3, 565-568.

2. Arora, N. and Banerjee, S.K. (1978). Seed testing procedure for finger millet (Eleusine coracana). Seed Research, 6, 158-160.

3. Chin, H.F. and Raja Harum, R.M. (1979). Ecology and physiology of Eleusine indica seeds. Proceedings of the 7th Asian-Pacific Weed Science Society Conference, Sydney, Australia, 313-315.

4. Fulwider, J.R. and Engel, R.E. (1959). The effect of temperature and light on germination of seed of goosegrass, Eleusine indica. Weeds, 7, 359-361.

5. Gupta, R.K. and Saxena, S.K. (1980). Ecological studies on Eleusine compressa - a potential grass for sheep pasturage in the arid zone. Annals of Arid Zone, 19, 1-14.

6. Hawton, D. (1979). Temperature effects on Eleusine indica and Setaria anceps grown in association. Weed Research, 19, 279-284.

7. Hawton, D. and Drennan, D.S.H. (1980). Studies on the longevity and germination of seed of Eleusine indica and Crotalaria goreensins. Weed Research, 20, 217-223.

8. Nakamura, S. (1962). Germination of grass seeds. Proceedings of the International Seed Testing Association, 27, 710-729.

9. Nakamura, S., Watanabe, S. and Ichihara, J. (1960). Effect of gibberellin on the germination of agricultural seeds. Proceedings of the International Seed Testing Association, 25, 433-439.

10. Popay, A.I. (1973). Germination and dormancy in the seeds of certain East African weed species. Proceedings of the 4th Asian-Pacific Weed Science Society Conference, 1, 77-81.

11. Shimizu, N. and Mochizuki, N. (1978). [Studies on dormancy and germination of seed in finger millet (Eleusine coracana). 2. Varietal differences of degree of dormancy and germination behaviour.] Bulletin of the National Grassland Research Institute (Japan), 12, 76-91.

12. Shimizu, N. and Tajima, K. (1979). [Studies on dormancy and germination of seed in finger millet (Eleusine coracana). 1. Effect of light, temperature and their interaction on germination.] Journal of Japanese Society of Grassland Science, 24, 289-295.

13. Toole, E.H. and Toole, V.K. (1940). Germination of seed of goosegrass, Eleusine indica. Journal of the American Society of Agronomy, 32, 320-321.

14. Hilu, K.W. and Wett, J.M.J. de (1980). Effect of artificial selection on grain dormancy in Eleusine (Gramineae). Systematic Botany, 5, 54-60.

ERAGROSTIS

E. abyssinica (Jacq.) Link [E. tef (Zucc.) Trotter; Poa abyssinica Jacq.]	teff, t'ef
E. brizantha Nees
E. cilianensis
E. curvula (Schrad.) Nees	weeping lovegrass
E. ferruginea Beauv.
E. lehmanniana Nees	Lehmann lovegrass
E. leptoschachya (Steud.) Blake	lovegrass
E. secundiflora Presl
E. trichodes (Nutt.) Wood	sand lovegrass

I. Evidence of dormancy

E. abyssinica seeds show some dormancy at harvest. This is most clearly seen from the duration of the germination test required at 30°C for full germination: freshly harvested seeds require 6-10 weeks, whereas old (after-ripened) seeds require only 3-7 days (6). Other Eragrostis spp. can exhibit considerable seed dormancy (1,3,5,8,9,16,18,20,21,24).

II. Germination regimes for non-dormant seeds

E. abyssinica

TP: 20°/30°C (16h/8h): 10d (ISTA)

Constant temperatures: 30°C (6)

Alternating temperatures: 20°/30°C (18h/6h) (13)

E. curvula

TP: 15°/30°C; 20°/35°C (16h/8h): 10d (ISTA)

TP: 20°/35°C (16h/8h): 14d (AOSA)

E. lehmanniana

Constant temperatures: 25°C, 30°C (16)

Alternating temperatures: 20°/30°C in light, 15°/25°C, 25°/35°C (16h/8h) (5,16)

E. trichodes

TP: 20°/30°C (16h/8h): 14d (AOSA)

III. Unsuccessful dormancy-breaking treatments

E. abyssinica

Pre-chill: 3°-5°C, 4-8w (13)

Potassium nitrate: co-applied, 0.2% (13)

E. curvula

Constant temperatures: 15°-25°C (9)

Pre-chill: 3°-5°C, 4-8w (13)

Potassium nitrate: co-applied, 0.2% (9,13)

GA₃: co-applied, 100 ppm (9,10)

Thiourea: co-applied, 0.2% (9)

Light: (9); dark (14)

E. ferruginea

Light: dark, 6-12h, then red, 10 min, then dark 18-12h, then fluorescent, 12h (17); dark, 6-12h, then far red, 10 min, then dark 18-12h, then fluorescent, 12h (17); dark at 27°C (18,19,21)

5-Bromouracil: co-applied, 10^-4-1.6x10^-2 M (18)

5-Fluorouracil: co-applied, 10^-4-10^-1 M (18)

E. lehmanniana

Pre-chill: 3°-5°C, 4-8w (13)

GA₃: (3,5,16)

Kinetin: (3,5,16)

Indoleacetic acid: (3,5,16)

Thiourea: (3,5,16)

Gamma radiation: (3,5,16)

High frequency electrical field: (3,16)

Sodium hydroxide: pre-applied, 24 min +, 1 N (5)

Pre-wash: (5)

Potassium nitrate: (3,16)

E. leptoschachya

Removal of seed covering structures: (8)

IV. Partly-successful dormancy-breaking treatments

E. abyssinica

Alternating temperatures: 20°/40°C (18h/6h) (13)

Constant temperatures: 30°C (6)

E. cilianensis

Ethanol: pre-applied, 0.5 M, 35°C, 3d, 5 min red light, germinate at 20°/30°C (16h/8h) (12)

E. curvula

Constant temperatures: 30°C (9,14)

Alternating temperatures: 30°/15°C (16h/8h) (9); 2°/7°C, 7°/13°C in light (15)

Pre-chill: 5°C, 4d (9)

Light: (11,14,15); dark (9); dark, 8h, then fluorescent, 60-400 fc, 2 min (25); dark, 8h, then fluorescent, 4000 fc, 0-32 min (25)

Potassium permanganate: pre-applied (11)

Sodium thiosulphate: pre-applied (11)

Sodium perborate: pre-applied (11)

Potassium iodate: pre-applied (11)

Chlorinated lime: pre-applied (11)

Potassium nitrate: co-applied, 0.2% (13)

E. ferruginea

Light: dark, 24h, then 1000-2000 lux, 12h (7,17,18,20,21); dark, 24h, then 100, 200 lux, 21h/d (22)

Methanol: pre-applied, 1-12h, germinate at 27°C in light (21)

Acetone: pre-applied, 6-48h, germinate at 27°C in light (21)

E. lehmanniana

Constant temperatures: 15°C (5,13); 20°C (5); 29°C (11)

Alternating temperatures: 20°/30°C (16h/8h) in light (3); 20°/30°C (18h/6h) in light (16); 15°/25°C, 20°/30°C, 25°/35°C, 25°/40°C (23)

Pre-chill: 5°-10°C, 2-15w (16)

Sodium hydroxide: pre-applied, 24 min, 1 N, (3,5,16)

Scarification: sulphuric acid, 1 N, 30-100 min (3,5,16); cylinder, 7-12 min (3,5,16); mechanical (4); needle (5,16)

Light: (11); dark, 24h, then light (3)

Potassium nitrate: co-applied, 0.2% (13)

Pre-soak: 16°C, 36h (2); 28°C, 18h (2); 20-100 min, with agitation (3,5,16)

Potassium permanganate: pre-applied (11)

Sodium thiosulphate: pre-applied (11)

Sodium perborate: pre-applied (11)

Potassium iodate: pre-applied (11)

Chlorinated lime: pre-applied (11)

E. leptoschachya

Constant temperatures: 20°-25°C (8)

Light: (8)

E. secundiflora

Alternating temperatures: 20°/40°C (18h/6h) (13)

Pre-chill: 3°-5°C, 14d (13)

Potassium nitrate: co-applied, 0.2% (13)

E. trichodes

Alternating temperatures: 20°/30°C (16h/8h) (1); 20°/40°C (18h/6h)(13)

Pre-chill: 5°-10°C, 14d (1); 3°-5°C, 4-8w (13)

Potassium nitrate: co-applied, 0.1% (1); co-applied, 0.2% (13)

Calcium nitrate: co-applied, 0.2% (1)

Ammonium nitrate: co-applied, 0.2% (1)

Pre-dry: 90°-100°C, 30-40 min (1); 50°-60°C, 12-24h (1)

V. Successful dormancy-breaking treatments

E. abyssinica

Pre-chill, Potassium nitrate (ISTA)

Constant temperatures: 30°C, 70d (6)

Alternating temperatures: 20°/30°C (16h/8h) in light (13)

Potassium nitrate: co-applied, 0.2%, at 20°/30°C in light or 20°/40°C (18h/6h) (13); co-applied, 0.2%, plus pre-chill, 3°-5°C, 14d (13)

E. curvula

Pre-chill, Potassium nitrate (ISTA)

Light, Potassium nitrate (AOSA)

Alternating temperatures: 20°/30°C in light, 20°/40°C, 25°/40°C (18h/6h) (13)

Light: dark, 1-3d, then light (14); dark, 24h, then fluorescent, 60-4000 fc, 2 min (25); dark, 24h, then red, 600 erg cm^-2 s^-1, 8 min (25)

E. ferruginea

Methanol: pre-applied, 24h, germinate in light (21)

Removal of seed covering structures: puncture (21)

Pre-dry: 6-18d, germinate at 27°C in light, continuous (21)

Nitrogen: 100%, 36h, then germinate in light (19)

E. lehmanniana

Constant temperatures: 25°C, 30°C, 35°C (5,16)

Alternating temperatures: 20°/30°C, 15°/25°C, 25°/35°C (16h/8h) (5,16)

Pre-chill: 3°-5°C, 28d, plus potassium nitrate, co-applied, 0.2%, at 20°/30°C (18h/6h) in light (13)

E. secundiflora

Potassium nitrate: co-applied, 0.2%, then pre-chill, 3°-5°C, 14d, germinate at 20°/40°C (18h/6h) (13)

E. trichodes

Light, Pre-chill, Potassium nitrate (AOSA)

Potassium nitrate: co-applied, 0.2%, then pre-chill, 14d, germinate at 20°/40°C (18h/6h) (13); co-applied, 0.2%, then pre-chill, 28d, germinate at 30°/5°-15°C in light (24)

VI. Comment

Light can both promote and inhibit the germination of dormant and slightly dormant seeds of Eragrostis spp. Light treatments are particularly promotory when applied after the seeds have imbibed in the dark for 24 hours (7,17-22,25), but can be inhibitory when applied during the first 8 hours of imbibition (17,25). Testing slightly dormant seeds of E. abyssinica in an alternating temperature regime of 20°/30°C (16h/8h) in the light (8h/d) with 0.2% potassium nitrate co-applied is very satisfactory: in our laboratory this regime, which involves combining 3 stimulatory agents, has been very successful in promoting the full germination of accessions showing residual dormancy (A). In view of the above comment on the light regime, however, it is suggested that the light treatment should not be applied during the first 24 hours of the germination test. For accessions of E. lehmanniana testing at 20°/30°C (16h/8h) in the light with 0.2% potassium nitrate co-applied is also proposed but after 28 days pre-chilling at 3°-5°C (13). It is suggested that the AOSA/ISTA prescriptions be applied for E. curvula and E. trichodes, but without light on the first day of the test. The AOSA recommend a 6 week pre-chill treatment at 5° to 10°C for dormant seeds of E. trichodes.

VII. References

1. Ahring, R.M., Dun, N.L. and Harlan, J.R. (1963). Effect of various treatments in breaking seed dormancy in sand lovegrass, Eragrostis trichodes (Nutt.) Wood. Crop Science, 3, 131-133.

2. Bleak, A.T. and Keller, W. (1972). Germination and emergence of selected forage species following preplanting seed treatment. Crop Science, 12, 9-13.

3. Brauen, S.E. (1967). Seed coat histology, germination dormancy and seedling drought tolerance of Lehmann lovegrass (Eragrostis lehmanniana Nees). Dissertation Abstracts, 28B, 436.

4. Haferkamp, M.R. (1975). Some physiological and physical changes exhibited by seeds of lehmann lovegrass (Eragrostis lehmanniana Nees) with presowing seed treatments of moistening and drying. Dissertation Abstracts, 36B, 1011.

5. Haferkamp, M.R., Jordan, G.L. and Matsuda, K. (1977). Pre-sowing seed treatments, seed coats and metabolic activity of Lehmann lovegrass seeds. Agronomy Journal, 69, 527-530.

6. Katayama, T.C. and Nakagama, A. (1972). Studies on the germination behaviour of teff seeds (Eragrostis abyssinica Schrad.) with the emphasis of storage condition. Japanese Journal of Tropical Agriculture, 16, 97-105.

7. Isikawa, S., Fujii, T. and Yokohama, Y. (1961). Photoperiodic control of the germination of Eragrostis seeds. Botanical Magazine (Tokyo), 74, 14-18.

8. Lodge, G.M. and Whalley, R.D.B. (1981). Establishment of warm- and cool- season native perennial grasses on the North-West slopes of New South Wales. I. Dormancy and germination. Australian Journal of Botany, 29, 111-119.

9. Nakamura, S. (1962). Germination of grass seeds. Proceedings of the International Seed Testing Association, 27, 710-729.

10. Nakamura, S., Watanabe, S. and Ichihara, J. (1960). Effect of gibberellin on the germination of agricultural seeds. Proceedings of the International Seed Testing Association, 25, 433-439.

11. Shimizu, N., Tajima, K. and Ogata, R. (1970). [Studies on promotion of germination at low temperature in tropical grass seed. 1. Promotion of germination at low temperature in seeds of Chloris spp. and Eragrostis spp.] Bulletin of the National Grassland Research Institute, 11, 47-56. (From Seed Abstracts, 1978, 1, 2062.)

12. Taylorson, R.B. and Hendricks, S.B. (1979). Overcoming dormancy in seeds with ethanol and other anesthetics. Planta, 145, 507-510.

13. Toole, V.K. (1939). Germination requirements of the seed of some introduced and native range grasses. Proceedings of the Association of Official Seed Analysts, 30, 227-243.

14. Toole, V.K. and Borthwick, H.A. (1968). Light responses of Eragrostis curvula seed. Proceedings of the International Seed Testing Association, 33, 515-530.

15. Voigt, P.W. (1973). Induced seed dormancy in weeping lovegrass Eragrostis curvula. Crop Science, 13, 76-79.

16. Wright, L.N. (1973). Seed dormancy, germination environment, and seed structure of lehmann lovegrass, Eragrostis lehmanniana Nees. Crop Science, 13, 432-435.

17. Fujii, T. (1962). Studies on photoperiodic responses involved in the germination of Eragrostis seeds. Botanical Magazine (Tokyo), 75, 56-62.

18. Fujii, T. (1963). Inhibitory effect of 5-bromouracil and 5-fluorouracil on photoperiodically induced germination of Eragrostis seed. Plant and Cell Physiology, 4, 277-283.

19. Fujii, T. (1963). On the anaerobic process involved in the photoperiodically induced germination of Eragrostis seed. Plant and Cell Physiology, 4, 357-359.

20. Fujii, T. and Isikawa, S. (1962). Effects of after-ripening on photoperiodic control of seed germination in Eragrostis ferruginea Beauv. Botanical Magazine, Tokyo, 75, 296-301. (From Herbage Abstracts, 1963, 33, 854.)

21. Fujii, T. and Yokohama, Y. (1965). Physiology of light-requiring germination in Eragrostis seeds. Plant and Cell Physiology, 6, 135-145.

22. Isikawa, S. (1954). Light-sensitivity against the germination. I. "Photoperiodism" of seeds. Botanical Magazine (Tokyo), 64, 51-56.

23. Knipe, O.D. (1967). Influence of temperature on the germination of some range grasses. Journal of Range Management, 20, 298-299.

24. Sayers, R.L. (1969). Germination requirements of sand dropseed (Sporobolus cryptandrus) and sand lovegrass (Eragrostis trichodes). Dissertation Abstracts International, 30B, 1535-1536.

25. Toole, V.K. and Borthwick, H.A. (1968). The photoreaction controlling seed germination in Eragrostis curvula. Plant and Cell Physiology, 9, 125-136.

FESTUCA

F. arizonica Vasey	Arizona fescue
F. arundinacea Schreber	tall fescue
F. elatior L. [F. pratensis Huds.]	meadow fescue
F. elatior L. var apennina (De Not.) Hack.
F. idahoensis Elmer	Idaho fescue
F. megalura Nutt. [Vulpia megalura (Nutt.) Rydb.]	foxtail fescue
F. octoflora Walt.	sixweeks fescue
F. ovina L. var capillata Alef. [F. tenuifolia Hort.]	hair fescue
F. ovina L. var duriuscula Koch. [F. duriuscula L.; F. trachyphylla (Hack.) Krajina]	hard fescue
F. ovina L. var ovina [F. vulgaris Hort.]	sheep fescue
F. rubra L. var commutata Gaud. [F. rubra var fallax Hack.]	chewings fescue
F. rubra L. var rubra	red and creeping red fescue
F. scabrella Torr. ex Hook.	rough fescue

I. Evidence of dormancy

Freshly harvested seeds of Festuca spp. can present problems of dormancy (1,5-9,14,17-20).

II. Germination regimes for non-dormant seeds

F. arizonica

Constant temperatures: 15°C, 20°C (10)

Alternating temperatures: 15°/25°C, 20°/30°C (16h/8h) (10)

F. arundinacea

TP: 15°/25°C; 20°/30°C (16h/8h): 14d (ISTA)

TP: 15°/25°C; 20°/30°C (16h/8h): 14d (AOSA)

Constant temperatures: 18°-26°C (13)

F. elatior

TP: 15°/25°C; 20°/30°C (16h/8h): 14d (ISTA)

TP: 15°/25°C; 20°/30°C (16h/8h): 14d (AOSA)

F. idahoensis

Alternating temperatures: 15°/20°C, 20°/25°C (16h/8h) (10,11)

F. megalura

Constant temperatures: 15°C, 20°C (12)

Alternating temperatures: 5°/20°C, 15°/25°C (16h/8h) (12)

F. octoflora

Constant temperatures: 20°C (5)

Alternating temperatures: 15°/25°C (15h/9h) (5)

F. ovina var capillata

TP: 15°/25°C; 20°/30°C (16h/8h): 21d (ISTA)

TP: 10°/25°C (16h/8h): 28d (AOSA)

F. ovina var duriuscula

TP: 15°/25°C; 20°/30°C (16h/8h): 21d (ISTA)

TP: 15°/25°C (16h/8h): 21d (AOSA)

F. ovina var ovina

TP: 15°/25°C; 20°/30°C (16h/8h): 21d (ISTA)

TP: 15°/25°C (16h/8h): 21d (AOSA)

TP: 20°/30°C (16h/8h): 28d (AOSA)

F. rubra var commutata, F. rubra var rubra

TP: 15°/25°C; 20°/30°C (16h/8h): 21d (ISTA)

TP: 15°/25°C (16h/8h): 21d (AOSA)

F. scabrella

Constant temperatures: 15°C, 20°C (10)

Alternating temperatures: 15°/25°C, 20°/30°C (16h/8h) (10)

III. Unsuccessful dormancy-breaking treatments

F. arundinacea

Potassium nitrate: co-applied, 0.2% (9,17)

Thiourea: co-applied, 0.2% (9)

GA₃: co-applied, 100 ppm (9)

Kinetin: co-applied, 5x10^-5 M (14)

Sodium azide: co-applied (14)

F. elatior

GA₃: co-applied, 100 ppm (9)

F. elatior var apennina

Constant temperatures: 20°C (18)

F. octoflora

Constant temperatures: 20°C in light (5)

Alternating temperatures: 10°/30°C (15h/9h) in light (5,16)

Potassium nitrate: co-applied, 0.2% (5)

F. ovina var ovina

Constant temperatures: 3°C, 28d (4)

F. rubra var commutata

Potassium nitrate: co-applied, 0.2% (7,9)

GA₃: co-applied, 100 ppm (9)

Thiourea: co-applied, 0.2% (9)

Light: (7)

Pre-soak: 22°C, 17h, then pre-dry, 15°C, 24h (2)

F. rubra var rubra

Potassium nitrate: co-applied, 0.2% (9); co-applied, 2x10^-3, 2x10^-2 M (19)

Thiourea: co-applied, 0.2% (9)

GA₃: co-applied, 9000-35000 ppm (15)

IV. Partly-successful dormancy-breaking treatments

F. arundinacea

Constant temperatures: 15°C (1)

Alternating temperatures: 25°/30°C (16h/8h) (17)

Light: (3,9)

Pre-chill: 3°-5°C, 7d (6,9)

Potassium nitrate: co-applied, 0.2% (14)

GA₃: co-applied, 5x10^-4 M (14)

Removal of seed covering structures: (14)

F. elatior

Constant temperatures: 15°C (6,7); 20°C (18)

Alternating temperatures: 10°/30°C, 15°/30°C, 20°/30°C, 10°/25°C (18h/6h) (6,7)

Pre-chill: 5°C, 7-14d (6,7); 0°-2°C, 14d (8)

Light: (6,7,9)

Potassium nitrate: co-applied, 0.2% (6,7,9)

Pre-soak: 22°C, 17h, then pre-dry, 15°C, 24h (2)

F. elatior var apennina

Warm stratification: 20°C, 15d, then pre-chill, 2°C, 14d, germinate at 20°C (18)

F. octoflora

Alternating temperatures: 15°/30°C, 20°/30°C, 15°/25°C (15h/9h) in light (16)

Warm stratification: 20°C, 21d, in light, then pre-chill, 3°-5°C, 7d (5); 20°C, 21d, in light, plus potassium nitrate, co-applied, 0.2%, then pre-chill, 3°-5°C, 7d, germinate at 20°C in light (5)

Potassium nitrate: co-applied, 0.2%, at 10°C, 15°C, 15°/25°C (15h/9h) in light (16)

F. ovina var capillata

Constant temperatures: 10°C, 15°C, 20°C (6,7)

Alternating temperatures: 15°/25°C, 10°/30°C, 20°/30°C (18h/6h) (6,7)

Pre-chill: 5°C, 7, 14d (6,7,9,20)

Light: (6,7)

F. ovina var ovina

Constant temperatures: 10°C (4)

Light: (9)

Potassium nitrate: co-applied, 0.2% (9)

GA₃: co-applied, 100 ppm (9); co-applied, 10^-3 M (4)

F. rubra var commutata

Alternating temperatures: 10°/30°C, 15°/30°C, 20°/30°C (18h/6h) (6,7)

Pre-chill: 3°-5°C, 7d (6,7,9)

Pre-soak: 22°C, 17h, then pre-dry, 15°C, 24h (2)

Light: (9)

F. rubra var rubra

Constant temperatures: 10°C, 15°C (6,7); 20°C in light, red (19)

Alternating temperatures: 10°/30°C, 15°/30°C, 20°/30°C (18h/6h) (6,7)

Pre-chill: 5°C, 7,14d (6,7,9,20)

Potassium nitrate: co-applied, 0.2% (6,7); co-applied, 0.2%, at 20°C (20)

Light: (9); 5 min/d (20)

GA₃: co-applied, 100 ppm (9)

V. Successful dormancy-breaking treatments

F. arizonica

Constant temperatures: 15°C, 20°C (10)

Alternating temperatures: 15°/25°C, 20°/30°C (16h/8h) (10)

F. arundinacea

Pre-chill, Potassium nitrate (ISTA)

Light, Pre-chill, Potassium nitrate (AOSA)

Constant temperatures: 1°C, 5°C, 48d (1); 10°C, 24d (1)

Alternating temperatures: 10°-15°/20°-25°C (16h/8h) (1); 15°/25°C (16h/8h) (3,6); 15°/30°C (16h/8h) in light (9); 18°/28°C, 15°/30°C, 20°/30°C (16h/8h) (17)

Pre-chill: 1°C, 5°C, 10°C, 12-24d, germinate at 15°/25°C (16h/8h) (14); 10°C, 7d, germinate at 20°/30°C (16h/8h) in light (17)

F. elatior

Potassium nitrate, Pre-chill (ISTA)

Light, Potassium nitrate (AOSA)

Constant temperatures: 20°C, 15d, then pre-chill remaining seeds, 2°C, 14d, then germinate at 20°C (18)

Alternating temperatures: 15°/25°C (18h/6h) (6,7); 15°/30°C (16h/8h) (9)

Pre-chill: 3°-5°C, 7d (9)

Thiourea: co-applied, 0.2% (9)

F. elatior var apennina

Constant temperatures: 20°C, 15d, then pre-chill remaining seeds, 2°C, 14d, then germinate at 20°C (18)

Pre-chill: 0°-2°C, 28d (8)

F. idahoensis

Alternating temperatures: 15°/20°C, 20°/25°C (16h/8h) (10,11)

F. megalura

Constant temperatures: 10°C, 15°C, 20°C (12)

Alternating temperatures: 5°/20°C, 10°/20°C, 15°/20°C, 10°/25°C, 15°/25°C, 20°/25°C, 10°/30°C, 15°/30°C (16h/8h) (12)

F. octoflora

Constant temperatures: 20°C in light, 9h/d (16)

Potassium nitrate: co-applied, 0.2%, at 20°C in light, 9h/d (16)

F. ovina var capillata

Potassium nitrate, Pre-chill (ISTA)

Potassium nitrate (AOSA)

Alternating temperatures: 10°/25°C (18h/6h) (6,7)

Potassium nitrate: co-applied, 0.2%, at 10°/25°C (18h/6h) in light (6,7)

F. ovina var duriuscula

Potassium nitrate, Pre-chill (ISTA)

Light, Potassium nitrate (AOSA)

Constant temperatures: 15°C, 20°C (10)

Alternating temperatures: 15°/20°C, 15°/25°C, 20°/25°C (16h/8h) (10)

F. ovina var ovina

Potassium nitrate, Pre-chill (ISTA)

Light, Alternating temperatures: 15°/30°C (16h/8h) in light (9); 10°/20°C, 15°/20°C, 10°/25°C, 15°/25°C, 5°/20°C (16h/8h) (10, 11)

Pre-chill: 3°C, 7d (4,9)

Thiourea: co-applied, 0.2% (9)

F. rubra var commutata

Potassium nitrate, Pre-chill (ISTA)

Light, Potassium nitrate, Pre-chill (AOSA)

Constant temperatures: 15°C in light (9)

Alternating temperatures: 15°/30°C (16h/8h) (9); 15°/25°C (18h/6h) (6,7)

F. rubra var rubra

Potassium nitrate, Pre-chill (ISTA)

Light, Potassium nitrate, Pre-chill (AOSA)

Alternating temperatures: 15°/30°C (16h/8h) (9); 15°/25°C (18h/6h) (6,7); 12°/20°C (12h/12h) (19); 10°/20°C (15h/9h) (20); 5°-16°/20°C (12h/12h) in light, red, 1.4x10^-6 mol m^-2 s^-1, 10 min (19)

Pre-chill: 4°C, 21,42d (20)

F. scabrella

Constant temperatures: 15°C, 20°C (10)

Alternating temperatures: 15°/25°C, 20°/30°C (16h/8h) (10)

VI. Comment

For dormant seeds of F. octoflora (5) and F. ovina var capillata (6,7) potassium nitrate can be promotory, but for other Festuca spp. potassium nitrate is of little benefit provided the seeds are tested in a suitable temperature regime (6,7,9,17,19,20): that is the germination test temperature regime is the major factor which must be specified in order to promote the germination of dormant seeds of Festuca accessions. Accessions of F. octoflora which show partial dormancy show greater germination in 42 days when tested at a constant temperature of 20°C in light than at alternating temperature regimes of 20°/30°C or 15°/25°C (15h/9h) (5,16); the successful regimes listed for F. octoflora (above) are not sufficient, however, to promote full germination in freshly harvested seed lots (5). Accessions of other Festuca spp. require alternating temperatures for germination (1,2,6,7,9-11,17-20), but the standard alternating temperature regime of 20°/30°C (16h/8h) is not the most suitable (6,7,16,17,19). In a major study of the response of seed lots of many Festuca spp. to alternating temperatures an optimum regime of 15°/20°C (16h/8h) was discerned (10). Other studies suggest that this or 15°/25°C (16h/8h) are most suitable for germination tests (1,3,6,7,11,12,14) with the possible exceptions of F. ovina var ovina - where a wider range of optimum regimes (5°-15°/20°-25°C) has been suggested (10) - and F. ovina var capillata - where 10°/25°C has been proposed (6,7). For very dormant accessions which fail to germinate fully in these regimes (given sufficient time in test) pre-chilling for a prolonged period with 0.2% potassium co-applied is proposed.

VII. References

1. Boyce, K.G., Cole, D.F. and Chilcote, D.O. (1976). Effect of temperature and dormancy on germination of tall fescue. Crop Science, 16, 15-18.

2. Chippindale, H.G. (1933). The effect of soaking in water on the "seeds" of some gramineae. Annals of Applied Biology, 21, 225-232.

3. Danielson, H.R. and Toole, V.K. (1976). Action of temperature and light on the control of seed germination in alta tall fescue (Festuca arundinacea Schreb). Crop Science, 16, 317-320.

4. Harmer, R. and Lee, J.A. (1978). The germination and viability of Festuca vivipara (L.) Sm. plantlets. New Phytologist, 81, 745-751.

5. Hylton, L.O. Jr. and Bass, L.N. (1961). Germination of sixweeks fescue. Proceedings of the Association of Official Seed Analysts, 51, 118-124.

6. Kearns, V. and Toole, E.H. (1938). Temperature and other factors affecting the germination of the seed of fescues. Proceedings of the International Seed Testing Association, 10, 337-341.

7. Kearns, V. and Toole, E.H. (1939). Temperatures and other factors affecting the germination of fescue seed. USDA Technical Bulletin No. 638, pp. 35.

8. Linnington, S., Bean, E.W. and Tyler, B.F. (1979). The effects of temperature upon seed germination in Festuca pratensis var. apennina. Journal of Applied Ecology, 16, 933-938.

9. Nakamura, S. (1962). Germination of grass seeds. Proceedings of the International Seed Testing Association, 27, 710-729.

10. Young, J.A. and Evans, R.A. (1982). Temperature profiles for germination of cool season range grasses. USDA Agricultural Research Service, Agricultural Research Results, Western Series, No. 27.

11. Young, J.A., Evans, R.A., Eckert, R.E. Jr. and Ensign, R.D. (1981). Germination-temperature profiles for idaho and sheep fescue and Canby bluegrass. Agronomy Journal, 73, 716-720.

12. Young, J.A., Evans, R.A. and Kay, B.L. (1973). Temperature requirements for seed germination in an annual-type rangeland community. Agronomy Journal, 65, 656-659.

13. Bean, E.W. (1977). Effect of temperature on germination in Festuca arundinacea Schreb. Welsh Plant Breeding Station, Annual Report for 1976, pp.88-89.

14. Boyce, K.G. (1973). Seed dormancy in tall fescue (Festuca arundinacea Schreb.); acquisition, effect on metabolic process and relief by temperature and growth regulators. Dissertation Abstracts International B, 33, 5615-5616.

15. Button, E.F. (1959). Effect of gibberellic acids on laboratory germination of creeping red fescue (Festuca rubra). Agronomy Journal, 51, 60-61.

16. Hylton, L.O. Jr. and Bement, R.E. (1961). Effects of environment on germination and occurrence of sixweeks fescue. Journal of Range Management, 14, 257-260.

17. Stanway, V. (1952). A study made on laboratory germination of tall fescue seed. Proceedings of the Association of Official Seed Analysts, 42, 84-88.

18. Tyler, B., Borrill, M. and Chorlton, K. (1978). Studies in Festuca. X. Observations on germination and seedling cold tolerance in diploid Festuca pratensis and tetraploid F. pratensis var apennina in relation to their altitudinal distribution. Journal of Applied Ecology, 15, 219-226.

19. Williams, E.D. (1983). Effects of temperature fluctuation, red and far-red light and nitrate on seed germination of five grasses. Journal of Applied Ecology, 20, 923-935.

20. Williams, E.D. (1983). Effects of temperature, light, nitrate and pre-chilling on seed germination of grassland plants. Annals of Applied Biology, 103, 161-172.

HORDEUM

H. glaucum Steud.
H. jubatum L.	foxtail barley, squirrel-tail grass
H. leporinum Link
H. marinum Huds. [H. maritimum Stokes]	sea barley
H. murinum L.	wall barley
H. pusillum Nutt.	little barley
H. spontaneum Koch
H. vulgare L. [H. sativum Pers.; H. distichon L.; H. distichum L.; H. hexastichon L.; H. polystichon Hall.]	barley

I. Evidence of dormancy

Of the common temperate cereals dormancy in H. vulgare is probably the most pronounced. This can cause problems both in seed testing and the malting industry. Dormancy is also common in H. geniculatum (30), H. glaucum (30), H. jubatum (34,36), H. leporinum (25,30,33), H. marinum (30), H. murinum (6,10,30), H. pusillum (38) and H. spontaneum (41,42).

II. Germination regimes for non-dormant seeds

H. vulgare

S; BP: 20°C: 7d (ISTA)

S; BP: 20°C; 15°C: 7d (AOSA)

III. Unsuccessful dormancy-breaking treatments

H. jubatum

Constant temperatures: 5°C, 22°C, 35°C (36); 20°C (2)

Alternating temperatures: 5°/35°C (14h/10h) (36)

Light: continuous (2)

H. leporinum

Alternating temperatures: 40°/15°C (13h/11h) (33)

Pre-soak: 38°C, 1-10h (7)

H. pusillum

Pre-chill: 5°-10°C, 1-6w, germinate at 20°C (38)

H. spontaneum

Constant temperatures: 20°C, 30°C (41); 20°C (42)

Pre-chill: 3°C, 7d (41)

GA₃: co-applied, 0.5-25 ppm (41)

H. vulgare

Pre-soak: 20h (4,19,28); 1-5h (16)

Sodium sulphide: pre-applied, 24h, 10^-1 -10^-4 M (20)

Dimercaprol: pre-applied, 24h, 10^-3, 10^-4 M (20)

Iodoacetate: pre-applied, 24h, 10^-3, 10^-4 M (20)

Monofluoroacetate: pre-applied, 24h, 10^-2, 10^-3 M (20)

Carbon dioxide: co-applied, 10-80% (21)

Acetaldehyde: pre-applied, 24h, 10^-5 -10^-10 M (21)

Urea: pre-applied, 16h, 0.25-4% (27,28)

Oxygen: (26); 95%, 6d (20)

Ascorbic acid: pre-applied, 16h, 0.0625-0.25% (27,32)

p-Cresol: pre-applied, 16h, 0.0625-0.25% (27)

Resorcinol: pre-applied, 16h, 0.625-0.25% (27)

Protocatechuic acid: pre-applied, 16h, 0.0625-0.25% (27)

Sodium bisulphide: pre-applied, 16h, 0.0625-0.25% (27)

Sulphur dioxide: pre-applied, 16h, 0.0625-0.25% (27)

Indoleacetic acid: pre-applied, 16h, 0.25-1% (27)

Sodium tungstate: pre-applied, 16h, 0.25-1% (26)

Hydrogen sulphide: pre-applied, 16h, 31-1000 ppm (26)

Sodium hydroxide: pre-applied, 16h, 0.25-1% (26); pre-applied, 40 min, 0.5% (5)

Sodium chloride: pre-applied, 16h, 0.25-1% (26)

Trisodium phosphate: pre-applied, 16h, 0.25-1% (26)

Disodium hydrogen phosphate: pre-applied, 16h, 0.25-1% (26)

Sodium dihydrogen phosphate: pre-applied, 16h, 0.25-1% (26)

Sodium sulphate: pre-applied, 16h, 0.25-1% (26)

Sodium carbonate: pre-applied, 16h, 0.25-1% (26)

Potassium chloride: pre-applied, 24h, 10^-2 M (32)

IV. Partly-successful dormancy-breaking treatments

H. geniculatum

Constant temperatures: 5°-15°C (30)

H. glaucum

Constant temperatures: 5°-20°C (30)

Alternating temperatures: 15°/20°C (16h/8h) (30)

Pre-chill: 5°C, 12d (30)

GA₃: co-applied, 10^-4 -10^-2 M (30)

H. jubatum

Constant temperatures: 20°C (34); 10°C, 15°C (2)

Alternating temperatures: 20°/30°C (18h/6h) (34); 10°/15°C (14h/10h) (2); 20°/25°C (14h/10h) (36); 15°/20°C (14h/10h) (36)

H. leporinum

Constant temperatures: 5°-15°C (30); 8°-14°C (7)

Alternating temperatures: 20°/25°C (12h/12h) (7); 32°/18°C, 35°/13°C (12h/12h) (33)

Pre-soak: 17°C, 10h, then pre-dry, 30°C, 24h (7)

H. marinum

Warm stratification: 35°C, 31d, germinate at 15°C (30)

H. murinum

Light: (30)

H. pusillum

Alternating temperatures: 20°/30°C in dark (38)

Light: (38)

H. spontaneum

Constant temperatures: 7.5°C, 42d (42)

Removal of seed covering structures: lemma, palea and testa (41,42)

Hydrogen peroxide: co-applied, 0.5, 1% (41)

Potassium cyanide: co-applied, 5x10^-3 M (41)

Malonic acid: co-applied, 5x10^-3, 10^-2 M (41)

H. vulgare

Constant temperatures: 5°-15°C (35)

Pre-chill: 5°C, 5d (11); -1°C, 1-17d (15); -3°-(+)4°C, 3-10d (15); 12°C, 7d (18,19)

Calcium hydroxide: pre-applied, 4h, saturated solution, then sulphuric acid, pre-applied, 3.5h, 0.1% (5)

Nitric acid: pre-applied, 3-6h, 0.05-0.1% (5)

Sodium hydroxide: pre-applied, 1h, 0.5% (5)

Sulphuric acid: pre-applied, 5 min-18h, 0.01-10% (5)

Pre-dry: 35°C, 7d (8); 40°C, 5d (11,16)

Acetone: pre-applied, 5s (11)

GA₃: co-applied, 2.5x10^-5 M (12); co-applied, 5x10^-5 M (32); co-applied, 200 ppm (18); co-applied, 100-400 ppm (19); pre-applied, 16-20h, 100-200 ppm (14); 3-100 ppm (26)

Potassium nitrate: co-applied, 0.2% (19)

Antibiotics: chloramphenicol (20)

Oxygen: co-applied, 95%, 1d (20); 20 atmospheres (5)

Carbon monoxide: pre-applied, 90%, 3d (20)

Carbon dioxide: 2.5-5% (21)

Potassium cyanide: pre-applied, 24h, 10^-2 -10^-5 M (20); 8x10^-4 M (32)

Hydrogen sulphide: pre-applied, 24h, 10^-1, 10^-2 M (20); pre-applied, 16h, 0.00625-0.1% (27)

DIECA: pre-applied, 24h, 10^-3, 10^-4 M (20)

Sodium fluoride: pre-applied, 24h, 10^-2, 10^-3 M (20)

Sodium malonate: pre-applied, 10^-1, 10^-2, M (20)

Disophenol: pre-applied, 10^-2 -10^-5 M (20)

Ethanol: pre-applied, 10^-8 -10^-1 M (21)

Lactic acid: pre-applied, 24h, 10^-8 -10^-1 M (21)

Hydrogen peroxide: pre-applied, 16h, 0.25-5% (28)

Hydroquinone: pre-applied, 16h, 0.0625-0.25% (27)

Phenol: pre-applied, 16h, 0.0625-0.25% (27)

o-Cresol: pre-applied, 16h, 0.0625-0.25% (27)

m-Cresol: pre-applied, 16h, 0.0625-0.25% (27)

Catechol: pre-applied, 16h, 0.0625-0.25% (27)

Guaicol: pre-applied, 16h, 0.0625-0.25% (27)

Pyrogallol: pre-applied, 16h, 0.0625-0.25% (27)

Salicylic acid: pre-applied, 16h, 0.0625-0.25% (27)

Vanillic acid: pre-applied, 16h, 0.0625-0.25% (27)

m-Hydroxybenzoic acid: pre-applied, 16h, 0.0625-0.25% (27)

p-Hydroxybenzoic acid: pre-applied, 16h, 0.0625-0.25% (27)

8-Hydroxyquinone: pre-applied, 16h, 0.0625-0.25% (27)

Dimethylglyoxime: pre-applied, 16h, 0.0625-0.25% (27)

D-Threo-chloramphenicol: 2x10^-3 M (32)

L-Threo-chloramphenicol: 2x10^-3 M (32)

Thiourea: pre-applied, 16h, 0.25-4% (27)

Thioacetamide: pre-applied, 16h, 0.25-1% (27)

Thiosemicarbazide: pre-applied, 16h, 0.25-1% (27)

Methyl mercaptan: pre-applied, 16h, 0.0625-0.1% (27)

Ethyl mercaptan: pre-applied, 16h, 0.0625-0.1% (27)

Propyl mercaptan: pre-applied, 16h, 0.0625-0.1% (27)

Isopropyl mercaptan: pre-applied, 16h, 0.0625-0.1% (27)

Ethylene thioglycol: pre-applied, 16h, 0.0625-0.1% (27)

Ethylene dithioglycol: pre-applied, 16h, 0.0625-0.1% (27)

2-Thioglycerol: pre-applied, 16h, 0.0625-0.1% (27)

1,2-Dithioglycerol: pre-applied, 16h, 0.0625-0.1% (27)

Thioacetic acid: pre-applied, 16h, 0.0625-0.1% (27)

Thioglycollic acid: pre-applied, 16h, 0.0625-0.1% (27)

Thiosalicylic acid: pre-applied, 16h, 0.0625-0.1% (27)

Methyl thioglycollate: pre-applied, 16h, 0.0625-0.1% (27)

Ethyl thioglycollate: pre-applied, 16h, 0.0625-0.1% (27)

Propyl thioglycollate: pre-applied, 16h, 0.0625-0.1% (27)

Sodium bisulphide: pre-applied, 16h, 0.25-1% (26)

Sodium bicarbonate: pre-applied, 16h, 0.25-1% (26)

Sodium vanadate: pre-applied, 16h, 0.25-1% (26)

Potassium chlorate: pre-applied, 16h, 0.25-1% (26)

Potassium bromate: pre-applied, 16h, 0.25-1% (26)

Potassium iodate: pre-applied, 16h, 0.25-1% (26)

Kinetin: pre-applied, 16h, 6.25-25 ppm (26)

Sodium nitrite: pre-applied, 16h, 0.25-1% (26); 5x10^-1, 8x10^-3 M (32)

Sodium nitrate: pre-applied, 16h, 0.25-1% (26)

Removal of seed covering structures: (26)

Scarification: sulphuric acid, 0.5%, 40 min (5); sulphuric acid, 0.01-10%, 5 min-18h (5)

V. Successful dormancy-breaking treatments

H. geniculatum

Warm stratification: 35°C, 31d, germinate at 15°C (30)

H. glaucum

Warm stratification: 35°C, 31d, germinate at 15°C (30)

Removal of seed covering structures: lemma and palea or pierce palea, germinate at 15°C (30)

H. jubatum

Alternating temperatures: 10°/15°C (14h/10h) (36); 20°/30°C (18h/6h) (2)

H. leporinum

Constant temperatures: 17°C, 22°C (25)

Alternating temperatures: 22°/17°C, 27°/17°C (15h/9h) (25); 30°/20°C (12h/12h), 8d, then 21°C (33)

Warm stratification: 35°C, 31d, germinate at 15°C (30)

H. marinum

Constant temperatures: 5°-15°C (30)

H. murinum

Constant temperatures: 5°-15°C (29,30); 7.5°-30°C (10)

Pre-chill: 2°C, 21d (6)

Warm stratification: 35°C, 31d, germinate at 15°C (30)

H. pusillum

Alternating temperatures: 20°/30°C in light (38)

Potassium nitrate: co-applied, 0.2%, at 20°C, 20°/30°C (38)

H. spontaneum

Pre-chill: 2°C, 28d, germinate at 20°/15°C (16h/8h, 8h/16h) in light (39)

Removal of seed covering structures: lemma, palea and part of testa, germinate at 5°C (41); lemma, palea and testa, then pre-chill, 3°C, 7d (41); lemma, palea and cut endosperm, plus GA₃, co-applied, 1-25 ppm (41); lemma and palea, plus GA₃, co-applied, 25-50 ppm, then pre-chill, 3°C, 7d (41); lemma and palea, plus hydrogen peroxide, co-applied, 1% (41)

H. vulgare

Pre-chill, Pre-dry, GA₃ (ISTA)

Pre-chill, Pre-dry (AOSA)

Constant temperatures: 10°-13°C (1); 15°C (5,17,24); 10°C (8,9,12,13,15,32); 10°-12°C (16,22,23); 12°C (17); 7.5°C (42)

Pre-chill: 4°-6°C, 4d (14)

GA₃: co-applied, 500-1000 ppm (3,4); co-applied, 50-1500 ppm (11); co-applied, 0.1% (13); co-applied, 8x10^-4 M (32); pre-applied, 1-5h, 100, 1000 mg/1 in acetone (11); 16h, 0.3-10 ppm, dehusked seeds (26); pre-applied, 16h, 12.5-100 ppm with hydrogen sulphide, 500, 1000 ppm (26)

Potassium cyanide: pre-applied, 24h, 10^-2 M (20,32)

Kinetin: pre-applied, 16h, 3-25 ppm with hydrogen sulphide, 500, 1000 ppm (26)

Removal of seed covering structures: excision, piercing and/or scratching (5,8,9,12,13,16,26,28,32,40,42); deglume, plus potassium nitrate, co-applied, 0.2% (17)

Scarification: concentrated sulphuric acid, 0.5-5 min (16); sulphuric acid, 50%, 3h (28)

Oxygen: 1 atmosphere (5)

Ethanol: 0.5-1% (13); pre-applied, 30h, 3% (37)

Thiourea: pre-applied, 16h, 2% (26)

Hydrogen sulphide: pre-applied, 16h, 0.05, 0.1% (28)

Hydrogen peroxide: pre-applied, 24h, 1% (42)

Propyl mercaptan: pre-applied, 16h, 0.1% (28)

1,2-Dithioglycerol: pre-applied, 16h, 0.05% (28)

Dithiothreitol: pre-applied, 24h, 10^-1 M (32)

2-Mercaptoethanol: pre-applied, 24h, 5x10^-2 M (32)

Pre-dry: 40°C, 5d, then pre-chill, 5°C, 5d (11)

VI. Comment

Work with non-dormant aged seeds of H. vulgare has shown that between 7.5° and 12.5°C is the most suitable range of temperature for germination; at both higher and lower temperatures the germination of aged seeds is reduced (A). Fortunately this temperature range also results in the germination of virtually all dormant seeds provided the germination test period is sufficient - at least 21 days - (1,7-9,12,13,15-17,22,23,25,29, 42,A). Tests with 49 seed lots of a wide range of cultivars have confirmed that a 21 to 28 day test at 7.5°C is a suitable germination test regime for accessions of H. vulgare in gene banks and that it is unlikely that any further treatment to the seeds is required (A).

The same regime should be suitable for accessions of other Hordeum spp., but in addition removal of the lemma and palea may be required. For H. glaucum and H. geniculatum full germination was not always achieved at 10°C, and removal of the lemma and palea from ungerminated seeds which remained after 21 days in test plus a further period in test at 10°C were required (30); it is possible that this would also be required at 7.5°C.

Particular care should be taken to avoid excess moisture in seed germination tests with Hordeum spp. The germination of some seed lots will be reduced in the presence of excess moisture. The phenomenon is described as water sensitivity. See Chapter 9 for information on the correct level of moisture of germination test media.

VII. References

1. Atterberg, A. (1907). Die Nachreife des Getreides. Landwirtsch Versuchstat, 67, 129-143.

2. Banting, J.D. (1979). Germination emergence and persistence of foxtail barley. Canadian Journal of Plant Science, 59, 35-41.

3. Bekendam, J. (1975). Report of the working group on the application of gibberellic acid in routine germination testing to break dormancy of cereal seed. Seed Science and Technology, 3, 92-93.

4. Bekendam, J. and Bruinsma, J. (1965). The chemical breaking of dormancy of barley seeds. Proceedings of the International Seed Testing Association, 31, 779-787.

5. Bishop, L.R. (1944). Memorandum on barley germination. Journal of the Institute of Brewing, 50, 166-185.

6. Cocks, P.S., Boyce, K.G. and Kloot, P.M. (1976). The Hordeum murinum complex in Australia. Australian Journal of Botany, 24 651-662.

7. Cocks, P.S. and Donald, C.M. (1973). The germination and establishment of two annual pasture grasses (Hordeum leporinum Link. and Lolium rigidum Gand.). Australian Journal of Agricultural Research, 24, 1-10.

8. Corbineau, F. and Côme, D. (1980). Quelques caractéristiques de la dormance du caryopse d'orge (Hordeum vulgare L., varieté Sonja). Comptes Rendus de l'Académie des Sciences, Paris, 290, Série D, 547-550.

9. Corbineau, F. and Côme, D. (1982). Evolution de la dormance des semences de deux variétés d'orge (Hordeum vulgare L.) au cours de leur maturation et de leur conservation au sec. Comptes Rendus de l'Académie des Sciences, Paris, 294, Série III, 967-970.

10. Davidson, A.W. (1971). The ecology of Hordeum murinum L. 2. The ruderal habitat. Journal of Ecology, 59, 493-506.

11. Don, R. (1979). The use of chemicals, particularly gibberellic acid, for breaking cereal seed dormancy. Seed Science and Technology, 7, 355-367.

12. Dunwell, J.M. (1981). Dormancy and germination in embryo of Hordeum vulgare L. Effect of dissection, incubation temperature and hormone application. Annals of Botany, 48, 203-213.

13. Fischnich, O., Thielebein, M. and Grahl, A. (1961). Sekundäre Keimruhe bei getreide. Proceedings of the International Seed Testing Association, 26, 89-114.

14. Gaspar, S., Fazekas, J. and Petho, A. (1975). Effects of gibberellic acid (GA₃) and prechilling on breaking dormancy in cereals. Seed Science and Technology, 3, 555-563.

15. Grahl, A. (1970). Einfluss der Keimungstemperatur und Stratifikation auf die Keimruhe von getreide. Proceedings of the International Seed Testing Association, 35, 427-438.

16. Harrington, G.T. (1923). Forcing the germination of freshly harvested wheat and other cereals. Journal of Agricultural Research, 23, 79-100.

17. Heit, C.E. (1948). Thirty-eighth annual meeting. Report of subcommittee on dormancy of seeds. Proceedings of the Association of Official Seed Analysts, 38, 25-26.

18. Kahre, L., Kolk, H. and Fridz, T. (1965). Gibberellic acid for breaking of dormancy in cereal seed. Proceedings of the International Seed Testing Association, 30, 887-891.

19. Kåhre, L., Kolk, H. and Wiberg, H. (1962). Note on dormancy-breaking in seeds. (Cereals and timothy). Proceedings of the International Seed Testing Association, 27, 679-683.

20. Major, W. and Roberts, E.H. (1968). Dormancy in cereal seeds. I. The effects of oxygen and respiratory inhibitors. Journal of Experimental Botany, 19, 77-89.

21. Major, W. and Roberts, E.H. (1968). Dormancy in cereal seeds. II. The nature of the gaseous exchange in imbibed barley and rice seeds. Journal of Experimental Botany, 19, 90-101.

22. Munerati, M.O. (1925). Existe-t-il une aprés maturation chez les céréales récémment recoltées? Comptes Rendus de l'Académie des Sciences, Paris, 181, 1081-1083.

23. Munerati, M.O. (1926). Possibilité de déterminer l'âge des graines de blé par la temperature de leur germination. Comptes Rendus de l'Académie des Sciences, Paris, 182, 535-537.

24. Munn, M.T. (1946). Germinating freshly harvested winter barley and wheat. Proceedings of the Association of Official Seed Analysts, 36, 151-152.

25. Piggin, C.M., Hallett, M.L. and Smith, D.F. (1973). The germination response of seed of some annual pasture plants to alternating temperatures. Seed Science and Technology, 1, 739-748.

26. Pollock, J.R.A. (1959). Studies in barley and malt. XV. Growth substances and other compounds in relation to dormancy in barley. Journal of the Institute of Brewing, 65, 334-337.

27. Pollock, J.R.A. and Kirsop, B.H. (1956). Studies in barley and malt. VI. Stimulation of the germination of freshly-harvested barley. Journal of the Institute of Brewing, 62, 323-327.

28. Pollock, J.R.A., Kirsop, B.H. and Essery, R.E. (1955). Some new observations on dormancy in barley. In European Brewery Convention, Proceedings of the Congress, Baden-Baden, pp.203-211. Elsevier, Amsterdam.

29. Popay, A.I. (1975). Laboratory germination of barley grass. Proceedings of the 28th New Zealand Weed and Pest Control Conference, 7-11.

30. Popay, A.I. (1981). Germination of seeds of five annual species of barley grass. Journal of Applied Ecology, 18, 547-558.

31. Pope. M.N. and Brown, E. (1943). Induced viviparity in three varieties of barley possessing extreme dormancy. American Society of Agronomy Journal, 35, 161-163.

32. Roberts, E.H. and Smith, R.D. (1977). Dormancy and the pentose phosphate pathway. In The Physiology and Biochemistry of seed dormancy and germination (ed. A.A. Khan), pp.385-411. Elsevier/North-Holland Biomedical Press, Amsterdam.

33. Smith, D.F. (1968). The growth of barley grass (Hordeum leporinum) in annual pasture. 1. Germination and establishment in comparison with other annual pasture species. Australian Journal of Experimental Agriculture and Animal Husbandry, 8, 478-483.

34. Stevens, O.A. (1960). Weed development notes. North Dakota Agricultural Experiment Station, Fargo, North Dakota, pp.6-7.

35. Strand, E. (1964). Studies on seed dormancy in barley. Meldinger fra Norges Landbrukshogskole, 44, 1-23.

36. Ungar, I.A. (1974). The effect of salinity and temperature on seed germination and growth of Hordeum jubatum. Canadian Journal of Botany, 52, 1357-1362.

37. Deunff, Y.L. (1983). Mise en évidence de l'influence bénéfique de l'alcool éthylique en solution aqueuse sur la leveé de dormance des orges. Comptes Rendus Hebdomadaires des Séances de l'Académie des Science, Serie III, 296, 433-436.

38. Fischer, M.L., Stritzke, J.F. and Ahring, R.M. (1982). Germination and emergence of little barley (Hordeum pusillum). Weed Science, 30, 624-628.

39. Giles, B.E. and Lefkovitch, L.F. (1984). Differential germination in Hordeum spontaneum from Iran and Morocco. Zeitschrift für Pflanzenüchtung, 92, 234-238.

40. Lenoir, C., Corbineau, F. and Côme, D. (1983). Rôle des glumelles dans la dormance des semences d'orges. Physiologie Végétale, 21, 633-643. (From Seed Abstracts, 1984, 7, 1702.)

41. Ogawara, K. and Hayashi, J. (1964). Dormancy studies in Hordeum spontaneum seeds. Berichte d. Ohara Instituts Landwirtschaftliche, Biologia Okayama Universitat, 12, 159-188.

42. Urion, E. and Chapon, L. (1955). Contribution à l'étude de la dormance de l'orge. In European Brewery Convention, Proceedings of the Congress, Baden-Baden, pp. 172-202. Elsevier, Amsterdam.

LOLIUM

L. multiflorum Lam. (L. italicum A. Br.)	Italian ryegrass
L. multiflorum L. x L. perenne L. [L. x hybridum Hausskn.]	short rotation ryegrass
L. perenne L.	perennial ryegrass, English ryegrass
L. temulentum L. [L. persicum Boiss & Hoh.; L. rigidum Gaud.]	darnel, bearded ryegrass, persian ryegrass, annual ryegrass

I. Evidence of dormancy

Freshly harvested seeds of Lolium spp. show considerable dormancy (1-4,8,10,16-19,23-26). This causes substantial problems in seed testing (1,3,8,23,25).

II. Germination regimes for non-dormant seeds

L. multiflorum

TP: 15°/25°C; 20°/30°C (16h/8h); 20°C: 14d (ISTA)

TP: 15°/25°C (16h/8h): 14d (AOSA)

Constant temperatures: 20°C (14); 14°-25°C (22); 10°-25°C (24); 15°-30°C (12)

Alternating temperatures: (12); 20°/25°C in light (14,15); 15°/25°C (15); 5°/10°C, 5°/15°C, 10°/15°C, 10°/30°C, 15°/30°C, 15°/40°C (16h/8h) (24); 25°/18°C (day/night) in light (13)

L. multiflorum x L. perenne

TP: 15°/25°C; 20°/30°C (16h/8h); 20°C: 14d (ISTA)

L. perenne

TP: 15°/25°C; 20°/30°C; (16h/8h); 20°C: 14d (ISTA)

TP: 15°/25°C (16h/8h): 14d (AOSA)

L. temulentum

Constant temperatures: 10°-15°C (4,6); 17°-22°C (21); 12°C in dark (11); 24°C in light (11)

III. Unsuccessful dormancy-breaking treatments

L. multiflorum

Constant temperatures: 25°C, 30°C (26)

GA₃: co-applied, 100 ppm (19); pre-applied, 12-18h, 50-100 ppm (20)

L. perenne

Potassium cyanide: pre-applied, 24h, 10^-2-10^-4 M (18)

Hydrogen sulphide: pre-applied, 24h, 10^-1, 10^-2 M (18)

Sodium sulphide: pre-applied, 24h, 10^-1-10^-4 M (18)

Ammonium hydroxide: pre-applied, 24h, 10^-2, 10^-3 M (18)

GA₃: co-applied, 100 ppm (19)

L. temulentum

Pre-soak: 38°C, 1-10h (6)

IV. Partly-successful dormancy-breaking treatments

L. multiflorum

Alternating temperatures: 10°/30°C (16h/8h) (1,2,8); 20°/30°C (16h/8h) (1,2,9); 15°/30°C in light (19); 5°/15°C, 5°/20°C, 5°/25°C, 10°/15°C, 15°/25°C (16h/8h) (24)

Pre-chill: 5°C, 5d (3,8,19,23-26); 5°C, 5d, then again, 5°C, 2-3d, after 14d test (3,23); 5°C, 5d, plus potassium nitrate, co-applied, 0.2%, at 20°/30°C, 10°/30°C (16h/8h) (8); 5°C, 5d, plus potassium nitrate, co-applied, 0.2% at 15°/25°C (16h/8h) in light (8,24,25)

Light: (1,2,3,19)

Potassium nitrate: co-applied, 0.2% (1-3,7-9,19,23-26)

Thiourea: co-applied, 0.2% (19)

Pre-soak: 22°C, 17h, then pre-dry, 15°C, 24h (5)

Pre-dry: 35°C, 5d, plus potassium nitrate, co-applied, 0.2%, at 15°/25°C (16h/8h) in light (8)

L. perenne

Alternating temperatures: 20°/30°C (16h/8h) (9); 15°/30°C in light (19); 25°/18°C, 30°/18°C, 18°/25°C (day/night) (13)

Pre-chill: 5°C, 5d (19); 5°C, 5d, plus potassium nitrate, co-applied, 0.2% (25)

Pre-soak: 22°C, 17h, then pre-dry, 15°C, 24h (5)

Light: (19); 5 min (27)

Potassium nitrate: co-applied, 0.2% (19,27)

Potassium cyanide: pre-applied, 24h, 10^-5 M (18)

Thiourea: co-applied, 0.2% (19)

L. temulentum

Alternating temperatures: 24°/12°C (12h/12h) (11); 10°/30°C (16h/8h) (4)

Light: 8h/d (4); 12h/d (11)

Pre-soak: 10h, then pre-dry, 30°C, 24h (6)

V. Successful dormancy-breaking treatments

L. multiflorum

Pre-chill, Potassium nitrate (ISTA)

Light, Potassium nitrate, Pre-chill, further Pre-chill (AOSA)

Alternating temperatures: 15°/20°C, 15°/25°C, 20°/25°C, 20°/30°C, 25°/30°C (16.5h/7.5h) (12); 20°/30°C, 20°/25°C (16h/8h) in light (14); 10°/30°C (16h/8h) (17); 5°/10°C (16h/8h) (24); 18°/36°C, 10°/36°C (16h/8h) (10); 20°/30°C (16h/8h), 14d, then potassium nitrate, co-applied, 0.2%, at 20°/30°C (16h/8h), 5d (9)

Pre-chill: 5°C, 4d (14); plus further pre-chill (16); 5°C, 5d, plus potassium nitrate, co-applied, 0.2%, at 15°/25°C (16h/8h) in light (26); 5°C, 5d, plus potassium nitrate, co-applied, 0.2%, at 15°/25°C, 10°/30°C (16h/8h) in light, 14d, then further pre-chill, 5°C, 2-3d (8)

Pre-dry: test for 14d, then pre-chill (16); 35°C, 5d, then potassium nitrate, co-applied, 0.2%, at 15°/25°C (16h/8h) in light, 14d, then pre-chill, 5°C, 2-3d (8)

Potassium nitrate: co-applied, 0.2%, at 10°/30°C (16h/8h) in light, 100 fc (2); co-applied, 0.2%, at 15°/25°C (16h/8h) in light (7)

L. multiflorum x L. perenne

Pre-chill, Potassium nitrate (ISTA)

L. perenne

Pre-chill, Potassium nitrate (ISTA)

Light, Potassium nitrate, Pre-chill, further Pre-chill (AOSA)

Alternating temperatures: 15°/20°C, 15°/25°C, 20°/25°C, 20°/30°C, 25°/30°C (16.5h/7.5h) (12); 10°/20°C (15h/9h) (27); 18°/36°C, 10°/36°C (16h/8h) (10); 20°/30°C (16h/8h), 10d, then potassium nitrate, co-applied, 0.2% at 20°/30°C (16h/8h), 5d (9); 5°C, 5d, plus potassium nitrate, co-applied, 0.2%, at 15°/25°C (16h/8h) in light (25,26)

Potassium nitrate: co-applied, 0.2%, at 20°C, 10°/20°C (15h/9h) in light (27)

L. temulentum

Constant temperatures: 12°C (11)

Alternating temperatures: 24°/12°C (12h/12h) (11); 10°/30°C (16h/8h) in light (4); 32°/22°C (15h/9h) (21)

VI. Comment

The earlier ISTA prescription (1976 rules) for germination tests with dormant seeds (light, pre-chill, potassium nitrate, and an alternating temperature of 10°/30°C) is not satisfactory for freshly harvested seeds (1,3,8,23). The AOSA prescription (potassium nitrate, pre-chill, and an alternating temperature of 15°/25°C with a further pre-chill if seeds remain ungerminated) appears to be more successful provided the change of temperature in the alternating temperature regime is rapid (8). However, rapid changes are rarely achieved in alternating temperature incubators. A Copenhagen tank where the water is completely changed between cycles would give a rapid temperature change, as would manual movement of germination tests twice daily between two constant temperature incubators.

There is some evidence that 15°/25°C may not be the most suitable alternating temperature regime (1,24). An alternation of 15°/25°C (16h/8h) has been reported to give higher germination than 10°/30°C (16h/8h) (3,8) which in turn is better than 20°/30°C (16h/8h) (17). However, 5°/10°C (16h/8h) was superior to all the above (24). Consequently it is suggested that this latter regime be applied, but with an extended test period compared to ISTA/AOSA prescriptions. If this does not completely break dormancy potassium nitrate could be co-applied and/or the seeds pre-chilled for 5 days. If it is not possible to provide an alternating temperature regime of 5°/10°C the following alternating temperatures have also been reported to give high germination: 5°/15°C, 5°/20°C, 5°/25°C, 10°/15°C (16h/8h) (24).

VII. References

1. Andersen, A.M. (1947). The effect of alternating temperatures, light intensities, and moistening agents of the substratum on the germination of freshly harvested seed of Oregon-grown rye-grass (Lolium spp.). Proceedings of the Association of Official Seed Analysts, 37, 152-161.

2. Andersen, A.M. (1954). Some factors affecting the germination of 1- and 2-year old ryegrass (Lolium) seed. Proceedings of the International Seed Testing Association, 19, 5-13.

3. Anonymous (1960). Dormancy in common ryegrass. Newsletter of the Association of Official Seed Analysts, 34, 31-33.

4. Banting, J.D. and Gebhardt, J.P. (1979). Germination, after-ripening, emergence, persistence and control of persian darnel. Canadian Journal of Plant Science, 59, 1037-1045.

5. Chippindale, H.G. (1933). The effect of soaking in water on the "seeds" of some gramineae. Annals of Botany, 21, 225-232.

6. Cocks, P.S. and Donald, C.M. (1973). The germination and establishment of two annual pasture grasses (Hordeum leporinium Link. and Lolium rigidum Gaud.). Australian Journal of Agricultural Research, 24, 1-10.

7. Colbry, V.L. (1956). Report of the subcommittee on germination. Proceedings of the Association of Official Seed Analysts, 46, 12-13.

8. Colbry, V.L., Wiseman, E.F. and Justice, O.L. (1961). Germination of freshly-harvested ryegrass seed grown in 1960. Proceedings of the Association of Official Seed Analysts, 51, 131-138.

9. Crosier, W. and Cullinan, B. (1941). Some observations in the germination of grass seeds. Proceedings of the Association of Official Seed Analysts, 33, 69-74.

10. Gadd, V. (1939). Uber Methoden zur Hebung mangelnder Keimreife in der Samenkontrollarbeit. Proceedings of the International Seed Testing Association, 11, 96-118.

11. Gramshaw, D. (1972). Germination of annual ryegrass seeds (Lolium rigidum Gaud.) as influenced by temperature, light, storage environment and age. Australian Journal of Agricultural Research, 23, 779-787.

12. Harrington, G.T. (1923). Use of alternating temperatures in the germination of seeds. Journal of Agricultural Research, 23, 295-332.

13. Harrison, C.S. (1954). The technique of ultra-violet testing in New Zealand. Proceedings of the International Seed Testing Association, 19, 44-49.

14. Johnston, M.E.H. and Miller, J.G. (1962). Investigation into germination techniques for ryegrass, Lolium spp. Proceedings of the International Seed Testing Association, 27, 345-356.

15. Johnston, M.E.H. and Tattersfield, J.G. (1970). Comparison of germination temperature treatments for ryegrass, Lolium spp. Proceedings of the International Seed Testing Association, 35, 325-340.

16. Justice, O.L. (1962). Discussion. Proceedings of the International Seed Testing Association, 27, 764.

17. Kahre, L. (1962). Discussion. Proceedings of the International Seed Testing Association, 27, 765.

18. Major, W. and Roberts, E.H. (1968). Dormancy in cereal seeds. I. The effects of oxygen and respiratory inhibitors. Journal of Experimental Botany, 19, 77-89.

19. Nakamura, S. (1962). Germination of grass seeds. Proceedings of the International Seed Testing Association, 27, 710-729.

20. Peacock, C.H., Dudeck, A.E. and Green, R.L. (1980). Effects of seed soaking and Gibberellic acid on the germination and establishment of annual ryegrass and Kentucky 31 tall fescue grass. Agronomy Abstracts, 72nd annual meeting American Society of Agronomy, 119.

21. Piggin, C. McE., Hallett, M.L. and Smith, D.F. (1973). The germination response of seed of some annual pasture plants to alternating temperatures. Seed Science and Technology, 1, 739-747.

22. Simon, J.C. (1981). Contribution à l'étude écophysiologique de la phase semis-levée du ray-grass d'Italie (Lolium multiforum Lam.) I. Etude en conditions controleés de l'influence du facteur thermique. Agronomie, 1, 339-344.

23. Weisner, M. and Kanipe, L.A. (1951). Delayed germination of Lolium multiflorum - common ryegrass. Proceedings of the Association of Official Seed Analysts, 41, 86-88.

24. Young, J.A., Evans, R.A. and Kay, B.L. (1975). Germination of Italian ryegrass seeds. Agronomy Journal, 67, 386-389.

25. Jensen, L.A. and Pierpoint, M. (1961). Survey of post-harvest dormancy in Oregon rye-grass samples. Proceedings of the Association of Official Seed Analysts, 51, 178-183.

26. Wiesner, L.E. and Grabe, D.F. (1972). Effects of temperature pre-conditioning and cultivar on ryegrass (Lolium spp.) seed dormancy. Crop Science, 12, 760-764.

27. Williams, E.D. (1983). Effects of temperature, light, nitrate and pre-chilling on seed germination of grassland plants. Annals of Applied Biology, 103, 161-172.

ORYZA

O. glaberrima Steud.	African rice
O. sativa L.	rice, red rice

I. Evidence of dormancy

O. glaberrima cultivars are generally the most dormant, followed by the indica, javanica and japonica cultivars of O. sativa, the latter being the least dormant (4). Seeds of wild rice (O. sativa var spontanea) show a similar level of dormancy to O. glaberrima (39).

II. Germination regimes for non-dormant seeds

O. sativa

BP; TP; S: 20°/30°C (16h/8h); 25°C: 14d (ISTA)

BP; TP; S: 20°/30°C (16h/8h): 14d (AOSA)

Constant temperatures: 28°-36°C (2); 30°-35°C (22); 27°-36°C (11-13); 32°C (5); 30°C (17,27,39)

III. Unsuccessful dormancy-breaking treatments

O. glaberrima

Removal of seed covering structures: (24); excise embryos, germinate at 30°C, dark (39)

Potassium cyanide: pre-applied, 24h, 10^-3 M (10)

O. sativa

Alternating temperatures: 20°/26°C (15); 20°/30°C (26)

Removal of seed covering structures: dehull, germinate at 30°C, dark (39); excise embryos, germinate at 30°C, dark (39)

Potassium chlorate: pre-applied, 24h, 10^-1 -10^-3 M (34)

Potassium dichromate: pre-applied, 24h, 10^-1 -10^-3 M (34)

Calcium hypochlorite: pre-applied, 24h, 10^-1 -10^-3 M (34)

Potassium permanganate: pre-applied, 24h, 10^-1 -10^-3 M (34)

Dimercaprol: pre-applied, 24h, 10^-3 -10^-4 M (34)

2,2-Dipyridyl: pre-applied, 24h, 10^-3 -10^-4 M (34)

1,10 Phenanthroline: pre-applied, 24h, 10^-3 -10^-4 M (34)

8-Hydroxyquinoline: pre-applied, 24h, 10^-3 -10^-4 M (34)

Disodium edetate: pre-applied, 24h, 10^-3 -10^-4 M (34)

Adenine: co-applied, 10^-7 -10^-2 M, at 30°C, dark, dehulled seeds (6)

Sodium hydroxide: pre-applied, 10,20,30 min, 0.1 N, germinate at 30°C, dark, dehulled seeds (39)

Sodium nitrate: co-applied, 10^-2 M, at 30°C, light or dark, dehulled seeds (7)

Sodium diethyldithiocarbamate: pre-applied, 24h, 10^-3 -10^-4 M (34)

Sodium malonate: pre-applied, 24h, 10^-3 -10^-4 M (34)

Sodium monofluoroacetate: pre-applied, 24h, 10^-2 M (34)

Sodium iodoacetate: pre-applied, 24h, 10^-3 -10^-4 M (33)

Sodium fluoride: pre-applied, 24h, 10^-2 -10^-3 M (34)

Sodium arsenite: pre-applied, 24h, 10^-2 -10^-3 M (34)

Sodium arsenate: pre-applied, 24h, 10^-2 -10^-3 M (34)

2,4 Dinitrophenol: pre-applied, 24h, 10^-3 -10^-6 M (34)

Sodium p-chloromercuribenzoate: pre-applied, 24h, 10^-3 -10^-4 M (34)

Sodium malate: pre-applied, 24h, 10^-2, 10^-1 M (33)

Potassium sodium tartarate: pre-applied, 24h, 10^-2, 10^-1 M (33)

Sodium formate: pre-applied, 24h, 10^-2, 10^-1 M (33)

Sodium acetate: pre-applied, 24h, 10^-2, 10^-1 M (33)

Sodium lactate: pre-applied, 24h, 10^-2, 10^-1 M (33)

Sodium oxalate: pre-applied, 24h, 10^-2, 10^-1 M (33)

Sodium pyruvate: pre-applied, 24h, 10^-2, 10^-1 M (33)

Sodium citrate: pre-applied, 24h, 10^-2, 10^-1 M (33)

Sodium fumarate: pre-applied, 24h, 10^-2, 10^-1 M (33)

Sodium succinate: pre-applied, 24h, 10^-2, 10^-1 M (33)

Ammonium sulphate: pre-applied, 12-36h, 10^-2 M (32)

Ammonium chloride: co-applied, 10^-2 M, at 30°C in light or dark, dehulled seeds (7)

Urea: pre-applied, 24h, 10^-2 -10^-4 M (32)

Oxidised glutathione: pre-applied, 24h, 10^-8 -10^-4 M (33)

Reduced glutathione: pre-applied, 24h, 10^-4 -10^-2 M (33)

L-Cysteine: pre-applied, 24h, 10^-4 -10^-2 M (33)

Sodium thioglycollate: pre-applied, 24h, 10^-4 -10^-2 M (33)

L-Cystine: pre-applied, 24h, 10^-4, 10^-3 M (33)

Sodium hypochlorite: pre-applied, 12h, 0.05% (23)

3-Indoleacetic acid: pre-applied, 24h, 10^-5 -10^-3 M (33)

Light: (9); fluorescent, continuous, 6x10^-5 mol m^-2 s^-1, dehulled seeds (6)

Sulphuric acid: pre-applied, 10,20,30 min, 0.1 N, germinate at 30°C, dark, dehulled seeds (39)

IV. Partly-successful dormancy-breaking treatments

O. glaberrima

Nitric acid: pre-applied, 12h, 0.7 M, germinate at 20°/30°C (16h/8h) (10); pre-applied, 24h, 0.4, 0.5 M, germinate at 20°/30°C (16h/8h) (10); pre-applied, 24h, 0.1, 0.2 M, then hydrogen peroxide, pre-applied, 24h, 0.25-1 M, germinate at 20°/30°C or 34°/11°C (16h/8h) (10); pre-applied, 24h, 0.1 M, then hydrogen peroxide, pre-applied, 24h, 0.25 M, with or without thiourea, co-applied, 2x10^-2, 5x10^-2 M, or sodium azide, co-applied, 10^-4, 10^-3 M, or 2-mercaptoethanol, co-applied, 10^-2, 2.5x10^-2 M, germinate at 34°/11°C (16h/8h) (10)

Hydrochloric acid: pre-applied, 10-15 min, 10-14%, germinate at 30°C, dark, dehulled seeds (39)

Sulphuric acid: pre-applied, 15 min, 15-35%, germinate at 30°C, dark, dehulled seeds (39)

GA₃: pre-applied, 24h, 10^-4 -10^-2 M, germinate at 20°/30°C (16h/8h) (10)

GA_4/7: pre-applied, 24h, 10^-4 -10^-2 M, germinate at 20°/30°C (16h/8h) (10)

O. sativa

Constant temperatures: 25°C (37); 27°C (31,35); 30°C (17,18,26,37); 31°C (13); 32°C (15)

Alternating temperatures: 30°/15°C (16h/8h) (26); 20°/32°C (15); 20°/30°C (16h/8h) (37)

Warm stratification: 40°C, 50°C (15)

Pre-dry: 47°C, 7d (3)

Removal of seed covering structures: dehull (9,20,26,28,30,40); pericarp and seed coat (38); cut in half (9); dehull, cut in half (9,30); clip one third of hull (16); dehull, germinate at 30°C, dark (8)

Oxygen: 100% (14,15,36)

Carbon monoxide: 90% (34)

Carbon dioxide: pre-applied, 30°C, 2-5d, 20-100% (40)

Thiourea: pre-applied, 2h, 0.5% (25); co-applied, 0.2% (26,40); co-applied, 10^-2 M (33)

Potassium cyanide: pre-applied, 24h, 10^-3 M (34)

Sodium sulphide: pre-applied, 24h, 10^-2-10^-4 M (34)

Hydrogen sulphide: pre-applied, 24h, 10^-1-10^-3 M (34)

Hydroxylamine hydrochloride: pre-applied, 24h, 10^-2-10^-3 M (34)

Sodium azide: pre-applied, 10^-3 M (34)

Methylene blue: pre-applied, 10^-3 M (34)

Sodium hypochlorite: pre-applied, 24-72h, 20°-40°C, 0.25% (9)

Pre-soak: 45h, 3°C (31); 24h, 23°C (32); 24-72h, 20°-40°C (9)

Ethanol: 0.5-2.0% (16)

Nitric acid: pre-applied, 16-24h, 10^-1 N (19); pre-applied, 12h, 10^-1 N (21); pre-applied, 12-48h, 10^-2 N (32)

Potassium nitrate: pre-applied, 24h, 10^-2 M (32)

Sodium nitrate: pre-applied, 12-36h, 10^-2 M (32); co-applied, 10^-2 M (32)

Sodium nitrite: pre-applied, 12-36h, 10^-2 M (32); co-applied, 10^-2 M, pH3, at 30°C in light or dark, dehulled seeds (7)

Hydrogen peroxide: pre-applied, 24h, 1 M (34); 1% (41)

Sulphuric acid: pre-applied, 12-48h, 10^-2 N (32); pre-applied, 4h, 10^-1 N (36); pre-applied, 3h, 10^-1 N (25)

Hydrochloric acid: pre-applied, 12-48h, 10^-2 N (32)

GA₃: co-applied, 100ppm (26); pre-applied, 24h, 10^-3 M (33)

Kinetin: pre-applied, 24h, 10^-3 M (33); co-applied, 5x10^-4, 10^-3 M, at 30°C, dark, dehulled seeds (6)

Benzyladenine: co-applied, 5x10^-4, 10^-3 M, at 30°C, dark, dehulled seeds (6)

Isopentenyl adenine: co-applied, 10^-7-10^-2 M, at 30°C, dark, dehulled seeds (6)

Zeatin: co-applied, 10^-3 M, at 30°C, dark, dehulled seeds (6)

Light: (31)

V. Successful dormancy-breaking treatments

O. glaberrima

Alternating temperatures: 34°/11°C (16h/8h) with nitric acid, pre-applied, 24h, 10^-1 M, then hydrogen peroxide, pre-applied, 24h, 0.25 M, plus 2-mercaptoethanol, co-applied, 10^-2 M (10)

Removal of seed covering structures: excise embryos, plus sucrose, co-applied, 2%, at 30°C, dark (39)

After-ripening: 30°C, 11-12% moisture content, 80d, germinate at 20°/30°C (16h/8h) (10)

O. sativa

Pre-soak in water or Potassium nitrate, 24h, Pre-dry (ISTA)

Flood test (AOSA)

Alternating temperatures: 34°/11°C (16h/8h), with nitric acid, pre-applied, 24h, 10^-1 M, then hydrogen peroxide, pre-applied, 24h, 0.25 M, plus 2-mercaptoethanol, co-applied, 10^-2 M (10)

Removal of seed covering structures: dehull, plus GA₃, co-applied, 100ppm (26); dehull, plus thiourea, co-applied, 0.2% (26); prick near embryo (20); lemma (17); cut endosperm (28); kernels (36); puncture glumes (36); dehull, scarify pericarp and testa (30); dehull, nick pericarp (9); hull, pericarp and testa (16); excise embryos (8); excise embryos, plus sucrose, co-applied, 2%, at 30°C, dark (39)

Ethylene chlorohydrin: pre-applied, 24-72h, 0.1%, germinate at 20°-30°C (9)

Nitric acid: pre-applied, 23h, 10^-1 N (1)

Hydrochloric acid: pre-applied, 15 min, 14%, germinate at 30°C, dark, dehulled seeds (39); pre-applied, 15 min, 14%, after 96h imbibition, germinate at 30°C, dark, dehulled seeds (39)

Alcohol: pre-applied, 10 min, 80%, germinate at 30°C, dark, dehulled seeds (39)

VI. Comment

Seed dormancy in O. sativa is a considerable problem in commercial seed testing (e.g. 9). In gene banks the problem is substantially greater: first accessions of O. sativa are likely, overall, to show considerably deeper dormancy than is the case for seed lots in commercial testing; second accessions of the considerably more dormant O. glaberrima will have to be germinated. In view of this and the importance of rice as a staple, a separate study with practical recommendations for those working in gene banks has been published elsewhere (10) - to which the reader is referred for detailed information.

The details of the AOSA flood test for rice are: plant the seeds in moist sand and test for 7 days; then add water to a depth of 7 mm above the sand and continue the test for a further 7 days. The dormancy-breaking procedure previously recommended by ISTA for O. sativa (pre-soak the seeds for 24 to 48 hours in water at 40°C) is questionable. Although this or similar procedures can be promotory in some cases (9,21,41), in other cases promotion may be small or non-existent (10,31), or the pre-treatment may damage the seeds and reduce germination (10). Moreover, in deeply dormant cultivars of O. glaberrima no promotory effect has been observed (A). The pre-soak treatment in hot water is no longer recommended by ISTA and should not be used.

Although dehusking can be successful with seeds of O. sativa - though apparently less successful for O. glaberrima (24) - particularly when combined with additional dormancy-breaking agents it is not a particulary useful treatment since aside from being extremely time-consuming there is a possibility of damage to the embryo resulting from the treatment and a tendency for the dehusked grains to succumb to bacterial and fungal attack (30).

A number of techniques have been developed for use in rice-breeding programmes (3) of which the most relevant is after-ripening. The treatment, 47°C for 7 days for seeds with less than 11% moisture content (3), is widely used (a similar treatment - pre-dry at 50°C - is now recommended as a dormancy-breaking procedure by the ISTA). It should not be applied to the entire accession, but its use on sub-samples can be sanctioned for moderately dormant lots of O. sativa provided these are of high quality. However, this procedure is not feasible for O. glaberrima - since they require 30-60 day treatments (35) - and probably not for the more dormant O. sativa accessions. Another dormancy-breaking agent best avoided by gene banks is the use of gibberellins since their use can affect the growth and development of subsequent seedlings (29).

To avoid these problems and to enable gene bank staff to be able to germinate dormant seeds of rice required the development of procedures requiring five separate dormancy-breaking agents: viz, alternating temperature, hydrogen ions, nitrate ions, hydrogen peroxide and 2-mercaptoethanol (10). It was not possible to develop a single satisfactory procedure for seeds of all taxonomic groups (10). Nevertheless the procedures developed are easy to follow.

For japonica cultivars of O. sativa (which usually show only slight dormancy) a diurnal temperature alternation of 30°/20°C (16h/8h) is satisfactory. (Note that the periods spent at each temperature are the reverse of the ISTA/AOSA prescriptions.) Alternatively a regime of 34°/11°C (16h/8h) can be used. For O. glaberrima and indica and javanica cultivars of O. sativa the alternating temperature regime 34°/11°C (16h/8h) is best. In addition seeds of O. glaberrima and probably the more dormant indica and spontanea accessions of O. sativa require a pre-treatment in 0.1 M nitric acid for 24 hours followed by a further 24 hours pre-treatment in 0.25 M hydrogen peroxide with subsequent germination on filter paper moistened with 0.01 M 2-mercaptoethanol at 34°/11°C (16h/8h). Should operational constraints in the running of the laboratory preclude separate dormancy-breaking treatments according to taxonomic classification, then all rice seed accessions should be germinated according to this last method for the most dormant seeds. For most O. sativa accessions a 14 day test period is sufficient. However, for O. glaberrima and the most dormant O. sativa accessions the germination test period may have to be extended to 42 days, or more.

VII. References

1. Agrawal, P.K. and Nanda, J.S. (1969). A note on dormancy in rice. Riso, 18, 325-326.

2. Akemine, M. (1914). Zur Kenntnis der Keimungsphysiologie von Oryza sativa (Reis). Fühlings Landwirtschaftlich Zeitung, 63, 78-93. (Cited and re-analysed by Livingston and Haasis, 1933.)

3. Carpenter, A.J. and Roberts, E.H. (1962). Some useful techniques in speeding up rice breeding programmes. Empire Journal of Experimental Agriculture, 30, 127-131.

4. Chang, T.T. (1976). The rice cultures. Philosophical Transactions of the Royal Society of London, Series B, 275, 143-157.

5. Chaudhary, T.N. and Ghildyal, B.P. (1969). Germination response of rice seeds to constant and alternating temperatures. Agronomy Journal, 61, 328-330.

6. Cohn, M.A. and Butera, D.L. (1982). Seed dormancy in red rice (Oryza sativa). II. Response to cytokinins. Weed Science, 30, 200-205.

7. Cohn, M.A., Butera, D.L. and Hughes, J.A. (1983). Seed dormancy in red rice. III. Response to nitrite, nitrate, and ammonium ions. Plant Physiology, 73, 381-384.

8. Cohn, M.A. and Hughes, J.A. (1981). Seed dormancy in red rice (Oryza sativa). I. Effect of temperature on dry-afterripening. Weed Science, 29, 402-404.

9. Delouche, J.C. and Nguyen, N.T. (1964). Methods for overcoming seed dormancy in rice. Proceedings of the Association of Official Seed Analysts, 54, 41-49.

10. Ellis, R.H., Hong, T.D. and Roberts, E.H. (1983). Procedures for the safe removal of dormancy from, rice seed. Seed Science and Technology, 11, 77-112.

11. Hall, V.L. (1966). Temperature and the germinating rice seed. I. Minimum to maximum temperature for growth in four days. Rice Journal, 69, 40-42.

12. Hall, V.L. (1966). Temperature and the germinating rice seed. II. Effect of temperature on germination and eight days growth of aerated seed. Rice Journal, 69, 22-23.

13. Hall, V.L. (1966). Temperature and the germinating rice seed. III. Effect of temperature on germination and eight days growth of submerged seeds. Rice Journal, 69, 14-15.

14. Hayashi, M. (1980). [Studies on dormancy and germination of rice seed. IX. The effects of oxygen and moisture upon the release of the rice seed dormancy and upon the inactivation of inhibitors in the dormant seed.] Bulletin of the Faculty of Agriculture, Kagoshima University, 30, 1-9.

15. Hayashi, M. and Morifuji, N. (1972). [Studies on the dormancy and germination of rice seed. I. The influences of temperatures and gaseous conditions on dormancy and germination in rice seeds.] Japanese Journal of Tropical Agriculture, 16, 115-120.

16. Ikeda, M. (1963). [Studies on the viviparous germination of rice seed.] Bulletin of the Faculty of Agriculture, Kagoshima University, 13, 89-115.

17. Ikehashi, H. (1973). [Studies on the environmental and varietal differences of germination habits in rice seeds with special reference to plant breeding.] Journal of the Central Agricultural Experiment Station, Konosu, 19, 1-60.

18. Ikehashi, H. (1975). Dormancy formation and subsequent changes of germination habits in rice seeds. Japanese Agricultural Research Quarterly, 9, 8-12.

19. International Rice Research Institute (1968). Seed dormancy. IRRI Reporter, 4, 1-4.

20. International Rice Research Institute (1974). Annual Report for 1973, pp. 9-11. International Rice Research Institute, Los Baños, The Philippines.

21. Jalote, S.R. and Vaish, C.P. (1976). Dormancy behaviour of paddy varieties in U.P. Seed Research, 4, 187-190.

22. Livingston, B.E. and Haasis, F.W. (1933). Relations of time and maintained temperature to germination percentage for a lot of rice seed. American Journal of Botany, 20, 596-615.

23. Mikkelsen, D.S. and Sinah, M.N. (1961). Germination inhibition in Oryza sativa and control by preplanting soaking treatments. Crop Science, 1, 332-335.

24. Misra, P.K. and Misro, B. (1970). Seed dormancy in the African cultivated rice (Oryza glaberrima Steud.). Indian Journal of Agricultural Science, 40, 13-16.

25. Murty, K.S. and Raghavaiah, P. (1966). Observations on dormancy in rice seed. Current Science, 35, 548.

26. Nakamura, S. (1963). Short communication on dormancy of rice seed. Proceedings of the International Seed Testing Association, 28, 57-59.

27. Nishiyama, I. (1978). Further evidence for the break on the Arrhenius plot of germination activity in rice seeds. Japanese Journal of Crop Science, 47, 557-562.

28. Oka, H.I. and Tsai, K.H. (1955). [Dormancy and longevity of rice seed with regard to their variations among varieties.] Japanese Journal of Breeding, 5, 22-26.

29. Roberts, E.H. (1959). Geotropic and morphological alterations in rice seedlings caused by plant growth regulators. Nature, 183, 1197-1198.

30. Roberts, E.H. (1961). Dormancy in rice seed. II. The influence of covering structures. Journal of Experimental Botany, 12, 430-445.

31. Roberts, E.H. (1962). Dormancy in rice seed. III. The influence of temperature, moisture and gaseous environment. Journal of Experimental Botany, 12, 75-94.

32. Roberts, E.H. (1963). The effects of inorganic ions on dormancy in rice seed. Physiologia Plantarum, 16, 732-744.

33. Roberts, E.H. (1963). The effects of some organic growth substances and organic nutrients on dormancy in rice seed. Physiologia Plantarum, 16, 745-755.

34. Roberts, E.H. (1964). The distribution of oxidation-reduction enzymes and the effects of respiratory inhibitors and oxidising agents on dormancy in rice seed. Physiologia Plantarum, 17, 14-29.

35. Roberts, E.H. (1965). Dormancy in rice seed. IV. Varietal responses to storage and germination temperatures. Journal of Experimental Botany, 16, 341-349.

36. Sikder, H.P. (1967). Dormancy of paddy seeds in relation to different seed treatments. Experimental Agriculture, 3, 249-255.

37. Singh, P.V., Singh, M.B. and Khanna, A.N. (1973). Note on the temperature requirements of germinating rice seeds under controlled conditions. Indian Journal of Agricultural Science, 43, 426-427.

38. Sugawara, T. (1973). On the dormancy of seeds in Oryza glaberrima. Bulletin of the College of Agriculture, Utsunomiya University, Japan, 8, 43-49.

39. Takahashi, N. (1963). Studies on the dormancy of wild rice seeds. Science Reports, Research Institutes, Tohoku University, Series D, 14, 75-85.

40. Tseng, S. (1964). Breaking dormancy of rice seed with carbon dioxide. Proceedings of the International Seed Testing Association, 29, 445-450.

41. Yasue, T. (1973). [Effect of moisture content of seeds and soaking in water on breaking dormancy in indica rice.] Research Bulletin of the Faculty of Agriculture, Gifu University, 34, 1-10.

ORYZOPSIS

O. hymenoides (Roem. & Schult.) Ricker	Indian ricegrass
O. miliacea (L.) Ascherson & Schweinfurth	smilo ricegrass, smilograss

I. Evidence of dormancy

O. hymenoides seeds show very deep dormancy at harvest (1,2,7,11,13), and seeds stored for six (11) or nine (19) years can remain dormant. Dormancy in seeds of O. miliacea, however, tends not to be so pronounced (3,5).

II. Germination regimes for non-dormant seeds

O. hymenoides

TP: 15°C: 42d (AOSA)

S: 5°/15°C; 15°/25°C (16h/8h); 15°C: 28d (AOSA)

O. miliacea

S: 15°C: 42d (ISTA)

TP: 20°/30°C (16h/8h): 42d (AOSA)

III. Unsuccessful dormancy-breaking treatments

O. hymenoides

Alternating temperatures: 15°/15°-35°C, 20°/25°-30°C, 20°/30°C (15h/9h) (1); -20°/43°C (freeze/thaw) (7)

Pre-chill: -18°C, in sand (12)

Radio frequency: 41 MHz, 2 Kv/cm, 8-36s (1)

Potassium nitrate: pre-applied, 24h, 0.2, 2% (1); co-applied, 0.2% (13)

Sodium nitrate: pre-applied, 24h, 0.2% (1)

GA₃: pre-applied, 72h, 10^-6 M (7); pre-applied, 1.5h, 10^-4 M (14)

Kinetin: pre-applied, 24h, 50 ppm (1)

Abscisic acid: pre-applied, 72h, 10^-6-10^-4 M (7)

Thiourea: pre-applied, 3, 5% (12)

Hydrogen peroxide: pre-applied, 24h, 0.4% (1); 72h, 0.01-6% (7)

Light: 100 fc, 9h (1)

Pre-soak: 72h, aerated (7); 100°C, 0.5-6 min (7)

Acetone: pre-applied, 72h (7)

Ethanol: pre-applied, 72h (7)

Chloroform: pre-applied, 72h (7)

Pectinase: pre-applied, 72h (7)

Cellulase: pre-applied, 72h (7)

Tyrosinase: pre-applied, 72h (7)

Scarification: sulphuric acid, 40, 55%, 1h (9); concentrated sulphuric acid (13); sandpaper (13)

Sodium carbonate: pre-applied (12)

Hydrochloric acid: pre-applied, 10^-3 N (12)

Butyric acid: pre-applied, 8x10^-2 N (12)

Pre-dry: 80°C (12)

O. miliacea

Constant temperatures: 20°C, 26°C, 30°C, dark (3); 26°C, 30°C, continuous light (3,8)

Hydrogen peroxide: pre-applied, 90 min (4)

Calcium hypochlorite: pre-applied, 15 min, 10% (18)

IV. Partly-successful dormancy breaking treatments

O. hymenoides

Alternating temperatures: 5°/15°-30°C (15h/9h) (1); 15°/25°C, 20°/30°C (17h/7h) in light (13)

Pre-chill: 5°C, 4w (1,2,6,13); 4-10w (9)

Light: dark (1)

Calcium nitrate: pre-applied, 24h, 0.2% (1)

Nitric acid: pre-applied, 24h, 0.2% (1); pre-applied, 24h, 0.2%, then pre-chill, 5°C, 4w, germinate at 5°/15°C (15h/9h) (1)

GA₃: pre-applied, 24h, 100, 500, 1000 ppm (1); pre-applied, 24h, 10^-6-10^-4 M (7); co-applied, 100 ppm (1)

Kinetin: pre-applied, 72h, 10^-6-10^-4 M (7)

Removal of seed covering structures: (1,12,13); lemma and palea, then prick pericarp (19,20); lemma and palea, then prick pericarp, plus GA₃, co-applied, 100 ppm (19); lemma and palea, then prick pericarp, plus GA₃, co-applied, 100 ppm; plus pre-chill, 5°C, 4w (19)

Scarification: sulphuric acid, 98%, 0.5-1h (7); sulphuric acid, 98%, 0.25-1.25h (9); sulphuric acid, 98%, 0.5-1.25h (12); sulphuric acid, 98%, 0.75h (17); sulphuric acid, 98%, 0.5h (14); sulphuric acid, 67%, 40 min (7); sulphuric acid, 85%, 1h (9,13); sulphuric acid, 70%, 0.75-1h (9,13); sulphuric acid, 98%, 40 min, then GA₃, pre-applied, 70h, 10^-5 M (15); sulphuric acid, 98%, 35 min, then GA₃, pre-applied, 1.5h, 10^-4 M dissolved in acetone (6,14); sulphuric acid, 67%, then GA₃, co-applied, 10^-6-10^-3 M dissolved in acetone (7); sulphuric acid (2); mechanical (2,9,12,15)

Ether: pre-applied, 72h (7)

Pre-soak: 2°-4°C, 40d (11)

Pre-wash: 1-5d (7)

O. miliacea

Alternating temperatures: 20°/30°C (16h/8h) in light (3)

Light: 100-120 fc, 5 min (3,8)

Pre-soak: (16)

Pre-wash: 1-4d (3)

Scarification: concentrated sulphuric acid, 1 min (4); sulphuric acid, 71%, 5-20, 60 min (4); sulphuric acid, 70%, 20-40 min (16)

Removal of seed covering structures: lemma and palea, then scarification, concentrated sulphuric acid, 5 min, germinate at 21°C in light, 12h/d (18)

Sodium hypochlorite: pre-applied, 1,3,4h, 2.5% (4)

Inoculum: Penicillum funiculosum (18)

V. Successful dormancy-breaking treatments

O. hymenoides

Pre-chill, or dark Pre-chill in soil (AOSA)

Constant temperatures: 3°C, 120d (13)

Pre-chill: 5°C, 4w, with GA₃, co-applied, 100 ppm, at 5°/15°C (15h/9h) in dark, 21d (1)

Scarification: sulphuric acid, 71%, 0.75-1h, germinate at 20°/30°C (17h/7h) (13)

Removal of seed covering structures: lemma and palea, then prick pericarp, germinate at 20°C, dark, 7d, then GA₃, co-applied, 50 ppm (20)

O. miliacea

Pre-chill (ISTA)

Light, Pre-chill (AOSA)

Scarification: sulphuric acid, 70%, 20-40 min, germinate at 20°/30°C (16h/8h) (3); sulphuric acid, 70%, 40 min (4)

VI. Comment

The AOSA directions for testing dormant seeds of O. hymenoides require pre-chilling at 5°C for 4 weeks and testing for an additional 3 weeks where paper is the germination test medium: a total germination test period of 13 weeks. This substantial test period is indicative of the dormancy problem in this species. If soil is used as the germination test medium then the direction is to pre-chill the seeds for 2 weeks at 5°C in the dark in soil prior to the subsequent germination test (AOSA): a total germination test period of 8 weeks.

Several of the AOSA prescriptions are, however, unlikely to be completely effective in promoting the germination of the very dormant seeds of O. hymenoides (1). Seeds tend to germinate better when tested in soil compared to paper substrata (1,14), and an alternating temperature regime is promotory compared to a constant temperature of 15°C (1). The following standard germination test procedure has been recommended: test in previously sterilized potting compost re-moistened with 100 ppm GA₃, pre-chill for 4 weeks at 5°C, then germinate at an alternating temperature of 5°/15°C in the dark (1). It is suggested here that the apparent requirement for testing in compost to avoid exposure to excess light may not be necessary, and that testing on a paper germination test medium may be satisfactory if the light regime specified in Chapter 6 is applied.

The AOSA prescribed alternating temperature regime of 20°/30°C (16h/8h) alone is unable to promote the full germination of dormant accessions of O. miliacea (3), but pre-chilling - the AOSA directions suggest 2 weeks at 5°C - combined with lemma and palea removal should be sufficiently promotory. However, despite the AOSA prescription for light care with the light regime is also required for dormant accessions of O. miliacea: germination is inhibited by continuous light treatments but promoted by short light irradiations (8). Consequently testing in the dark is suggested with only a brief exposure to light: a single 4 minute exposure to red light (220 fc at source) 24 hours after imbibition in the dark began can be extremely promotory (8). Again the light regime described in Chapter 6 is suggested as a possible alternative.

VII. References

1. Clark, D.C. and Bass, L.N. (1970). Germination experiment with seeds of Indian Ricegrass, Oryzopsis hymenoides (Roem, and Schult.) Ricker. Proceedings of the Association of Official Seed Analysts, 60, 226-239.

2. Huntamer, M.Z. (1934). Dormancy and delayed germination of Oryzopsis hymenoides. Thesis, State College of Washington, Pullman, Washington.

3. Koller, D. and Negbi, M. (1959). The regulation of germination of Oryzopsis miliacea. Ecology, 40, 20-36.

4. Laude, H.M. (1951). Treatments to improve the emergence and stand of smilograss. Journal of Range Management, 4, 88-92.

5. Laude, H.M. (1956). Germination of freshly harvested seed of some Western Range species. Journal of Range Management, 9, 126-129.

6. McDonald, M.B. Jr. (1976). Improving the germination of Indian ricegrass seeds. Journal of Seed Technology, 1, 46-53.

7. McDonald, M.B. Jr. and Khan, A.A. (1977). Factors determining germination of Indian ricegrass seeds. Agronomy Journal, 69, 558-563

8. Negbi, M. and Koller, D. (1964). Dual action of white light in the photocontrol of germination of Oryzopsis miliacea. Plant Physiology, 39, 247-253.

9. Plummer, A.P. and Frischnecht, N.C. (1952). Increasing field stands of Indian ricegrass. Agronomy Journal, 44, 285-289.

10. Quinones, F.A. (1980). Seed germination and production of range species for use in revegetation. Bulletin, New Mexico Agricultural Experiment Station, Bulletin No. 670, 28pp.

11. Rogler, G.A. (1960). Relation of seed dormancy of Indian ricegrass (Oryzopsis hymenoides (Roem. and Schult.)) to age and treatment. Agronomy Journal, 52, 470-473.

12. Stoddart, L.A. and Wilkinson, K.J. (1938). Inducing germination in Oryzopsis hymenoides for range reseeding. Journal of the American Society of Agronomy, 30, 763-768.

13. Toole, V.K. (1940). The germination of seed of Oryzopsis hymenoides. Journal of the American Society of Agronomy, 32, 33-41.

14. Zematra, R.S., Havstad, C. and Cuany, R.L. (1983). Reducing seed dormancy in Indian ricegrass (Oryzopsis hymenoides). Journal of Rang Management, 36, 239-241.

15. Barton, L.V., Roe, C.H. and Khan, A.A. (1971). Imbibition and germination: influence of hard seed coats on RNA metabolism. Physiologia Plantarum, 25, 402-406.

16. Lapeyronie, A. (1968). Existence d'un cycle endogène concernant la faculté germinative de l' Oryzopsis miliacea. Comptes Rendus Hebdomadaires des Séances de l'Académie de Science, Paris, 267D, 1724-1726.

17. McDonald, M.B. Jr. and Khan, A.A. (1983). Acid scarification and protein synthesis during seed germination. Agronomy Journal, 75, 111-114.

18. Probert, R.J. (1981). The promotive effects of a mould, Penicillium funiculosum Thom. on the germination of Oryzopsis miliacea (L.) Asch. & Schw. Annals of Botany, 48, 85-88.

19. Young, J.A. and Evans, R.A. (1984). Germination of seeds of 'Paloma' and 'Nezpar' Indian ricegrass. Journal of Range Management, 37, 19-21.

20. Young, J.A., Evans, R.A. and Roundy, B.A. (1983). Quantity and germinability of Oryzopsis hymenoides seed in Lahontan sands. Journal of Range Management, 36, 82-86.

PANICUM

P. anceps Michx.	beaked panicum
P. antidotale Retz.	blue panic grass
P. bisulcatum Thunb.
P. bulbosum HBK
P. capillare L.	witch grass
P. clandestinum L.	deertongue grass
P. coloratum Stapf	kleingrass
P. dichotomiflorum Michx.	fall panicum
P. fasciculatum	brown top millet
P. maximum Jacq.	guinea grass, green panic
P. miliaceum L.	common millet, broom-corn millet, brown-corn millet, hog millet, proso millet, Russian millet
P. obtusum HBK	vine-mesquite
P. phillopogon
P. prolutum
P. ramosum L.
P. simile Domin
P. turgidum Forsk.
P. virgatum L.	switch-grass

I. Evidence of dormancy

Freshly harvested seeds of Panicum spp. can show considerable dormancy and consequently can be difficult to germinate (1,2,4,5,7,10-13, 15,16,21,22,23,26,34,35,39,40,46). An indication of the degree of dormancy is provided by the large number of treatments listed below which failed to break dormancy and the observations that substantial periods of after-ripening are required to completely remove dormancy. For example, 10 (13), 12 (22), 18 (33) or 30 (43) months treatment has been required by various seed lots of P. maximum. A further example which indicates the severity of the problem is a failure to achieve more than 2-3% germination in high-viability lots of P. virgatum and P. bisulcatum after one year's storage despite eight different germination test environments (21).

II. Germination regimes for non-dormant seeds

P. antidotale

TP: 20°/30°C: 28d (ISTA)

TP; TS: 20°/30°C (16h/8h): 28d (AOSA)

P. bisulcatum

Constant temperatures: 15°-30°C (21)

P. bulbosum

Constant temperatures: 15°-25°C (21)

P. coloratum

TP: 20°/35°C (16h/8h): 28d (ISTA)

P. maximum

TP: 20°/30°C; 15°/35°C (16h/8h): 28d (ISTA)

TP: 15°/35°C (16h/8h): 28d (AOSA)

P. miliaceum

BP; TP: 25°C; 20°/30°C (16h/8h): 7d (ISTA)

BP; TP: 20°/30°C (16h/8h): 7d (AOSA)

P. ramosum

BP: 20°/30°C (16h/8h): 14d (ISTA)

P. virgatum

TP: 15°/30°C (16h/8h): 28d (ISTA)

TP; TS: 15°/30°C (16h/8h): 28d (AOSA)

III. Unsuccessful dormancy-breaking treatments

P. anceps

Constant temperatures: 15°C, 20°C, 30°C (10)

Alternating temperatures: 10°/20°C, 20°/30°C (16h/8h) (10)

Potassium nitrate: pre-applied, 0.2% (10)

Sodium hydroxide: pre-applied, 35% (10)

Mercuric chloride: pre-applied, 0.025% (10)

Oxygen: pre-applied (10)

Ether: pre-applied (10)

Pre-soak: (10)

Pre-dry: (10)