The Cruciferae comprise roughly 3000 species of herbaceous plants within more than 300 genera. They provide numerous leaf vegetables (e.g. Brassica chinensis L., Chinese cabbage), edible roots (e.g. Raphanus sativus L., radish), condiments (e.g. Armoracia rusticana Gaertn.) and oil crops (e.g. Brassica campestris L., field mustard). The fruits are usually dehiscent pod-like capsules: if they are longer than they are broad they are called a siliqua; if they are as broad as they are long they are called a silicula. The seeds show orthodox storage characteristics.
SEED DORMANCY AND GERMINATION
Dormancy is a potential problem for most accessions of the Cruciferae. The seeds have a curved embryo and no endosperm. B.R. Atwater classifies seed morphology as non-endospermic seeds with axile foliar embryos enclosed within thin, mucilaginous seed coats (see Table 17.2, Chapter 17). Promotory treatments include potassium nitrate, light, pre-chilling and alternating temperatures.
Detailed information is provided in this chapter for the genera Barbarea (including synonyms within Erysimum), Brassica (including synonyms within Eruca and Sinapis), Crambe, Lepidium, Nasturtium (including synonyms within Radicula, Rorippa and Sisymbrium) and Raphanus. Further information is provided for additional species (including some of the synonyms listed above) in Table 32.1. For difficult accessions and other species the algorithm below may enable a suitable germination test procedure to be developed.
RBG Kew Wakehurst Place algorithm
The first and second steps of the algorithm are dependent upon the accession's origin. Temperate accessions are tested at constant temperatures of 11°C, 16°C and 31°C with light applied for 12h/d. If the results suggest a trend in the response of germination to constant temperatures then further samples of seeds are tested at intermediate, or more extreme constant temperatures. For example, if germination is greatest at 11°C then a further sample of seeds is tested at 6°C with light applied for 12h/d. Tropical accessions are tested at constant temperature of 21°C and 26°C with light applied for 12h/d. Again, if a trend in the results is apparent then a further sample of seeds is tested at a more extreme constant temperature. If it is not possible to distinguish between temperate and tropical accessions then five samples of the seeds are tested at each constant temperature regime: that is at 11°C, 16°C, 21°C, 26°C and at 31°C.
If the first step of the algorithm does not result in full germination then the second step is to test a further sample of seeds in an alternating temperature regime: temperate accessions are tested at 23°/9°C (12h/12h); tropical accessions at 33°/19°C (12h/12h); in each regime light is applied for 12h/d during the period spent at the upper temperature. If it is not possible to distinguish between temperate and tropical accessions then test seeds in both alternating-temperature regimes.
Further steps in the algorithm do not distinguish between temperate and tropical accessions. If full germination has not been promoted by the second step of the algorithm then the third step of the algorithm is to pre-chill a further sample of seeds at 2° to 6°C for 8w, and then test for germination in the most successful regime determined in steps one and two.
If full germination has not been promoted then the fourth step of the algorithm is to remove the seed coats from a fresh sample of seeds and test in the most successful regime determined from the results of steps one to three. This may include a pre-chill treatment if this resulted in an increase in germination in step three.
If full germination has not been promoted by step four then the fifth step of the algorithm is to co-apply 7 x 10-4 M GA3 in the germination test substrate and test at the most successful regime determined in steps one to four.
If full germination has not been promoted, the sixth step of the algorithm is to estimate viability using a tetrazolium test (see Chapter 11, Volume I).
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 the six genera in this chapter, from Table 17.2 and from Table 32.1.
TABLE 32.1 Summary of germination test recommendations for species within the Cruciferae
|
Species and Authority |
Substrate |
Temperature |
Duration |
Additional directions |
Source |
|
Alyssum argenteum All. |
TP |
20°/30°C; 15°C; 20°C |
21d |
pre-chill, potassium nitrate |
ISTA |
|
Alyssum compactum De Not. |
TP |
15°C |
8d |
light, potassium nitrate |
AOSA |
|
Alyssum montanum L. |
TP |
20°/30°C; 15°C; 20°C |
21d |
pre-chill, potassium nitrate |
ISTA |
|
Alyssum saxatile L.
|
TP |
20°/30°C; 15°C; 20°C |
21d |
pre-chill, potassium nitrate |
ISTA |
|
TP |
15°C |
8d |
light, potassium nitrate |
AOSA |
|
|
Arabis alpina L.
|
TP |
20°/30°C; 15°C |
21d |
pre-chill, potassium nitrate |
ISTA |
|
TP |
15°C |
14d |
light, potassium nitrate |
AOSA |
|
|
|
15°C |
21d |
light, potassium nitrate, 0.2% |
Atwater |
|
|
Arabis x arendsii Wehrhahn |
TP |
20°/30°C; 15°C |
21d |
pre-chill, potassium nitrate |
ISTA |
|
Arabis blepharophylla Hook. & Arn. |
TP |
20°/30°C; 15°C |
21d |
pre-chill, potassium nitrate |
ISTA |
|
Arabis caucasica Willd. |
TP |
20°/30°C; 15°C |
21d |
pre-chill, potassium nitrate |
ISTA |
|
Arabis glabra |
TP |
20°/30°C |
14d |
light |
SGCF |
|
Arabis holboelli |
TP |
20°/30°C; 15°C; 20°C |
|
pre-chill, 2, 3w |
M&O |
|
Arabis procurrens Waldst. & Kit. |
TP |
20°/30°C; 15°C |
21d |
pre-chill, potassium nitrate |
ISTA |
|
Arabis scopoliana Boiss. |
TP |
20°/30°C; 15°C |
21d |
pre-chill, potassium nitrate |
ISTA |
|
Aubrieta deltoidea DC.
|
TP |
10°C; 15°C; 20°C |
21d |
pre-chill |
ISTA |
|
TP |
15°C |
18d |
sensitive to warm temperatures |
AOSA |
|
|
|
15°C |
21d |
light |
Atwater |
|
|
Aurina saxatile (L.) Desv. |
|
15°C |
14d |
potassium nitrate, 0.2% |
Atwater |
|
Berteroa incana |
TP |
20°C |
10d |
potassium nitrate |
SGCF |
|
Camelina microcarpa
|
TP |
20°/30°C |
14d |
potassium nitrate, pre-chill, 2w |
SGCF |
|
TP |
15°C; 20°C |
|
|
M&O |
|
|
Camelina sativa (L.) Crantz |
TP |
20°/30°C |
10d |
|
ISTA |
|
Capsella bursa-pastoris L. |
TP |
20°/30°C |
21d |
potassium nitrate, pre-chill, 2w |
SGCF |
|
Cardaria draba |
TP |
20°/30°C; 15°C |
|
light |
M&O |
|
Cardaria draba var repens |
TP |
15°C |
|
light |
M&O |
|
Cardaria pubescens |
TP |
20°/30°C |
|
light |
M&O |
|
Cheiranthus cheiri L. |
TP |
20°/30°C; 15°C; 20°C |
14d |
light, potassium nitrate, pre-chill |
ISTA |
|
TP |
20°/30°C |
10d |
light, potassium nitrate |
AOSA |
|
|
|
20°C |
10d |
light, potassium nitrate, 0.2% |
Atwater |
|
|
Descurainia pinnata |
TP |
20°/30°C; 20°C |
|
|
M&O |
|
Eruca sativa Mill.
|
TP; BP |
20°C |
7d |
|
ISTA |
|
BP |
20°C |
7d |
|
AOSA |
|
|
TP |
20°C |
7d |
|
Heit |
|
|
Erysimum x allionii Hort.
|
TP |
20°/30°C; 15°C; 20°C |
14d |
pre-chill, potassium nitrate |
ISTA |
|
TP |
20°/30°C |
10d |
|
AOSA |
|
|
Erysimum cheiranthoides |
TP |
20°/30°C |
7d |
potassium nitrate |
SGCF |
|
Hesperis matronalis L.
|
TP |
20°/30°C; 20°C |
14d |
pre-chill, potassium nitrate |
ISTA |
|
TP |
20°/30°C |
8d |
light, potassium nitrate |
AOSA |
|
|
TP |
20°/30°C |
7d |
potassium nitrate |
SGCF |
|
|
Iberis amara L. |
TP; BP |
20°/30°C; 15°C; 20°C |
14d |
pre-chill, potassium nitrate |
ISTA |
|
TP |
15°C |
14d |
|
AOSA |
|
|
|
20°C |
14d |
test at 15°C |
Atwater |
|
|
Iberis gibraltarica L.
|
TP; BP |
20°/30°C; 15°C; 20°C |
14d |
pre-chill, potassium nitrate |
ISTA |
|
TP |
15°C |
21d |
potassium nitrate |
AOSA |
|
|
Iberis sempervirens L.
|
TP; BP |
20°/30°C; 15°C; 20°C |
14d |
pre-chill, potassium nitrate |
ISTA |
|
TP |
15°C |
21d |
potassium nitrate |
AOSA |
|
|
Iberis umbellata L.
|
TP; BP |
20°/30°C; 15°C; 20°C |
14d |
pre-chill, potassium nitrate |
ISTA |
|
TP |
15°C |
14d |
|
AOSA |
|
|
Lesquerella fendleri (Gray) Wats. |
|
15°/25°C |
|
light, potassium nitrate, 0.2%, GA, 100ppm |
Atwater |
|
Lesquerella gordonii (Gray) Wats. |
|
15°/25°C |
|
light, GA, 100ppm |
Atwater |
|
Lesquerella palmeri Wats. |
|
10°/30°C |
|
light, GA, 1000ppm |
Atwater |
|
Lobularia maritima (L.) Desv. |
TP |
20°/30°C; 15°C; 20°C |
21d |
pre-chill, potassium nitrate |
ISTA |
|
TP |
15°C |
8d |
light, potassium nitrate |
AOSA |
|
|
|
15°C |
14d |
potassium nitrate, 0.2%, or GA, 400ppm |
Atwater |
|
|
Lunaria annua L.
|
TP; BP |
15°C; 20°C |
21d |
pre-chill, potassium nitrate |
ISTA |
|
TP |
15°C |
14d |
potassium nitrate |
AOSA |
|
|
|
20°C |
14d |
GA, 400ppm |
Atwater |
|
|
Lunaria vulgaris Mill. |
TP; BP |
15°C; 20°C |
21d |
|
ISTA |
|
Malcolmia maritima (L.) R. Br. |
TP |
20°/30°C; 15°C; 20°C |
14d |
light, pre-chill, potassium nitrate |
ISTA |
|
TP |
20°/30°C |
8d |
light |
AOSA |
|
|
|
20°C |
7d |
test at 15°C |
Atwater |
|
|
Matthiola incana (L.) R. Br. |
TP |
20°/30°C; 20°C |
14d |
pre-chill, potassium nitrate |
ISTA |
|
TP |
20°/30°C; 20°C |
7d |
light, sensitive to drying out in test |
AOSA |
|
|
|
15°C; 20°C |
10d |
light, potassium nitrate, 0.2% |
Atwater |
|
|
Matthiola longipetala (Vent.) DC. |
TP |
20°/30°C; 15°C; 20°C |
14d |
pre-chill, potassium nitrate |
ISTA |
|
TP |
15°C |
8d |
light, potassium nitrate |
AOSA |
|
|
|
15°C |
10d |
potassium nitrate, 0.2% |
Atwater |
|
|
Sisymbrium altissimum
|
TP |
20°/30°C; 20°C |
|
|
M&O |
|
TP |
20°/30°C |
8d |
potassium nitrate, pre-chill |
SGCF |
|
|
TP; S |
20°/30°C |
7d |
light |
Everson |
|
|
Sisymbrium officinale
|
TP |
20°/30°C |
|
light |
M&O |
|
TP |
20°/30°C |
10d |
potassium nitrate, pre-chill |
SGCF |
|
|
TP; S |
15°/30°C |
10d |
light |
Everson |
|
|
Thlaspe arvense
|
TP |
20°/30°C |
10d |
potassium nitrate |
SGCF |
|
S |
15°/30°C |
10d |
light |
Everson |
BARBAREA
|
B. orthoceras |
erectpod wintercress |
|
B. verna (Mill.) Aschers. [B. praecox R. Br.;
Erysimum vernum Mill.] |
early cress, Belle Isle cress upland cress,
wintercres |
|
B. vulgaris R. Br. [Erysimum Barbarea
L.] |
yellow rocket, spring mustard |
I. Evidence of dormancy
Freshly harvested seeds of Barbarea spp. can show considerable dormancy (1,2,5). Seeds of B. vulgaris require 4 months after-ripening at room temperature to lose dormancy (2).
II. Germination regimes for non-dormant seeds
B. verna
TP: 20°/30°C (16h/8h): 7d (AOSA)
III. Unsuccessful dormancy-breaking treatments
B. verna
Constant temperatures: 10°-35°C (6)
Alternating temperatures: 20°/30°C (17h/7h) in light or dark (6); 20°/35°C (17h/7h) in dark (6)
Warm stratification: 20°C, 3d, dark, then 40°C, 1-8 min (5)
Sodium nitrite: co-applied, 10-3 M (1)
Hydroxylamine hydrochloride: co-applied, 3.2x10-4 M (1)
Ethylene: co-applied, 1, 10, 100 ppm (4)
B. vulgaris
Constant temperatures: 20°C, 25°C, 30°C (2)
Warm stratification: 20°C, 3d, dark, then 40°C, 1-16 min (5)
Potassium nitrate: co-applied, 10-2 M (1)
Sodium nitrite: co-applied, 10-3 M (1)
Hydroxylamine hydrochloride: co-applied, 3.2x10-4 M (1)
Ethylene: co-applied, 1, 10, 100 ppm (4)Light: far red (7)
IV. Partly-successful dormancy-breaking treatments
B. orthoceras
Constant temperatures: 15°C, 20°C, dark (8)
Alternating temperatures: 20°/30°C, in light or dark (8)
Pre-chill: 3°C, 7-28d, germinate at 20°/30°C, dark (8)
B. verna
Warm stratification: 20°C, 3d, dark, then 40°C, 16 min-6h (5)
Potassium nitrate: co-applied, 10-2 M (1); co-applied, 0.2%, at 20°/30°C (17h/7h), dark (6)
Ammonium chloride: co-applied, 5x10-2 -10-3 M (1)
Ammonium nitrate: co-applied, 10-2 M (1)
Sodium nitrate: co-applied, 10-2 M (1)
Light: (4); 0.4-3.3x10-9 mol cm-2 s-1, 20s, 5 min (5)
B. vulgaris
Warm stratification: 20°C, 3d, then 40°C, 32 min-6h (5)
Ammonium chloride: co-applied, 10-2 M (1)
Potassium nitrate: co-applied, 0.2% (2)
Light: (4); 50 fc (2); 0.4-3.3x10-9 mol cm-2 s-1, 20s, 5 min (5); red, 16 min (7)
V. Successful dormancy-breaking treatments
B. verna
Potassium nitrate, Light (AOSA)
Warm stratification: 20°C, 3d, then 40°C, 64 min, in light, 4x10-7 mol cm-2 s-1 (5); 10°-35°C, 28d, germinate at 20°/30°C, 20°/35°C (17h/7h) in light, plus potassium nitrate, co-applied, 0.2% (6)
Potassium nitrate: co-applied, 0.2%, at 20°/30°C, 20°/35°C (17h/7h) in light (6)
B. vulgaris
Alternating temperatures: 20°/30°C (16h/8h) in light (3)
VI. Comment
Successful germination of dormant seeds of B. verna and B. vulgaris requires alternating temperatures and light (2,3,6). Ammonium nitrate and ammonium chloride are reported to be more effective in promoting the germination of dormant seeds than potassium nitrate (1).
Consequently if the AOSA procedure for B. verna - potassium nitrate, co-applied, 0.2%, in an alternating temperature regime of 20°/30°C (16h/8h) in light (but see Chapter 6) does not prove satisfactory try replacing potassium nitrate with ammonium nitrate (10-2 M).
The AOSA procedure for B. verna appears to be satisfactory for seeds of B. vulgaris. Pre-chilling dormant seeds of B. orthoceras at 3°C for between 21 and 28 days with subsequent testing for germination in an alternating temperature regime of 20°/30°C is an effective procedure for breaking dormancy (8) and is suggested here. The germination tests should be carried out in the dark, however, since light can inhibit seed germination in this regime (8).
VII. References
1. Hendricks, S.B. and Taylorson, R.B. (1974). Promotion of seed germination by nitrate, nitrite, hydroxylamine, and ammonium salts. Plant Physiology, 54, 304-309.
2. Steinbauer, G.P. and Frank, P. (1954). Primary dormancy and germination requirements of seeds of certain Cruciferae. Proceedings of the Association of Official Seed Analysts, 44, 176-181.
3. Steinbauer, G.P., Grigsby, B., Correa, L. and Frank, P. (1955). A study of methods for obtaining laboratory germination of certain weed seeds. Proceedings of the Association of Official Seed Analysts, 45, 48-51.
4. Taylorson, R.B. (1979). Response of weed seeds to ethylene and related hydrocarbons. Weed Science, 27, 7-10.
5. Taylorson, R.B. and Hendricks, S.B. (1972). Interactions of light and a temperature shift on seed germination. Plant Physiology, 49, 127-130.
6. Toole, E.H. and Toole, V.K. (1940). Note on the germination of seeds of Barbarea verna and Lepidium virginicum. Proceedings of International Seed Testing Association, 12, 32-38.
7. Toole, E.H., Toole, V.K., Hendricks, S.B. and Borthwick, H.A. (1957). Effect of temperature on germination of light-sensitive seeds. Proceedings of the International Seed Testing Association, 22, 196-204.
8. Maguire, J.D. and Overland, A. (1959). Laboratory germination of seeds of weedy and native plants. Washington Agricultural Experiment Station, Circular No. 349, 15 pp.
BRASSICA
|
B. alba (L.) Rabenh. [B. hirta Moench;
Sinapis alba L.] |
white mustard |
|
B. campestris L. |
field mustard |
|
B. chinensis L. |
Chinese cabbage, pakchoi |
|
B. chinensis L. var pekinensis (Rupr.) Sun
[B. pekinensis Rupr.; B. Pe-Tsai Bailey; |
pe-tsai Sinapis pekinensis Lour.] |
|
B. juncea (L.) Czern.& Coss. [B. rugosa
Hort.; Sinapis juncea L.;] |
leaf mustard, Indian mustard |
|
B. juncea (L.) Czern.& Coss. var crispifolia
Bailey [B. japonica Hort.] |
|
|
B. kaber (DC.) Wheeler [B. arvensis Rabenh.;
Sinapis kaber DC.; Sinapis arvensis L.] |
charlock, wild mustard |
|
B. napella Chaix |
rape |
|
B. napus L. |
annual rape, winter rape, colza |
|
B. napus L. var napobrassica (L.) Reichb. [B.
Napobrassica Mill.; B. oleracea L. var Napobrassica
L.] |
rutabaga, swede |
|
B. napus L. var oleifera |
|
|
B. nigra Koch [B. cernua Coss.; Sinapis
nigra L.; Sinapis cernuaThunb.] |
black mustard |
|
B. oleracea L. var acephala DC. |
borecole, collard, kale |
|
B. oleracea L. var acephala DC. |
borecole, collard, kale |
|
B. oleracea L. var alboglabra (Bailey)
Musil. |
Chinese kale |
|
B. oleracea L. var botrytis L. [B.
cauliflora Gars.; B. botrytis Mill.] |
broccoli, cauliflower |
|
B. oleracea L. var capitata L. |
cabbage |
|
B. oleracea L. var gemnifera DC. |
brussel sprouts |
|
B. oleracea L. var gongylodes L. [B.
caulorapa Pasq.; B. oleracea L. var caulo-rapa DC.] |
kohlrabi |
|
B. oleracea L. var sabauda |
savoy cabbage |
|
B. oleracea L. var tronchuda Bailey |
tronchuda cabbage, Portuguese kale |
|
B. perviridis (Bailey) Bailey |
spinach mustard |
|
B. rapa L. [B. campestris L. var rapifera
Metz.] |
turnip |
|
B. spinescens Pomel |
|
|
B. tournefortii Gouan |
|
|
B. vesicaria [Eruca vesicaria (L.)
Cav.] |
|
I. Evidence of dormancy
Seeds of the cultivated Brassica spp. can show considerable dormancy (7-9,14,25,26,30-33,35,37,41,44-50,52,54). This causes problems in both commercial seed testing stations and plant breeding programmes (5,38,54). A dormancy period of 2-3 months has been reported for seeds of B. napus and B. nigra, but dormancy can remain for as long as 2 years when the whole fruits are stored (47). Seeds of B. campestris, B. nigra and B. juncea require at least 7 months after-ripening at room temperature to remove dormancy (52). Not surprisingly the wild species of Brassica show much deeper dormancy, e.g. B. kaber (6,12,13,16,32,38,53,55), B. spinescens (40), B. tournefortii (40) and B. vesicaria (40). Secondary dormancy is reported to be induced by high carbon dioxide concentrations (19-21), by high temperatures (35), or by prolonged pre-chilling (35). Certain seed drying regimes can also induce dormancy (50).
II. Germination regimes for non-dormant seeds
B. chinensis, B. chinensis var pekinensis
TP: 20°/30°C (16h/8h); 20°C: 7d (ISTA)
BP: 20°/30°C (16h/8h): 7d (AOSA)
B. juncea
TP: 20°/30°C (16h/8h); 20°C: 7d (ISTA)
TP: 20°/30°C (16h/8h): 7d (AOSA)
B. napus
TP: 20°/30°C (16h/8h); 20°C: 7d (ISTA)
BP: 20°/30°C (16h/8h): 7d (AOSA)
Alternating temperatures: 20°/30°C, 18°/25°C (16h/8h) (18)
B. napus var napobrassica
TP: 20°/30°C (16h/8h); 20°C: 14d (ISTA)
TP; BP: 20°/30°C (16h/8h): 14d (AOSA)
Alternating temperatures: 20°/30°C (16h/8h) (18)
B. napus var oleifera
Alternating temperatures: 15°/25°C, 20°/30°C (16h/8h) (23)
B. nigra
TP: 20°/30°C (16h/8h); 20°C: 10d (ISTA)
TP: 20°/30°C (16h/8h): 7d (AOSA)
B. oleracea var acephala
TP: 20°/30°C (16h/8h); 20°C: 10d (ISTA)
TP; BP: 20°/30°C (16h/8h): 10d (AOSA)
Constant temperatures: 5°-17°C (2)
B. oleracea var alboglabra
TP: 20°/30°C (16h/8h); 20°C: 10d (ISTA)
TP; BP: 20°/30°C (16h/8h): 10d (AOSA)
B. oleracea var botrytis
TP: 20°/30°C (16h/8h); 20°C: 10d (ISTA)
TP; BP: 20°/30°C (16h/8h): 10d (AOSA)
Constant temperatures: 5°-17°C (2); 20°C (15); 7.5°-32.5°C (43)
Alternating temperatures: 15°/25°C, 20°/30°C (16h/8h) (23)
B. oleracea var capitata
TP: 20°/30°C (16h/8h); 20°C: 10d (ISTA)
TP; BP: 20°/30°C (16h/8h): 10d (AOSA)
Constant temperatures: 7.5°-32.5°C (43)
B. oleracea var gemnifera
TP: 20°/30°C (16h/8h); 20°C: 10d (ISTA)
TP; BP: 20°/30°C (16h/8h): 10d (AOSA)
Constant temperatures: 5°-17°C (2); 20°C (15); 7.5°-32.5°C (43)
B. oleracea var gongylodes
TP: 20°/30°C (16h/8h); 20°C: 10d (ISTA)
TP; BP: 20°/30°C (16h/8h): 10d (AOSA)
Constant temperatures: 30°C (36)
B. oleracea var sabauda
Constant temperatures: 5°-17°C in light, 8h/d (2)
B. oleracea var tronchuda
TP: 20°/30°C (16h/8h); 20°C: 10d (ISTA)
TP; BP: 20°/30°C (16h/8h): 10d (AOSA)
B. perviridis
TP: 20°/30°C (16h/8h); 20°C: 7d (ISTA)
BP: 20°/30°C (16h/8h): 7d (AOSA)
B. rapa
TP: 20°/30°C (16h/8h); 20°C: 7d (ISTA)
BP: 20°/30°C (16h/8h): 7-10d (AOSA)
Constant temperatures: 5°-17°C (2); 15°-35°C (10)
III. Unsuccessful dormancy-breaking treatments
B. alba
Pre-chill: 1°-3°C, 3d (21)
Warm stratification: 50°C, 3h (21)
Pre-soak: (40)
Light: white, continuous, 150x10-6 mol m-2 s-1 (26); red, continuous, 2x10-5 mol m-2 s-1 (26); blue, continuous, 2x10-5 mol m-2 s-1 (26)
Carbon dioxide: 3-24% (19,20); 9-12%, plus oxygen, 5% (20); 5-90%, plus oxygen, 10% (21)
B. campestris
Light: continuous, 50 fc (38)
B. juncea
Constant temperatures: 35°C, red light (27); 30°C, 35°C, dark (27)
Ethylene: co-applied, 1, 10, 100 ppm (42)
B. kaber
Constant temperatures: 23°C and above (53)
Light: far red (1); far red, 4h (13)
GA3: co-applied, 500 ppm (4)
Naphthaleneacetic acid: co-applied, 10-2 -10-7 M (12)
Ethylene: co-applied, 1-100 ppm (42)
Oxygen: 2.5% (11)
Ethanol: 1 ppm, plus acetone, 0.1 ppm plus acetaldehyde (11)
Mannitol: co-applied, 0.2 M (13)
Ultrasonics: 20 kc/s, 30s-5 min (12)
Liquid nitrogen: 10s (12)
B. napella
Removal of seed covering structures: (41)
Carbon dioxide: (41)
B. nigra
Constant temperatures: 25°C (48); 25°C, 30°C (35)
Pre-chill: 6°C, 20d (35)
Potassium nitrate: co-applied, 0.2% (52); co-applied, 0.2%, at 25°C, 30°C (35)
Indoleacetic acid: co-applied, 50, 100 ppm (34)
Kinetin: co-applied, 50, 100 ppm (34)
B. oleracea var capitata
Scarification: concentrated sulphuric acid, 15,30 min, 4°C (5)
Carbon dioxide: 25-44% (19)
B. rapa
Pre-chill: 10°C, 3d, germinate at 20°/30°C (16h/8h) in light (33)
B. tournefortii
Light: (40)
IV. Partly-successful dormancy-breaking treatments
B. alba
Pre-chill: -4°C, 3h (21); -7°C, 5h (21)
Hydrochloric acid: co-applied, 10-3, 10-2 N (21)
Propionic acid: co-applied, 10-3, 10-2 N (21)
Removal of seed covering structures: (21,22)
Light: dark (26); continuous light, 1.5x10-4 mol m-2 s-1, 26°C (26)
B. campestris
Constant temperatures: 5°-30°C (52); 20°C (9)
Alternating temperatures: 15°/25°C, 20°/30°C, 20°/35°C, 20°/40°C (16h/8h), in daylight or dark (52); 20°/30°C, 15°/25°C (16h/8h) (9)
Potassium nitrate: co-applied, 0.2% (38,52)
Scarification: sulphuric acid (38)
Removal of seed covering structures: (38)
Light: daylight (52)
B. chinensis
Constant temperatures: 20°C (7)
Alternating temperatures: 20°/30°C (16h/8h) (7); 10°/32°C (16h/8h) (7)
Pre-dry: 35°C, 5-7d (7)
B. juncea
Constant temperatures: 20°C, 25°C, 30°C, red light (27); 15°C, 20°C, 25°C, dark (27); 20°-30°C (52)
Alternating temperatures: 20°/30°C in light (25,52); 20°/30°C (16h/8h) in red light or dark (27); 20°/35°C, 20°/40°C (16h/8h) (52)
Pre-chill: 3°-5°C, 2d (30); 5°C, 2d (45)
Light: (30,51,52); 1500 lux, 8h/d (42); red, 1.9x10-4 W cm-2, 5 min, after 24h dark imbibition (42)
Potassium nitrate: co-applied, 0.2%, at 20°C (30,52)
Thiourea: co-applied, 0.5%, at 20°C in dark (30)
GA3: co-applied, 50 ppm (30); co-applied, 100 ppm, at 20°C in light (30)
Removal of seed covering structures: (45); slit seed coat (45); slit seed coat, then pre-soak (45)
Pre-soak: 17h (45)
B. juncea var crispifolia
Constant temperatures: 5°C, 25°C, 35°C (49)
Alternating temperatures: (48)
B. kaber
Constant temperatures: 25°C in light (3); 1°-10°C (6); 18°-27°C, scarified seeds (6); 20°C, light or dark (32); 10°C, 14°C, 20°C, 26°C (53)
Alternating temperatures: 1°-10°/18°-27°C (16h/8h) (6); 10°/30°C (16h/8h) (16); 20°/30°C (16h/8h) in light (32,38)
Pre-chill: 6°C, 1-7d (6); 1°-7°C, 6m (32)
Pre-soak: 35°C, 100 min (12)
Potassium nitrate: co-applied (17); co-applied, 0.2% (38)
Thiourea: co-applied (17); co-applied, 10-2 -10-7 M (12)
GA3: co-applied (17); co-applied, 10-4 M (13); co-applied, 10-200 ppm (55); pre-applied, 24h, 100, 500 ppm (6); pre-applied, 2,6h, 2000 ppm (6); pre-applied, 24h, 50-1000 ppm, plus sucrose, 2% (6)
Kinetin: co-applied, 10-2 -10-7 M (12)
Sodium hypochlorite: pre-applied, 15-120 min, 6%, germinate at 10°/30°C (16h/8h) in dark (16); pre-applied, 90,120 min, 6%, germinate at 10°/30°C (16h/8h) in light (16)
Sucrose: pre-applied, 24h, 2% (6)
Scarification: concentrated sulphuric acid (38); concentrated sulphuric acid, 5-30 min (6); concentrated sulphuric acid, 1-4 min (32)
Light: incandescent, 2.3x10-3 W cm-2, 12h/d, at 25°C (3); fluorescent, 1.3x104 ergs cm-2 s-1, 8h/d (16); diffuse daylight (32); 1500 lux, 8h/d (42); red, 5 min (1); red, 1, 2h (13); red, 1.9x10-4 W cm-2, 5 min, after 24h dark imbibition (42); infra red, 1-30s (12)
B. napella
Constant temperatures: 20°-35°C (41)
Pre-chill: 4°C (41)
Scarification: sulphuric acid (41)
Pre-soak: (41)
Alcohol: (41)
Oxygen: (41)
Hydrogen peroxide: (41)
B. napus
Constant temperatures: 5°C, 25°C, 35°C (49)
Light: fluorescent, at 25°C (29)
B. napus var naprobrassica
Constant temperatures: 20°C in daylight (44)
Alternating temperatures: 20°/30°C (16h/8h) (44)
Light: daylight (8)
B. nigra
Constant temperatures: 20°C, dark (44); 5°-30°C (52); 20°C in daylight (35)
Alternating temperatures: (48); 20°/30°C (16h/8h) (38); 15°/25°C, 20°/30°C, 20°/35°C, 20°/40°C (16h/8h) (52); 15°/25° (16h/8h) (35)
Pre-chill: 10°C (8)
Urea: co-applied, 0.5% (28)
Potassium nitrate: co-applied, 0.3% (28); co-applied, 0.2% (37,38); co-applied, 0.2%, at 15°C, 20°C (35)
Thiourea: co-applied, 0.2% (28)
GA3: co-applied, 50, 100 ppm (34)
Light: daylight (8,51); 50 fc (38)
B. oleracea
Light: daylight (8)
B. oleracea var acephala
Constant temperatures: 20°C in dark (44)
Alternating temperatures: 20°/30°C (16h/8h) in dark (44)
Light: daylight (44)
B. oleracea var botrytis
Constant temperatures: 11°C (24); 20°C in daylight (44)
Alternating temperatures: 20°/30°C in dark (44)
B. oleracea var capitata
Constant temperatures: 20°C (9,44); 8°C (24)
Alternating temperatures: 20°/30°C, 15°/25°C (16h/8h) (9); 20°/30°C (16h/8h) in dark (44)
Pre-chill: 3°-5°C, 2d (30)
Light: (30)
Thiourea: co-applied, 0.5%, at 20°C in dark (30)
Potassium nitrate: co-applied, 0.2% (30)
Scarification: concentrated sulphuric acid, 2-8 min, at 4°C (5)
Removal of seed covering structures: slit seed coat (5)
B. oleracea var gemnifera
Pre-dry: room temperature, 1w (54)
B. rapa
Constant temperatures: 20°C in light (33); 20°C in dark (44)
Alternating temperatures: 20°/30°C, 15°/20°C, 5°/20°C in light (33)
Potassium nitrate: co-applied, 0.2%, at 20°/30°C (16h/8h) in light (33); co-applied, 0.2%, plus pre-chill, 10°C, 3d, germinate at 20°/30°C (16h/8h) in light (33)
Thiourea: pre-applied, 1,5h, 1, 5% (33)
Benzyladenine: co-applied, 100 ppm (33)
GA3: co-applied, 1000 ppm (33)
GA7: co-applied, 50, 200 ppm (33)
Light: daylight (8,33)
B. tournefortii
Light: dark (40)
V. Successful dormancy-breaking treatments
B. alba
Constant temperatures: 5°-25°C (52); 17°C in continuous light, 1.5x10-4 mol m-2 s-1 (26); 26°C in light, 1.5-6x10-5 mol m-2 s-1 (26); 26°C, dark (26)
Alternating temperatures: 18°/36°C, 10°/36°C in light (8)
GA3: co-applied, 100 ppm (40)
Potassium nitrate: co-applied, 0.2%, at 20°/30°C in light (52)
Removal of seed covering structures: testa (21,22)
B. campestris
Alternating temperatures: 20°/30°C (16h/8h) in dark (38,39)
Potassium nitrate: co-applied, 0.2%, at 20°/30°C (16h/8h) in light (52)
B. chinensis var pekinensis
Pre-chill (ISTA)
B. juncea
Pre-chill, Potassium nitrate (ISTA)
Light, Pre-chill, Potassium nitrate (AOSA)
Constant temperatures: 15°C in red light (27); 5°-15°C (52)
Alternating temperatures: 15°/25°C (16h/8h) (52)
GA3: co-applied, 100 ppm, at 20°C in dark (30); co-applied, 50, 100 ppm, plus thiourea, 0.5% (30); co-applied, 50, 100 ppm, plus thiourea, 0.5%, then pre-chill, 3°-5°C, 2d (30); co-applied, 50, 100 ppm, then pre-chill, 2°-5°C, 2d (30)
Thiourea: co-applied, 0.5%, at 20°C in light (30); co-applied, 0.5%, then pre-chill, 3°-5°C, 2d (30)
Removal of seed covering structures: then pre-wash, 17h (45)
Potassium nitrate: co-applied, 0.2%, at 20°/30°C (16h/8h) in light (25,52)
B. juncea var crispifolia
Constant temperatures: 15°C (49)
B. kaber
Constant temperatures: 15°C in light (3); 17°C (53)
Alternating temperatures: 20°/30°C (16h/8h) (39)
Pre-chill: 7°C, 8d (53)
GA3: co-applied, 10-3 M (12); co-applied, 100 ppm (40); co-applied, 500 ppm (27); co-applied, 500, 1000 ppm (55); co-applied, 5x10-4 M, at 10°/30°C (16h/8h) (16); pre-applied, 24h, 500 ppm (4); pre-applied, 24h, 1000-5000 ppm (6); pre-applied, 24h, 2000 ppm (55); pre-applied, 12-24h, 2000 ppm (6)
Sucrose: pre-applied, 24h, 2%, plus GA3, 5, 10 ppm (6)
Removal of seed covering structures: excise embryo (6)
Sodium hypochlorite: pre-applied, 30,60 min, 6%, germinate at 10°/30°C (16h/8h) in dark (16); pre-applied, 15-60 min, 6%, germinate at 10°/30°C (16h/8h) in light (16); pre-applied, 15-120 min, 6%, plus GA3, co-applied, 5x10-4 M, at 10°/30°C (16h/8h) in light or dark (16)
B. napella
Alternating temperatures: room temperature/32°C (41)
B. napus
Pre-chill (ISTA)
Constant temperatures: 15°C (49)
Thiourea: co-applied, 0.5-1% (14)
Urea: co-applied, 0.01-0.1% (14)
B. napus var napobrassica
Pre-chill (ISTA)
Alternating temperatures: 18°/36°C, 10°/36°C (16h/8h) in light (8)
B. nigra
Pre-chill, Potassium nitrate (ISTA)
Light, Potassium nitrate, Pre-chill (AOSA)
Constant temperatures: 15°C (49); 6°-15°C (35)
Alternating temperatures: 18°/36°C, 10°/36°C (16h/8h) in light (8); 20°/30°C in light (16h/8h) (52); 20°/30°C (16h/8h) (39,44)
Pre-chill: 6°C, 3-5d (35)
Pre-dry: 30°C, 2-5d (35)
Pre-soak: 6h, 20°C (44)
GA3: co-applied, 100 ppm (40)
Potassium nitrate: co-applied, 0.2%, at 20°/30°C (16h/8h) in light (25,52)
B. oleracea
Pre-chill, Potassium nitrate (ISTA)
Alternating temperatures: 18°/36°C, 10°/36°C (16h/8h) in light (8); 20°/30°C (16h/8h) (18)
B. oleracea var acephala
Light, Pre-chill, Potassium nitrate (AOSA)
Alternating temperatures: 20°/30°C (16h/8h) in light (44)
B. oleracea var alboglabra, B. oleraceae var botrytis
Light, Pre-chill, Potassium nitrate (AOSA)
B. oleracea var capitata
Light, Pre-chill, Potassium nitrate (AOSA)
Thiourea: co-applied, 0.5%, at 20°C in light (30); co-applied, 0.5%, plus pre-chill, 3°-5°C, 2d (30)
GA3: co-applied, 50, 100 ppm (30); co-applied, 50, 100 ppm, plus thiourea, 0.5% (30); co-applied, 50, 100 ppm, plus pre-chill, 3°-5°C, 2d (30); co-applied, 50, 100 ppm, plus thiourea, 0.5%, then pre-chill, 3°-5°C, 2d (30)
Scarification: concentrated sulphuric acid, 1 min, at 4°C, germinate at 30°C (5)
Removal of seed covering structures: (5)
B. oleracea var gemnifera
Light, Pre-chill, Potassium nitrate (AOSA)
Pre-dry: room temperature, 3w (54)
Removal of seed covering structures: excise embryo (54)
B. oleracea var gongylodes, B. oleracea var tronchuda
Light, Pre-chill, Potassium nitrate (AOSA)
B. perviridis
Pre-chill (ISTA)
B. rapa
Pre-chill, Potassium nitrate (ISTA)
Light, Potassium nitrate (AOSA)
Constant temperatures: 20°C in light (44)
Alternating temperatures: 18°/36°C, 10°/36°C (16h/8h) in light (8); 20°/30°C (16h/8h) in light (44)
GA3: co-applied, 400 ppm (33)
B. spinescens, B. tournefortii, B. vesicaria
GA3: co-applied, 100 ppm (40)
VI. Comment
In general seeds of Brassica spp. require light and alternating temperature regimes for the promotion of germination. The following alternating temperature regimes are likely to be more effective in promoting germination than the standard regime of 20°/30°C: 10°/30°C (7,16); 10°/36°C (8); 15°/25°C (23). If constant germination test temperatures have to be used then the range 10°-15°C, in light, is preferable to higher temperatures. Pre-chill treatments appear to produce somewhat erratic results and are probably better avoided.
Although potassium nitrate is recommended by ISTA and AOSA for breaking dormancy in many Brassica spp., gibberellins are more effective (A). Although ISTA/AOSA prescriptions and recommendations are reasonably effective, with particularly dormant accessions, however, standard treatments such as 20°/30°C (16h/8h) in light with potassium nitrate, co-applied, 0.2%, are not entirely effective. As an alternative test at 10°/30°C or 15°/25°C (16h/8h) in light, with GA3, co-applied at 100, 200 ppm - or possibly higher.
VII. References
1. Bartley, M.R. and Frankland, B. (1982). Analysis of the dual role of phytochrome in the photoinhibition of seed germination. Nature, 300, 750-752.
2. Bierhuizen, J.F. and Wagenvoort, W.A. (1974). Some aspects of seed germination in vegetables. 1. The determination and application of heat sums and minimum temperature for germination. Scientia Horticulturae, 2, 213-219.
3. Chakrabarti, A.G. (1977). Effects of temperature shift on weed seed germination. Castanea, 42, 279-285.
4. Corns, W.G. (1960). Effects of gibberellin treatment on germination of various species of weed seeds. Canadian Journal of Plant Science, 40, 47-51.
5. Cox, L.G., Munger, H.M. and Smith, E.A. (1945). A germination inhibitor in the seed coats of certain varieties of cabbage. Plant Physiology, 20, 289-294.
6. Edwards, M.M. (1968). Dormancy in seeds of charlock. II. The influence of the seed coat. Journal of Experimental Botany, 19, 583-600.
7. Frank, W.J. and Wieringa, G. (1928). Artificial drying and low temperature as means employed in obtaining an increase in germination of some vegetable seeds. Proceedings of the Association of Official Seed Analysts, 19, 24-27.
8. Gadd, I. (1939). On methods for the elimination of seed dormancy in seed control work. Proceedings of the International Seed Testing Association, 11, 96-118.
9. Gugnani, D., Banerjee, S.K. and Singh, D. (1975). Germination capacity in relation to seed coat colour in cabbage and mustard. Seed Science and Technology, 2, 575-579.
10. Harrington, J.F. (1963). The effect of temperature on the germination of several kinds of vegetable seeds. Proceedings of the 16th International Horticulture Congress, 2, 435-441.
11. Holm, R.E. (1972). Volatile metabolites controlling germination in buried weed seeds. Plant Physiology, 50, 293-297.
12. Holm, R.E. and Miller, M.R. (1972). Weed seed germination responses to chemical and physical treatments. Weed Science, 20, 150-153.
13. Holm, R.E. and Miller, M.R. (1972). Hormonal control of weed seed germination. Weed Science, 20, 209-212.
14. Hori, Y. and Sugiyama, T. (1954). [Dormancy of the seeds of leaf mustards. II.] Journal of the Horticultural Association of Japan, 22, 223-229. (Cited by Takahashi and Suzuki (1980).)
15. Horvath, G., Balla, I. and Nagy, L. (1981). Some environmental factors effecting the germination of Brassicas. Kertgazdasag, 5, 79-85.
16. Hsiao, A.I. (1980). The effect of sodium hypochlorite, gibberellic acid and light on seed dormancy and germination of stink weed and wild mustard. Canadian Journal of Plant Science, 60, 643-649.
17. Jennings, R.W., Collins, H.A., Bettis, R.B. and Biswas, P.K. (1968). Effects of several chemical stimulants and inhibitors on seed germination and oxygen consumption of selected weed species. Abstracts of the 1968 Meeting of the Weed Science Society of America, 23-24.
18. Johnston, M.E.H. and Miller, J.G. (1963). Optimum germination conditions for some species of the genus Brassica. Proceedings of the International Seed Testing Association, 28, 39-44.
19. Kidd, F. (1914). The controlling influence of carbon dioxide in the maturation, dormancy and germination of seeds. - Part I. Proceedings of the Royal Society, Series B, 87, 408-421.
20. Kidd, F. (1914). The controlling influence of carbon dioxide in the maturation, dormancy and germination of seeds. - Part II. Proceedings of the Royal Society, Series B, 87, 609-625.
21. Kidd, F. and West, C. (1917). The controlling influence of carbon dioxide. IV. On the production of secondary dormancy in seeds of Brassica alba following treatment with carbon dioxide, and the relation of this phenomenon to the question of stimuli in growth processes. Annals of Botany, 31, 457-487.
22. Kidd, F. and West, C. (1920). The role of the seed-coat in relation to germination of immature seed. Annals of Botany, 34, 440-446.
23. Klitgard, K. (1972). Report of the working group on the germination of Beta. Brassica and Allium. Proceedings of the International Seed Testing Association, 37, 365-375.
24. Kotowski, F. (1926). Temperature relations to germination of vegetable seeds. Proceedings of the American Society for Horticultural Science, 23, 176-186.
25. Lewis, N.G. (1942). Dormancy in cultivated mustard and the use of potassium nitrate. Proceedings of the Association of Official Seed Analysts, 34, 17-18.
26. MacDonald, I.R. and Hart, J.W. (1981). An inhibitory effect of light on the germination of mustard seed. Annals of Botany, 47, 275-277.
27. Mayer, A.M. and Poljakoff-Mayber, A. (1963). The germination of seeds. Pergamon Press.
28. 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.
29. Nakamura, S., Okasako, Y. and Yamada, Y. (1955). [Effect of light on the germination of vegetable seeds.] Journal of the Horticultural Association of Japan, 24, 17-28.
30. Nakamura, S., Watanabe, S. and Ichihara, J. (1960). Effects of gibberellin on the germination of agricultural seeds. Proceedings of the International Seed Testing Association, 25, 433-439.
31. Nutile, G.E. (1952). Persistence of dormancy in seed of some cultivated Brassica. Newsletter of the Association of Official Seed Analysts, 26, 6-8.
32. Povilaitis, B. (1956). Dormancy studies with seeds of various weed species. Proceedings of the International Seed Testing Association, 21, 88-111.
33. Renard, H.A. and Clerc, P. (1978). Levée de dormance par les gibberellines chez quatre espèces Impatiens balsamina, Lavandula angustifolia, Brassica rapa et Viola odorata. Seed Science and Technology, 6, 661-677.
34. 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 Shams University, 818, 30 pp.
35. Shuck, A.L. (1936). A preliminary report on the germination of mustard seed. Proceedings of the Association of Official Seed Analysts, 28, 74-76.
36. Singh, R.D., Tiwari, S.N. and Lal, S.D. (1975). Studies on the temperature and media relations to germination of vegetable seeds. I. Knol Kohl (B. oleracea L. var. caulorapa) and Capsicum (C. annuum L.). Progressive Horticulture, 7, 47-50.
37. Steinbauer, G.P. (1942). Use of potassium nitrate in overcoming dormancy of seed of cultivated mustard. Newsletter of the Association of Official Seed Analysts, 16, 19.
38. Steinbauer, G.P. and Frank, P. (1954). Primary dormancy and germination requirements of seeds of certain Cruciferae. Proceedings of the Association of Official Seed Analysts, 44, 176-181.
39. Steinbauer, G.P., Grigsby, B., Correa, L. and Frank P. (1955). A study of methods for obtaining laboratory germination of certain weed seeds. Proceedings of the Association of Official Seed Analysts, 45, 48-51.
40. Takahashi, N. and Suzuki, Y. (1980). Dormancy and seed germination. In Brassica Crops and wild allies (eds. S. Tsunoda, K. Hinata and C. Gomez-Campo), pp. 323-337. Japan Scientific Societies Press, Tokyo.
41. Takiguti, Y. (1930). [On the germination of Brassica napella seed.] Scientific Bulletin, Faculty of Agriculture, Kyushu Imperial University, 4, 22-36.
42. Taylorson, R.B. (1979). Response of weed seeds to ethylene and related hydrocarbons. Weed Science, 27, 7-10.
43. Thompson, P.A. (1972). Geographical adaptation of seeds. In Seed Ecology (ed. W. Heydecker), pp. 31-58. Butterworths, London.
44. Thurlimann, L. (1928). Germination of Brassicas (vegetable). Proceedings of the Association of Official Seed Analysts, 19, 71-74.
45. Tokumasu, S. (1970). Prolongation of seed dormancy by dry storage in Brassica japonica Sieb. Journal of the Japanese Society of Horticultural Science, 39, 169-177.
46. Tokumasu, S. (1971). Effect of dry and wet storage upon seed dormancy in Cruciferous vegetables. Journal of the Japanese Society of Horticultural Science, 40, 23-28.
47. Tokumasu, S. (1975). Prolonged dormancy in the seeds preserved in harvested fruit of Brassica vegetables. Scientia Horticulturae, 3, 267-273.
48. Tokumasu, S. (1977). Seasonal periodicity of the loss of dormancy of imbibed seeds in Brassica vegetables. Scientia Horticulturae, 6, 101-106.
49. Tokumasu, S., Kamei, S. and Kato, M. (1981). [Effects of storage humidity and germination temperature on germination percentage of Brassica seed.] Japanese Journal of Breeding, 31, 109-120. (From Seed Abstracts, 1982, 5, 1595.)
50. Tokumasu, S., Kato, M. and Yano, F. (1975). [The dormancy of seed as affected by different humidities during storage in Brassica.] Japanese Journal of Breeding, 25, 197-202.
51. Toole, E.H. (1961). The effect of light and other variables on the control of seed germination. Proceedings of the International Seed Testing Association, 26, 659-673.
52. Toole, E.H. and Toole, V.K. (1939). Germination of some Brassica types at different temperatures. Proceedings of the International Seed Testing Association, 11, 51-56.
53. Went, F.W. (1961). Problems in seed viability and germination. Proceedings of the International Seed Testing Association, 26, 674-685.
54. Wilmar, J.C. and Hellendoorn, M. (1968). Embryo culture of brussels sprout for breeding. Euphytica, 17, 28-37.
55. Witcombe, J.R. and Whittington, W.J. (1972). The effects of selection for reduced dormancy in charlock (Sinapis arvensis). Heredity, 29, 37-49.
CRAMBE
|
C. abyssinica Hochst. ex R.E. Fries |
crambe |
|
C. cordifolia Steven |
|
I. Evidence of dormancy
Crambe seeds (C. abyssinica) can show slight dormancy (1), but seeds of C. cordifolia can show considerable dormancy, requiring, for example, more than 2 years after-ripening for dormancy to be lost (7).
II. Germination regimes for non-dormant seeds
C. abyssinica
Constant temperatures: 25°C in dark (6)
III. Unsuccessful dormancy-breaking treatments
C. abyssinica
Alternating temperatures: 20°/30°C (16h/8h) (2)
Pre-chill: 5°C, 5d (1,3)
Potassium nitrate: co-applied, 0.2% (5,6)
Light: 9h/d (1); 100 fc, 8h/d or continuous, either above 28°C or below 25°C (2,6)
IV. Partly-successful dormancy-breaking treatments
C. abyssinica
Constant temperatures: 15°C in light, with or without potassium nitrate, co-applied, 0.2% (1)
Alternating temperatures: 15°/35°C, 20°/35°C (16h/8h), light, 9h/d, with or without potassium nitrate, co-applied, 0.2% (1); 15°/20°C, 15°/25°C, 15°/30°C, 20°/25°C (16h/8h) in light, 9h/d (1)
Light: 8h/d, at 26°-28°C (2); dark, continuous (2,4,6)
V. Successful dormancy-breaking treatments
C. abyssinica
Constant temperatures: 20°C, 25°C in light, 9h/d (1)
Alternating temperatures: 20°/30°C (16h/8h) in light, 9h/d (1,3)
Potassium nitrate: co-applied, 0.2%, at 15°/20°C, 15°/25°C, 15°/30°C, 20°/30°C (16h/8h) in light, 9h/d (1)
Removal of seed covering structures: dehull, germinate at 20°C, dark (3,4)
C. cordifolia
Pre-chill: 0°-2°C, 30-90d (7)
Removal of seed covering structures: testa, germinate at 20°C, 25°C (7)
VI. Comment
Dormancy, though present, is not a major problem for seeds of C. abyssinica; crambe seeds are able to germinate over a wide range of temperatures (1,2). However, attempts to germinate the seeds under unfavourable conditions can induce abnormal germination. For example, seeds germinated on top of filter papers in light produced abnormal seedlings at an alternating temperature regime of 20°/30°C, and at constant temperatures above 28°C, whereas normal seedlings were produced at a constant temperature of 20°C (6). In contrast seeds germinated between papers at 20°C, 25°C and 20°/30°C gave high, normal germination (6).
Two alternative test procedures are suggested. In both cases test the seeds between papers - for example, as in the rolled paper towel test. One alternative is to test at 20°C in light, 9h/d, with potassium nitrate, co-applied, 0.2% (1). The second alternative is to test at 25°C, dark (6). In addition potassium nitrate, co-applied, 0.2%, could be provided as a further stimulus to promote germination in this regime. These treatments are also suggested for seeds of C. cordifolia with the additional treatment of removal of the seed covering structures.
VII. References
1. Bass, L.N., Clark, D.C. and Sayers, R.L. (1965). Germination experiments with crambe seed. Proceedings of the Association of Official Seed Analysts, 55, 47-51.
2. Larsen, A.L. and Skaggs, D.P. (1969). Crambe seed germination response on a thermogradient plate. Proceedings of the Association of Official Seed Analysts, 59, 44-50.
3. Maguire, J.D. and Youngman, V. (1963). Germination of crambe. Newsletter of the Association of Official Seed Analysts, 37, 6-7.
4. Maguire, J.D. and Youngman, V. (1965). Laboratory testing of crambe. Proceedings of the Association of Official Seed Analysts, 55, 169-176.
5. Schroeder, E.M. (1963). Preliminary report on germination tests of Crambe abyssinica. Newsletter of the Association of Official Seed Analysts, 37, 10-11.
6. Skaggs, D.P. and Larsen, A.L. (1969). Recommendation for germination of crambe seed. Proceedings of the Association of Official Seed Analysts, 59, 51-57.
7. Kolomiets, I.A., Parfenova, T.M. and Teplitskaya, E.V. (1968). [The physiology of dormancy and germination of Crambe cordifolia seeds.] Fiziologia Rast, 15, 979-987. (From Horticultural Abstracts, 1969, 39, 1482.)
LEPIDIUM
|
L. campestre (L.) R. Br. |
field cress, field pepperweed |
|
L. densiflorum Schrad. [L. apetalum
L.] |
|
|
L. draba L. |
|
|
L. lasiocarpum Nutt. |
|
|
L. muelleri-ferdinandi Thell. |
|
|
L. perfoliatum L. |
yellowflower pepperweed |
|
L. sativum L. |
garden-cress |
|
L. virginicum L. |
Virginia peppergrass |
I. Evidence of dormancy
Seeds of all Lepidium spp. can show very deep dormancy (1,2,4,9,12,15,17,20,22). After-ripening periods of 3 months for L. campestre and L. sativum (8,9), 4 months for L. perfoliatum (20), 1-2 years for L. lasiocarpum (1) and between 8 months to 3 years for L. virginicum (9) have been reported to be required for dormancy to be lost.
II. Germination regimes for non-dormant seeds
L. muelleri-ferdinandi
Constant temperatures: 16°C (24)
L. sativum
TP: 20°/30°C (16h/8h); 20°C: 10d (ISTA)
TP; BP: 15°C: 10d (AOSA)
III. Unsuccessful dormancy-breaking treatments
L. campestre
Constant temperatures: 20°C, 30°C, light or dark (9)
Alternating temperatures: 20°/30°C (16h/8h), light or dark (9)
Light: dark, continuous, at 25°C, 30°C (9); dark, continuous, at 30°C, 35°C (16); red, 0.3x10-3 W cm-2, 16 min, at 35°C (16)
L. densiflorum
Light: far red (15)
L. lasiocarpum
Constant temperatures: 20°-35°C, diffuse daylight (1,2)
Alternating temperatures: 20°/30°C (16h/8h), diffuse daylight (1,2)
L. perfoliatum
Constant temperatures: 0.5°C, 10°C, 20°C (20)
Alternating temperatures: 0.5°-20°/-20°C (20)
Pre-chill: -20°C, 30,60, 120d (20)
L. sativum
Urea: co-applied, 0.5% (7)
Potassium nitrate: co-applied, 0.3% (7)
Indoleacetic acid: co-applied, 50, 100 ppm (8)
Kinetin: co-applied, 50, 100 ppm (8)
L. virginicum
Pre-chill: 3°-5°C, 7-14d, germinate at 20°/30°C (17h/7h), dark (14)
Warm stratification: 25°C, 2d, dark, germinate at 15°C, dark (12); 15°C, 2d, dark, germinate at 25°C, dark (12); 20°C, 3d, dark, 40°C, 1-4min, red light, germinate at 20°C, dark (11)
Light: dark, continuous, at 15°-35°C (6,12,14,16); dark, at 15°/25°C (2d/2d) (22); dark, continuous, at 20°/30°C (16h/8h) (6,14,16); red, at 30°C, 35°C (6,15,16); red, at 30°C, with potassium nitrate, co-applied, 0.2% (15); far red (12, 15); far red, 180x10-6 W cm-2, 1 min (22)
GA3: co-applied, 10-6-10-4 M (22)
Kinetin: co-applied, 100 ppm (22)
IV. Partly-successful dormancy-breaking treatments
L. campestre
Constant temperatures: 15°-20°C, red light, 0.3x10-3 W cm-2, 16 min (16); 20°C (9)
Alternating temperatures: 20°/30°C (16h/8h) (9); 20°/30°C (16h/8h), red light, 0.3x10-3 W cm-2, 16 min (16)
Potassium nitrate: co-applied, 0.2% (9)
Scarification: concentrated sulphuric acid (9)
Removal of seed covering structures: (9)
L. draba
Constant temperatures: 0.5°-35°C (21)
Alternating temperatures: 20°/30°C, 20°/35°C (16h/8h) (21)
L. lasiocarpum
Constant temperatures: 10°C, 15°C (1,2)
Alternating temperatures: 10°/20°C, 10°/30°C, 15°/30°C (16h/8h) (1,2)
L. perfoliatum
Alternating temperatures: 15°/20°C (16h/8h) (20); 20°/30°C (16h/8h), light or dark (23)
L. sativum
Thiourea: co-applied, 0.2% (7)
GA3: co-applied, 50, 100 ppm (8)
L. virginicum
Alternating temperatures: 20°/30°C (16h/8h), light, 50 fc (9)
Light: red, continuous, at 15°C, 20°C, 25°C, 20°/30°C (16h/8h) (6); red, 0.3x10-3 W cm-2, 16 min, at 15°C, 25°C (12); red, 0.3x10-3 W cm-2, 16 min, at 15°-25°C, 20°/30°C (15, 16); dark, 2d, at 25°C, germinate at 15°C, red, 0.3x10-3 W cm-2, 16 min (12); dark, 1d, at 20°C, then red, 10-20s before or after 35°C, 2h (12); dark, 3d, at 20°C, 25°C, 30°C, 50°C, 64 min, red (11); dark, 2d, at 25°C, then red, 1h, 1 J cm-2, germinate at 15°C, dark (15)
Potassium nitrate: co-applied, 0.2% (9,13)
Thiourea: co-applied (13)
Coumarin: co-applied, 2x10-5 M (15)
Scarification: concentrated sulphuric acid (9)
Removal of seed covering structures: (9)
V. Successful dormancy-breaking treatments
L. campestre
Constant temperatures: 15°C, light, 50 fc (10)
Alternating temperatures: 15°/30°C, light, 50 fc (10)
L. perfoliatum
Constant temperatures: 5°C (20); 15°C, 20°C, dark (23)
L. sativum
Pre-chill (ISTA)
Light (AOSA)
Constant temperatures: 3°-17°C, light, 8h (3,19)
Alternating temperatures: 10°/36°C (16h/8h) (4)
Pre-soak: (18)
L. virginicum
Alternating temperatures: 20°/30°C (16h/8h), light (10)
Potassium nitrate: co-applied, 0.2%, at 15°/25°C (16h/8h), light (5,15,16); co-applied, 0.2%, at 20°/30°C (17h/7h), light (14)
GA3: co-applied, 2.5x10-3 M (13,17); co-applied, 10-3 M, at 15°/25°C (2d/2d) (22)
Light: dark, 3d, at 20°C, then 40°C, 32-64 min, then red, 0.4x10-7 mol cm-2, 16 min (11); dark, 2d, at 15°C, red, 1 J cm-2, 1h, germinate at 25°C (15); dark, 1,2d, at 15°C, then red, 0.3x10-3 W cm-2, 16 min, germinate at 25°C (12); dark, 1d, at 20°C, then red, 0.3x10-3 W cm-2, 16 min, then 35°C, dark, 2h, then germinate at 20°C, dark (13); dark, 2d, at 15°C, then red, 18x10-5 W cm-2, 1s, germinate at 25°C, dark (22)
VI. Comment
Successful germination of seeds of Lepidium spp. requires light (5,6,11-16,22), low constant temperatures - viz. 5°C for L. perfoliatum (20), 10°-15°C for the other species (1,2,3,10,19) - or alternating temperatures - viz. 10°/30°C (1,2), 10°/36°C (4), 15°/25°C (5,15,16), or 15°/30°C (10). The alternating temperature regime prescribed by ISTA (20°/30°C) is probably less effective than these four alternating temperature regimes in promoting the germination of dormant seeds (1,2,16).
When combined with a suitable alternating temperature regime, potassium nitrate is quite effective in promoting germination (5,13-16). It is therefore suggested that the seeds be tested for germination at alternating temperature regimes of 10°/30°C, 15°/25°C, or 15°/30°C (16h/8h) in diffuse light (see Chapter 6) with 0.2% potassium nitrate co-applied.
VII. References
1. Barton, L.V. (1936). Germination of some desert seeds. Contributions from the Boyce Thompson Institute, 8, 7-11.
2. Barton, L.V. and Crocker, W. (1948). Twenty years of seed research at Boyce Thompson Institute for plant research. Faber and Faber, London.
3. Bierhuizen, J.F. and Wagenvoort, W.A. (1974). Some aspects of seed germination in vegetables. 1. The determination and application of heat sums and minimum temperature for germination. Scientia Horticulturae, 2, 213-219.
4. Gadd, I. (1939). On methods for the elimination of seed dormancy in seed control work. Proceedings of the International Seed Testing Association, 11, 96-118.
5. Hendricks, S.B., Borthwick, H.A. and Downs, R.J. (1956). Pigment conversion in the formative responses of plants to radiation. Proceedings of the National Academy of Sciences of the USA, 42, 19-26.
6. Mayer, A.M. and Poljakoff-Mayber (1963). The germination of seeds. Pergamon Press.
7. 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.
8. 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 Shams University, 818, 30 pp.
9. Steinbauer, G.P. and Frank, P. (1954). Primary dormancy and germination requirements of seeds of certain Cruciferae. Proceedings of th e Association of Official Seed Analysts, 44, 176-181.
10. Steinbauer, G.P., Grigsby, B., Correa, L. and Frank, P. (1955). A study of methods for obtaining laboratory germination of certain weed seeds. Proceedings of the Association of Official Seed Analysts, 45, 48-52.
11. Taylorson, R.B. and Hendricks, S.B. (1972). Interactions of light and a temperature shift on seed germination. Plant Physiology, 49, 127-130.
12. Toole, E.H. (1959). Effect of light on the germination of seeds. In Photoperiodism and Related Phenomena in Plants and Animals (ed. R.B. Withrow), pp. 89-99. American Association for the Advancement of Science, Washington, Publication No. 55.
13. Toole, E.H. (1961). The effect of light and other variables on the control of seed germination. Proceedings of the International Seed Testing Association, 26, 659-673.
14. Toole, E.H. and Toole, V.K. (1940). Note on the germination of seeds of Barbarea verna and Lepidium virginicum. Proceedings of the International Seed Testing Association, 12, 32-38.
15. Toole, E.H., Toole, V.K., Borthwick, H.A. and Hendricks, S.B. (1955). Photocontrol of Lepidium seed germination. Plant Physiology, 30, 15-21.
16. Toole, E.H., Toole, V.K., Borthwick, H.A. and Hendricks, S.B. (1955). Interaction of temperature and light in germination of seeds. Plant Physiology, 30, 473-478.
17. Toole, V.K. and Cathey, H.M. (1961). Responses to gibberellin of light-requiring seeds of lettuce and Lepidium virginicum. Plant Physiology, 36, 663-671.
18. Trotter, W.R. (1949). Effect of thiouracil and uracil on the germination of cress seeds. Nature, 164, 63.
19. Wagenvoort, W.A. and Bierhuizen, J.F. (1977). Some aspects of seed germination in vegetables: II. The effect of temperature fluctuation, depth of sowing, seed size and cultivar, on heat sum and minimum temperature for germination. Scientia Horticulturae, 6, 259-270.
20. Young, J.A., Evans, R.A., Gifford, R.O. and Eckert, R.E. Jr. (1970). Germination of three species of Cruciferae. Weed Science, 18, 41-48.
21. Brown, E.O. and Porter, R.H. (1942). The viability and germination of seeds of Convolvulus arvensis L. and other perennial weeds. Iowa Agricultural Experiment Station, Research Bulletin No. 294, 475-504.
22. Evans, R.O. and Fratianne, D.G. (1977). Interactions of applied hormones in the germination of Lepidium virginicum seeds. Ohio l of Science, 77, 236-239.
23. Maguire, J.D. and Overland, A. (1959). Laboratory germination of seeds of weedy and native plants. Washington Agricultural Experiment Station, Circular No. 349.
24. Ross, M.A. (1976). The effects of temperature on germination and early growth of three plant species indigenous to Central Australia. Australian Journal of Ecology, 1, 259-263.
NASTURTIUM
|
N. microphyllum (Boenn.) Reichb. [N. uniseriatum
Howard & Manton; Rorippa microphylla (Boenn.) Hyl.] |
brown watercress |
|
N. officinale R. Br. [Rorippa
Nasturtium-aquaticum (L.) Hayek; Sisymbrium Nasturtium-aquaticum
L.; Radicula Nasturtium-aquaticum Britt. & Rendle] |
green watercress |
|
N. palustre DC. [N. islandica; Rorippa
islandica (Oeder) Borb.] |
marsh cress |
I. Evidence of dormancy
The above Nasturtium [Rorippa] spp. show considerable seed dormancy (1-5,7-9,11,12). After-ripening periods are reported to vary from 2 (1) to 8 months (11) at room temperature and 8 months in soil (9). Seeds of N. microphyllum are reported to be more dormant than seeds of N. officinale (8).
II. Germination regimes for non-dormant seeds
N. officinale
BP; TP: 20°/30°C (16h/8h): 14d (ISTA)
TP: 20°/30°C (16h/8h): 14d (AOSA)
III. Unsuccessful dormancy-breaking treatments
N. microphyllum
Light: dark (8,9)
Removal of seed covering structures: prick, test in dark (8)
N. officinale
Constant temperatures: 20°C (5)
Light: continuous, at 25°C (2); at 15°C (3); far red, 10 min (2); dark (3)
GA4/7: co-applied, 10-6, 10-5 M, at 20°C in dark (2)
Cytokinin: co-applied, 10-4 -10-7 M, at 20°C in dark (2)
N. palustre
Constant temperatures: 23°C in light or dark (7); 20°C, 25°C, 35°C, daylight, 50 fc (11); 20°C, 25°C, dark, 233d (13)
IV. Partly-successful dormancy-breaking treatments
N. microphyllum
Light: dark, 1-4d, then 5 min light (8); continuous daylight (8,9) Removal of seed covering structures: prick, test in light (8)
N. officinale
Constant temperatures: 5°-30°C, daylight (10)
Alternating temperatures: 10°/22°C, 10°/27°C, 10°/32°C, 10°/38°C, 15°/27°C, 15°/32°C, 15°/38°C, 22°/32°C, 22°/38°C (18h/6h) in daylight (10)
Light: continuous, at 20°C (2); red, 10 min, at 15°C (2)
GA4/7: co-applied, 10-3, 10-4 M, at 20°C, dark (2); co-applied, 10-4 M, plus cytokinin, co-applied, 10-4 -10-7 M, at 20°C, dark (2); co-applied, 10-5 M, plus cytokinin, co-applied, 10-6, 10-7 M, at 20°C, dark (2)
Hydrogen peroxide: co-applied, 0.25, 0.6% (6)
N. palustre
Alternating temperatures: 20°/30°C (16h/8h), light, 50 fc (11)
Light: dark, at 23°C, 5d, plus GA3, pre-applied, 24,48h, 5-100 ppm, then light, 1500 lux (7); dark, at 23°C, 1-7d, then light, 24h, 1500 lux, then dark, at 5°C, 24h, germinate at 23°C in light, 1500 lux (7); dark, at 23°C, 5d, then light, 48,72h, 1500 lux, then dark, at 5°C, 6,12h, germinate at 23°C in light, 1500 lux (7); dark, at 23°C, 5d, then light, 6,12h, 1500 lux, then dark, at 5°C, 6-24h, germinate at 23°C in light, 1500 lux (7)
Potassium nitrate: co-applied, 0.2% (11)
V. Successful dormancy-breaking treatments
N. microphyllum
Light: continuous, 28d (8); dark, 3d, then daylight, 5 min, then dark, 11d, then daylight, 5 min, then dark, 14d (8)
N. officinale
Light (AOSA)
Constant temperatures: 10°C, 15°C, continuous light (2)
Warm stratification: 35°C, light or dark, 28d, germinate at 20°C in light (4)
GA4/7: co-applied, 10-5 M, plus cytokinin, co-applied, 10-4, 10-5 M (2,3)
Pre-dry: 40°C, 2-3d (2,3)
N. palustre
Light: dark, at 23°C, 5d, then light, 24h, 1500 lux, then dark, 6-24h, at 5°C, germinate at 23°C in light, 1500 lux (7)
VI. Comment
Light is an essential requirement for the promotion of germination in dormant seeds of Nasturtium spp. (2-4,7-9). Alternating temperatures are more likely to promote germination than constant temperatures (10,14); a regime of 10°/27°±5°C (18h/6h) has been reported to be better than either 15°/32°C or 22°/32°C (10), suggesting that the former regime or that of 10°/30°C (16h/8h) previously, but no longer, prescribed by ISTA should be used in preference to the 20°/30°C (16h/8h) regime currently prescribed by AOSA and ISTA. Treatment with gibberellin or gibberellin plus cytokinin co-applied (2) in addition to light and the above alternating temperature environment are likely to be satisfactory in promoting the germination of most dormant seeds.
VII. References
1. Austin, R.B. (1966). The growth of watercress (Rorippa nasturtium - aquaticum (L.) Hayek) from seed as affected by the phosphorus nutrition of the parent plant. Plant and Soil, 24, 113-120.
2. Biddington, N.L. and Ling, B. (1983). The germination of watercress (Rorippa nasturtium - aquaticum) seeds. I. The effect of age, storage, temperature, light and hormones on germination. Journal of Horticultural Science, 58, 417-426.
3. Biddington, N.L., Ling, B. and Dearman, A.S. (1982). Dormancy and viability of watercress seeds. National Vegetable Research Station, Wellesbourne, Annual Report, 1981, 32, 97.
4. Biddington, N.L., Ling, B. and Dearman, A.S. (1983). The germination of watercress (Rorippa nasturtium - aquaticum) seeds. II. The relationship between seed colour and germination. Journal of Horticultural Science, 58, 27-433.
5. Bleasdale, J.K.A. (1958). The propagation of watercress from seed. National Vegetable Research Station, Wellesbourne, Annual Report, 1957, 8, 35.
6. Demoussy, E. (1916). Influence de l'eau oxygénée sur la germination. Comptes Rendus de l'Académie des Sciences (Paris), 162, 435-438.
7. Fujii, T. and Isikawa, S. (1961). Successive processes involved in the germination response of Nasturtium seed. Plant and Cell Physiology, 1, 77-86.
8. Howard, H.W. and Lyon, A.G. (1951). Effect of light on the germination of watercress seeds. Nature, 168, 253-254.
9. Howard, H.W. and Lyon, A.G. (1952). Biological flora of the British Isles, Nasturtium R.Br., Nasturtium officinale R.Br. (Rorippa nasturtium-aquaticum (L.) Hayek). Journal of Ecology, 40, 228-245.
10. Morinaga, T. (1926). Germination of seeds under water. American Journal of Botany, 13, 126-140.
11. Steinbauer, G.P. and Frank, P. (1954). Primary dormancy and germination requirements of seeds of certain Cruciferae. Proceedings of the Association of Official Seed Analysts, 44, 176-181.
12. Watanabe, Y. (1978). [Physiological and ecological studies on upland weeds in Hokkaido.] Research Bulletin of the Hokkaido National Agricultural Experiment Station, 123, 17-77.
13. Mitchell, E. (1926). Germination of seeds of plants native to Dutchess County, New York. Botanical Gazette, 81, 108-112.
14. Thompson, K. and Grime, J.P. (1983). A comparative study of germination responses to diurnally-fluctuating temperatures. Journal of Applied Ecology, 20, 141-156.
RAPHANUS
|
R. sativus L. [R. Raphanistrum L.] |
radish |
I. Evidence of dormancy
Freshly harvested seeds of cultivated varieties of radish can show dormancy (21). Dry storage for 6 weeks, at room temperature, is required to completely remove dormancy (21). Wild types' seeds can show deep dormancy (10, 12) and require 6 months storage, at 20°C, for dormancy to be lost (10,16).
II. Germination regimes for non-dormant seeds
TP; BP: 20°/30°C (16h/8h); 20°C: 10d (ISTA)
BP: 20°C: 6d (AOSA)
Constant temperatures: 3°-17°C (2); 21°C, dark (1); 23°C, dark (5); 11°-30°C (6); 20°C, light, 16h (23)
III. Unsuccessful dormancy-breaking treatments
Pre-chill: 4°C, 3-18w (10)
Warm stratification: 20°C, 6d, with potassium nitrate, co-applied, 2%, then pre-dry, 20°C, 2d (22)
Wet/dry: 1d/2d, 3 cycles, at 20°C (22)
Abscisic acid: pre-applied, 1h, 4x10-5 M (7)
Mannitol: co-applied, 0.4, 0.5 M (9)
Ethanol: co-applied, 0.5% (1); co-applied, 0.1-3% (20)
Coumarin: co-applied, 10-3 M (1)
Sorbic acid: pre-applied, 24h, 0.04-0. 16% (13)
Light: 3h/d - continuous, 200 lux (5); continuous, at 22°C, 32°C (9); 8h/d, 150 fc (10); continuous fluorescent light at low temperatures (11); 20 fc, at 25°C (14); red (19); far red (19); blue (19)
IV. Partly-successful dormancy-breaking treatments
Constant temperatures: 5°-35°C (12)
Alternating temperatures: 5°/15°C, 5°/25°C, 5°/35°C, 15°/25°C, 15°/35°C, 25°/35°C (18h/6h), light, 12h/d (12); 5°/15°C, 10°/20°C, 15°/25°C, 20°/30°C (10); 20°/30°C (16h/8h) (16)
Pre-chill: 5°C, 1-4w, in light (12)
Light: dark (9,14,19); daylight, 12h/d (12); incandescent light (19)
GA3: pre-applied, 1h, 3x10-4 M (7)
N-6-Benzyladenine: pre-applied, 1h, 10-4 M (7)
Indoleacetic acid: co-applied, 10-7 -10-9 M (8)
Sorbic acid: pre-applied, 24h, 0.0025-0.01% (13)
Naphthaleneacetic acid: pre-applied, 10, 20 ppm (15)
Potassium nitrate: pre-applied, 5x10-3-2x10-2 M (18); co-applied, 0.2% (16)
Removal of seed covering structures: (12,16)
Pre-wash: 21°C, 8-24h, germinate at 5°/15°C, 15°/25°C, 20°/30°C (10)
V. Successful dormancy-breaking treatments
Pre-chill (ISTA)
Constant temperatures: 15°-17°C (3)
Alternating temperatures: 10°/30°C (3); 18°/36°C in light (4); 20°/30°C (16h/8h) in light (17)
Fusicoccin: pre-applied, 1h, 1.5x10-5 M, germinate at 25°C, dark (7)
Pre-wash: 21°C, 8,24h, germinate at 10°/20°C (10)
VI. Comment
Alternating temperature regimes are required to break radish seed dormancy (3,10,12); alternations of 5°/15°C or 10°/20°C (10) or 5°/25°C (18h/6h) (12) are more effective than the regime 20°/30°C prescribed by the ISTA. Testing in the dark (9,14,19) is promotory. Pre-chill treatments are unsuccessful for very dormant seeds (10,12), whereas gibberellin and fusicoccin are successful in promoting germination for the very dormant seeds (7). It is suggested that the seeds be tested for germination in an alternating temperature regime of 10°/30°C or 10°/20°C (16h/8h) either in dark or in the light regime given in Chapter 6 with 100 ppm GA3 either co-applied or pre-applied for 1 hour.
VII. References
1. Bernhard, R.A. (1959). Some studies of coumarin and coumarin analogues as germination inhibitors of radish seeds. Botanical Gazette, 121, 17-21.
2. Bierhuizen, J.F. and Wagenvoort, W.A. (1974). Some aspects of seed germination in vegetables. 1. The determination and application of heat sums and minimum temperature for germination. Scientia Horticulturae, 2, 213-219.
3. Eifrig, H. (1957). [New observations on germination tests with various agricultural and vegetable seeds.] Sonderh. Landw. Forsch., 9, 134-139. (From Horticultural Abstracts, 1957, 27, 2466.)
4. Gadd, I. (1939). On methods for the elimination of seed dormancy in seed control work. Proceedings of the International Seed Testing Association, 11, 96-118.
5. Isikawa, S. (1962). Light sensitivity against the germination. III. Studies on various partial process in light sensitive seeds. Japanese Journal of Botany, 18, 105-132.
6. Kotowski, F. (1926). Temperature relations to germination of vegetable seeds. Proceedings of the American Society for Horticultural Science, 23, 176-186.
7. Lado, P., Rasi-Caldogno, F. and Colombo, R. (1974). Promoting effect of fusicoccin on seed germination. Physiologia Plantarum, 31, 149-152.
8. Landau, N. (1940). The effect of hetero-auxin on the germination of some seeds. Palestine Journal of Botany, 1, 409-412.
9. McDonough, W.T. (1967). Dormant and non-dormant seeds: similar germination responses when osmotically inhibited. Nature, 214, 1147-1148.
10. Mekenian, M.R. and Millemsen, R.W. (1975). Germination characteristics of Raphanus raphanistrum. I. Laboratory studies. Bulletin of the Torrey Botanical Club, 102, 243-252.
11. Nakamura, S., Okasako, Y. and Yamada, T. (1955). [Effect of light on the germination of vegetable seeds.] Journal of the Horticultural Association of Japan, 24, 17-28.
12. Piggin, C.M., Reeves, T.G., Brooke, H.D. and Code, G.R. (1978). Germination of wild radish (Raphanus raphanistrum L.). Proceedings of the 1st Conference of the Council of Australian Weed Science Societies, 233-240.
13. Rubtsova, I.D. (1972). [The effect of sorbic acid on seed germination.] Biologicheskii Sbornik, Tambov, 65-68. (From Horticultural Abstracts, 1974, 44, 2490.)
14. Siegel, S.M. (1950). Effects of exposures of seeds to various physical agents. I. Effects of brief exposures to heat and cold on germination and light-sensitivity. Botanical Gazette, 112, 57-70.
15. Singh, K. and Dohare, S.R. (1964). Pre-sowing treatments with naphthaleneacetic acid in relation to growth and development of radish (Raphanus sativus L.). Punjab Horticulture Journal, 4, 160-164. (From Horticultural Abstracts, 1966, 36, 3063.)
16. Steinbauer, G.P. and Frank, P. (1954). Primary dormancy and germination requirements of seeds of certain Cruciferae. Proceedings of the Association of Official Seed Analysts, 44, 176-181.
17. Steinbauer, G.P., Grigsby, B., Correa, L. and Frank, P. (1955). A study of methods for obtaining laboratory germination of certain weed seeds. Proceedings of the Association of Official Seed Analysts, 45, 48-51.
18. Sugawara, T. (1955). [Influence of nitrate on the germination of seeds under oxygen supply of various concentrations.] Proceedings of the Crop Science Society of Japan, 23, 295-296. (From Horticultural Abstracts, 1956, 26, 3298.)
19. Swarnkar, P.L. and Kumar, A. (1977). Observations on the influence of red, far red and blue light on the germination of seeds of the radish, Raphanus sativus. Comparative Physiology and Ecology, 2, 109-110.
20. Thiess, D.E. and Lichtenthaler, H.K. (1973). [The inhibition of seed germination by lower primary alcohols.] Naturwissenschaften, 60, 302.
21. Tokumasu, S. (1971). Effect of dry and wet storage upon dormancy in Cruciferous vegetables. Journal of the Japanese Society of Horticultural Science, 40, 23-28.
22. Wickham, B.D. and Nichols, M.A. (1976). Germination studies with "hardened" vegetable seed. New Zealand Journal of Experimental Agriculture, 4, 457-461.
23. Williams, J.T. and Hanson, J. (1974). The potential of vigour testing for long-term seed storage. Journal of Horticultural Science, 49, 395-401.
