The Solanaceae comprise more than 2000 species of herbaceous plants - including climbers, shrubs and small trees within about 75 genera which provide edible fruits (e.g. Cyphomandra betacea (Cav.) Sendt., tree tomato), edible tubers (e.g. Solanum tuberosum L., potato), and drugs and narcotics (e.g. Datura spp.). The fruits are berries or capsules and the seeds show orthodox storage behaviour. For example, Atropa belladonna L. and Physalis peruviana L. are maintained in the long-term seed store at the Wakehurst Place Gene Bank.
SEED DORMANCY AND GERMINATION
The seeds have a copious endosperm, a curved or annular embryo, and can show considerable dormancy. B.R. Atwater classified seed morphology as endospermic seeds with either axillary linear embryos or axillary miniature embryos (see Table 17.1, Chapter 17). Alternating temperatures, light, gibberellins and potassium nitrate tend to promote seed germination.
Detailed information on seed dormancy and germination is provided in this chapter for the genera Capsicum, Datura, Lycopersicon (including synonyms within Solanum), Nicotiana and Solanum. Recommended germination test procedures and dormancy-breaking treatments for other species are summarised in Table 67.1. In addition the algorithm below may be helpful in developing suitable germination test procedures.
RBG Kew Wakehurst Place algorithm
The first step in the algorithm is to test seeds at constant temperatures of 21°C, 26°C, and 31°C with light applied for 12h/d. If full germination does not occur and a trend in germination response to constant temperatures is observed then test further samples of seeds at more extreme constant temperatures. For example, if a greater proportion of seeds germinate at 21°C than at higher temperatures then test further samples of seeds at constant temperatures of 6°C, 11°C and 16°C with light applied for 12h/d.
If the above constant temperature regimes do not promote full germination then the second step of the algorithm is to test a further sample of seeds in the alternating temperature regime 33°/19°C (12h/12h) with light applied for 12h/d during the period spent at the upper temperature.
If full germination does not occur in the second step of the algorithm then the third step is to test three further samples of seeds at the most appropriate temperature regime determined from a comparison of the results of steps one and two, with GA3 co-applied to the germination test substrates at 3 x 10-4 M, 7 x 10-4 M, and 2.6 x 10-3 M.
If full germination does not occur in the third step of the algorithm then the fourth step is to attempt other GA3 concentrations (e.g. if a trend is apparent in the results of step three then test at more extreme GA3 concentrations) or after-ripen (e.g. expose a sample of the air-dry seeds to the ambient laboratory environment for several weeks).
If full germination has not been promoted, the fifth 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 environment can be obtained from the information provided for five genera in this chapter and from Table 67.1.
TABLE 67.1 Summary of germination test recommendations for species within the Solanaceae
|
Species and Authority |
Substrate |
Temperature |
Duration |
Additional directions |
Source |
|
Atropa belladonna L.
|
TP; BP |
20°/30°C |
28d |
pre-chill |
ISTA |
|
TP |
20°/30°C |
28d |
light, potassium nitrate |
AOSA/Heit |
|
|
Browallia viscosa HBK |
TP; BP |
20°/30°C; 20°C |
21d |
|
ISTA |
|
Browallia spp. |
TP |
20°/30°C |
14d |
light |
AOSA |
|
Cyphomandra betacea (Cav.) Sendt.
|
TP |
25°-30°C |
20d |
light, continuous, pre-chill |
CHML |
|
|
|
21d |
pre-soak, 24h |
Riley |
|
|
Hyoscyamus niger L. |
TP |
20°/30°C |
28d |
light, potassium nitrate |
Heit |
|
Nierembergia hippomanica Miers
|
TP |
20°/30°C; 20°C |
21d |
|
ISTA |
|
|
20°/30°C |
14d |
light, potassium nitrate, 0.2% |
Atwater |
|
|
Nierembergia spp. |
TP |
20°/30°C |
14d |
|
AOSA |
|
Petunia x hybrida Vilm. |
TP |
20°/30°C; 20°C |
14d |
pre-chill, potassium nitrate |
ISTA |
|
TP |
20°/30°C |
10d |
light |
AOSA |
|
|
|
20°/30°C |
14d |
light, potassium nitrate, 0.2% |
Atwater |
|
|
Petunia spp.
|
|
20°/30°C |
14d |
fluorescent light, potassium nitrate, 0.2%, or GA, 400ppm |
Atwater |
|
TP |
20°/30°C |
10d |
potassium nitrate, pre-chill |
AOSA |
|
|
Physalis alkekengi L. |
TP |
20°/30°C |
28d |
light, potassium nitrate, pre-chill |
ISTA |
|
|
20°/30°C |
28d |
light, potassium nitrate, 0.2% |
Atwater |
|
|
Physalis pubescens L. |
TP |
20°/30°C |
28d |
potassium nitrate |
ISTA |
|
TP |
20°/30°C |
28d |
light, potassium nitrate |
AOSA |
|
|
TP |
20°/30°C |
12d |
potassium nitrate |
SGCF |
|
|
Physalis virginianum |
TP |
20°/30C |
12d |
potassium nitrate |
SGCF |
|
Physalis spp. |
TP |
20°/30°C |
24d |
light, potassium nitrate |
AOSA |
|
Salpiglossis sinuata Ruiz & Pav. |
TP; BP |
20°/30°C; 20°C |
21d |
light, pre-chill, potassium nitrate |
ISTA |
|
TP |
20°/30°C |
12d |
potassium nitrate |
AOSA |
|
|
|
20°/30°C |
14d |
light, potassium nitrate, 0.2% |
Atwater |
|
|
Schizanthus pinnatus Ruiz & Pav.
|
TP; BP |
10°C; 15°C |
14d |
pre-chill |
ISTA |
|
|
15°C |
14d |
|
Atwater |
|
|
Schizanthus spp. |
TP |
15°C |
8d |
sensitive to warm temperatures |
AOSA |
CAPSICUM
|
C. annuum L. var abbreviatum Fingerh |
wrinkled peppers |
|
C. annuum L. var acuminatum Fingerh |
chillies |
|
C. annuum L. var cerasiforme (Mill.)
Irish |
cherry peppers |
|
C. annuum L. var conoides (Mill.)
Irish |
cone peppers, tabasco |
|
C. annuum L. var fasciculatum (Sturt.)
Irish |
cluster peppers |
|
C. annuum L. var grossum (L.) Sendt. |
sweet peppers, paprika |
|
C. annuum L. var longum (DC.) Sendt. |
long pepper |
|
C. annuum L. var minimum |
|
|
C. baccatum (L.) Irish |
cherry capsicum |
|
C. chacoense Hunz. |
|
|
C. chinense Jacq. |
|
|
C. frutescens L. [C. minimum Roxb.] |
bird chillies |
|
C. microcarpum DC. |
|
|
C. pubescens Rucz & Pav. |
|
I. Evidence of dormancy
Freshly harvested seeds of C. annuum, C. frutescens, C. chacoense, C. chinense, C. baccatum and C. pubescens can show dormancy (12,16). An after-ripening period of about 6 weeks is required at room temperature to remove dormancy (12).
II. Germination regimes for non-dormant seeds
Capsicum spp.
BP; TP: 20°/30°C (16h/8h): 14d (ISTA,AOSA)
C. annuum
Constant temperatures: 15.5°-37.5°C (1); 21°-26.5°C (2); 15°-25°C (3); 14°-34°C (4); 20°C, light, 5x10-5 mol m-2 s-1, 12h (5); 18°-30°C (7); 25°C, dark (10,14,15,17)
III. Unsuccessful dormancy-breaking treatments
C. annuum
Pre-soak: 5h, 21°C (1); 2-8d (19)
Pre-dry: 22°C, 32°C, 37°C, 1-7d (2)
Light: incandescent (9); infra red (10)
Potassium nitrate: co-applied, 0.2% (8)
Indoleacetic acid: co-applied, 1000 ppm (19)
GA4/7: co-applied, 10-100 ppm (19,20,21)
Kinetin: co-applied, 10-100 ppm (19)
Oxygen: 10, 100%, at 25°C, 15°C (21)
Acetone: pre-applied, 8h, germinate at 15°C, dark (15)
Chloroform: pre-applied, 8h, germinate at 15°C, dark (15)
Dichloromethane: pre-applied, 8h, germinate at 15°C, dark (15)
Dimethylsulphoxide: pre-applied, 8h, germinate at 15°C, dark (15)
Sodium hypochlorite: pre-applied, 5 min, 1%, rinse, then hydrochloric acid, pre-applied, 10 min, 10-2 N (5)
Removal of seed covering structures: germinate at 25°C (20)
C. annuum var minimum
Constant temperatures: 15°-35°C (16)
C. baccatum
Constant temperatures: 15°C, 20°C, 25°C, 35°C (16)
C. chinense
Constant temperatures: 15°-35°C (16)
C. pubescens
Constant temperatures: 15°C (16)
IV. Partly-successful dormancy-breaking treatments
C. annuum
Constant temperatures: 15°C, 35°C (16); 22.5°C, light (12)
Warm stratification: 30°C, 12,24,48h, germinate at 15°C, dark (15)
Pre-soak: 24h (13)
Potassium cyanide: pre-applied, 24h, 10-3 M (13)
Potassium nitrate: pre-applied, 3,6,9d, 3%, at 20°C, germinate at 15°C, dark (15)
Sodium azide: pre-applied, 24h, 10-3 M (13)
Sodium hypochlorite: pre-applied, 5 min, 1% (5)
Acetone: pre-applied, 8h, vacuum dry, 1h, imbibe, 30°C, 48h, germinate at 15°C, dark (15)
Palmitic acid: pre-applied, 8h, 10-4 M, dissolved in acetone, vacuum dry, 1h, imbibe, 30°C, 48h, germinate at 15°C, dark (15)
Stearic acid: pre-applied, 8h, 10-4 M dissolved in acetone, vacuum dry, 1h, imbibe, 30°C, 48h, germinate at 15°C, dark (15)
Oleic acid: pre-applied, 8h, 10-4 M dissolved in acetone, vacuum dry, 1h, imbibe, 30°C, 48h, germinate at 15°C, dark (15)
Linoleic acid: pre-applied, 8h, 10-4 M dissolved in acetone, vacuum dry, 1h, imbibe, 30°C, 48h, germinate at 15°C, dark (15)
Linolenic acid: pre-applied, 8h, 10-4 M dissolved in acetone, vacuum dry, 1h, imbibe, 30°C, 48h, germinate at 15°C, dark (15)
Polyethylene glycol 6000: pre-applied, 5d, -8 bar at 15°C, germinate at 25°C (22); pre-applied, 5d, -8 bar, plus potassium chloride, 10-1, 10-2 M, 15°C, germinate at 25°C (22); pre-applied, 5d, -8 bar, plus potassium nitrate, 10-1, 10-2 M, 15°C, germinate at 25°C (22); pre-applied, 5d, -8 bar, plus GA3, 2.5, 25, 100 ppm, 15°C, germinate at 25°C (22)
Hydroxylamine hydrochloride: pre-applied, 24h, 10-3 M (13)
Oxygen: (14, 18)
GA3: co-applied, 200-800 ppm (18)
C. baccatum
Constant temperatures: 30°C (16)
Warm stratification: 30°C, 35°C, 45d, germinate at 30°/15°C (16h/8h) (16)
C. chacoense
Constant temperatures: 22.5°C, light (12)
C. pubescens
Constant temperatures: 20°C, 30°C, 35°C (16)
Warm stratification: 30°C, 35°C, 45d, germinate at 30°/15°C (16h/8h) (16)
C. frutescens
Constant temperatures: 15°C, 20°C, 25°C, 35°C (16); 22.5°C, light (12)
V. Successful dormancy-breaking treatments
Capsicum spp.
Potassium nitrate (ISTA)
Light, Potassium nitrate (AOSA)
C. annuum
Warm stratification: 20°C, 25°C, 30°C, 35°C, 45d, then 30°/15°C (16h/8h) (16); 15°C, 65d, then 30°/15°C (16h/8h) (16)
GA3: co-applied, 100 ppm, 25°C, any light regime (10); co-applied, 1000 ppm (18)
Removal of seed covering structures: germinate at 15°C (20)
Oxygen: 40, 60%, at 15°C, 25°C (21)
GA4/7: co-applied, 500, 1000 ppm (19)
C. baccatum
Warm stratification: 20°C, 25°C, 45d, then 30°/15°C (16h/8h) (16)
C. chinense
Warm stratification: 20°C, 25°C, 30°C, 35°C, 45d, then 30°/15°C (16h/8h) (16); 15°C, 54d, then 30°/15°C (16h/8h) (16)
C. frutescens
Constant temperatures: 30°C (16)
Warm stratification: 15°C, 65d, then 30°/15°C (16h/8h) (16)
C. pubescens
Constant temperatures: 25°C (16)
Warm stratification: 20°C, 45d, then 30°/15°C (16h/8h) (16); 15°C, 65d, then 30°/15°C (16h/8h) (16)
VI. Comment
It would appear that no special precautions are necessary for the light environment because although incandescent light is inhibitory the fluorescent light sources likely to be used in germination cabinets do not inhibit Capsicum seed germination - but neither are they reported to promote germination (9). Nevertheless if at all possible the light regime given in Chapter 6 should be provided.
Non-dormant seeds of all Capsicum spp. germinate well when tested over the constant temperature range 15°-30°C (1,3,4,6,7,15,16) and non-dormant seeds of C. baccatum also germinate fully at 10°C and 13°C (6,11). The alternating temperature regimes 15°/30°C, 15°/27°C or 20°/30°C promote the germination of dormant seeds of C. annuum, C. baccatum, C. chinense, C. frutescens and C. pubescens quite substantially (6,16). Dormant seeds of C. annuum var minimum, C. baccatum and C. chinense fail to germinate when tested at constant temperatures of 15° to 30°C for up to 60 days, but germinate promptly when transferred to the alternating temperature regime 30°/15°C (16h/8h) (16). Consequently it is suggested that the AOSA/ISTA prescribed alternating temperature regime of 20°/30°C (16h/8h) is likely to be satisfactory for most gene bank purposes, but that the regime 30°/15°C (16h/8h) provided for more than 14 days may be preferable for the most dormant seeds.
VII. References
1. Cochran, H.L. (1935). Some factors which influence the germination of pepper seeds. Proceedings of the American Society for Horticultural Science, 33, 477-480.
2. Cochran, H.L. (1943). Effect of stage of fruit maturity at time of harvest and method of drying on the germination of pimento seed. Proceedings of the American Society for Horticultural Science, 43, 229-234.
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. Bierhuizen, J.F., Wagenvoort, W.A. and Nilwik, H. (1978). Analysis of the relationship between temperature and germination of sweet pepper. Acta Horticulturae, 83, 195-199.
5. Fieldhouse, D.J. and Sasser, M. (1975). Stimulation of pepper seed germination by sodium hypochlorite treatment. HortScience, 10, 622.
6. Gerson, R. and Honma, S. (1978). Emergence response of the pepper at low soil temperature. Euphytica, 27, 151-156.
7. Kotowski, F. (1926). Temperature relation to germination of vegetable seed. Proceedings of the American Society for Horticultural Science, 24, 176-184.
8. Miguel, M.C. (1975). Report of the working group on the germination of Solanaceae. Seed Science and Technology, 3, 110-115.
9. 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.
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. Randle, W.M. and Honma, S. (1980). Inheritance of low temperature emergence in Capsicum baccatum var. pendulum. Euphytica, 29, 331-335.
12. Randle, W.M. and Honma, S. (1981). Dormancy in peppers. Scientia Horticulturae, 14, 19-25.
13. Roberts, E.H. (1964). The distribution of oxidation-reduction enzymes and the effects of respiratory inhibitors and oxidising agents on dormancy in rice seeds. Physiologia Plantarum, 17, 14-29.
14. Sachs, M., Cantliffe, D.J. and Nell, T.A. (1981). Germination studies of clay-coated sweet pepper seeds. Journal of the American Society for Horticultural Science, 106, 385-389.
15. Sachs, M., Cantliffe, D.J. and Watkins, J.T. (1980). Germination of pepper seed at low temperatures after various pretreatments. Proceedings of the Florida State Horticultural Society, 93, 258-260.
16. Sato, T., Yazawa, S. and Namiki, T. (1982). [Requirement of alternating temperature for germination of pepper seeds.] Scientific Reports of the Kyoto Prefectural University, Agriculture, 34, 21-27.
17. 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 Kahl (Brassica oleracea L. var. caulorapa) and Capsicum (Capsicum annuum L.). Progressive Horticulture, 7, 47-50.
18. Sosa-Coronel, J. and Motes, J.E. (1982). Effect of gibberellic acid and seed rates on pepper seed germination in aerated water columns. Journal of the American Society for Horticultural Science, 107, 290-295.
19. Watkins, J.T. and Cantliffe, D.J. (1983). Hormonal control of pepper seed germination. HortScience, 18, 342-343.
20. Watkins, J.T. and Cantliffe, D.J. (1983). Mechanical resistance of the seed coat and endosperm during germination of Capsicum annuum at low temperature. Plant Physiology, 72, 146-150.
21. Watkins, J.T., Cantliffe, D.J. and Sachs, M. (1983). Temperature and gibberellin-induced respiratory changes in Capsicum annuum during germination at varying oxygen concentrations. Journal of the American Society for Horticultural Science, 108, 356-359.
22. Yaklich, R.W. and Orzolek, M.D. (1977). Effect of polyethylene glycol-6000 on pepper seed. HortScience, 12, 263-264.
DATURA
|
D. ferox L. |
|
|
D. innoxia Mill. |
|
|
D. metel L. [D. fastuosa L.; D.
cornucopia Hort.] |
|
|
D. stramonium L. |
jimson-weed, jametown-weed, thorn-apple |
I. Evidence of dormancy
Freshly harvested seeds of all the above species are likely to be extremely dormant (1-9, 11-14). In seeds of D. ferox after-ripening treatments of 3 years at room temperature have not been sufficient to remove dormancy (11).
II. Germination regimes for non dormant seeds
D. ferox
Alternating temperatures: 20°/30°C (15h/9h) (1-4,6,7,11)
D. innoxia
Constant temperatures: 20°C (10)
D. metel
TP; BP; S: 20°/30°C (16h/8h); 20°C: 21d (ISTA)
Constant temperatures: 30°C (10)
D. stramonium
TP; BP; S: 20°/30°C (16h/8h); 20°C: 21d (ISTA)
Constant temperatures: 25°C (10)
Alternating temperatures: 20°/30°C (16h/8h) (12)
III. Unsuccessful dormancy-breaking treatments
D. ferox
Constant temperatures: 10°C, 20°C, 30°C (11)
Alternating temperatures: 10°/20°C, 20°/10°C, 10°/30°C, 30°/10°C, 20°/30°C, 30°/20°C (9h/15h) (11)
Warm stratification: 20°C, 3-4w, germinate at 20°/30°C (15h/9h), dark (3)
Pre-soak: 3d (11)
Thiourea: co-applied, 0.1, 0.25, 0.5, 1%, decoated seeds (11)
Light: continuous dark (2,6); far red, 9500 erg cm-2 sec-1, 3 min (11)
Abscisic acid: co-applied, 10-4 M (2)
GA3: co-applied, 50-200 ppm (7)
D. innoxia
Thiourea: pre-applied, 16h, 1% (9)
Ascorbic acid: pre-applied, 18h, 2% (8)
X-rays: 2000-8000 R, 770 R/min (9)
Pre-dry: 40°C, 48,96h (9); 60°C, 96h (9)
Scarification: hand (8); sulphuric acid (8)
D. metel
Removal of seed covering structures: testa (14)
Scarification: concentrated sulphuric acid (14)
D. stramonium
Ethylene: co-applied, 1-100 ppm (13)
Light: red, 1.9x10-4 W cm-2, 5 min, after 24h (13)
IV. Partly-successful dormancy-breaking treatments
D. ferox
Alternating temperatures: 20°/30°C (15h/9h) (2,3,4); 20°/30°C (15h/9h) in light (1)
Humidification: 25°C, 100% rh, 7d, germinate at 20°/30°C (15h/9h), dark, 2d, then red light, 9x10-4 W cm-2, 0.5-10 min (6)
Removal of seed covering structures: decoated (4,7,11); decoated, germinate at 20°/30°C (15h/9h), dark, 1-3d, then red light, 20 min (4)
Light: 400 lux, 9h/d (11); red, 900 erg cm-2 s-1, 20 min, after 48h imbibition (1); red, 1-100 min (2,4); red, 0.5-10 min (6); red, 10 min, after 16h imbibition (11); blue, 320-480nm, 1500 erg cm-2 s-1 (11)
GA3: co-applied, 500 ppm, intact seeds (7); co-applied, 50 ppm, decoated seeds (7); co-applied, 100, 200 ppm, in dark, decoated seeds (11); pre-applied, 200 ppm, 2,3d, then decoated (7)
D. innoxia
Thiourea: pre-applied, 18h, 0.2-4% (8); pre-applied, 16h, 0.25-0.75% (9); pre-applied, 18h, 0.02%, plus ascorbic acid, 0.02% (8); pre-applied, 18h, 0.2%, plus ascorbic acid, 0.3%, 0.4% (8); pre-applied, 18h, 0.3%, plus ascorbic acid, 0.2, 0.3% (8)
Ascorbic acid: pre-applied, 18h, 0.2-1% (8); pre-applied, 16h, 0.25-1% (9)
Electric shock: in acidified water, 220V, 15-60s (9)
X-rays: 500-1000 R, 770 R/min (9)
Pre-dry: 60°C, 48h (9)
Storage: 4°C, -6°C, 48,96h (9); 20°C, 100% rh, 3-4w (3)
D. metel
Pre-soak: 10-12h (14)
Ethanol: pre-applied, 3-4h, 90% (14)
V. Successful dormancy-breaking treatments
D. ferox
Alternating temperatures: 20°/30°C (15h/9h), 1-3d, then seeds decoated, plus GA3, co-applied, 200 ppm (7)
Warm stratification: 35°C, 2d, decoated seeds, germinate at 20°/30°C (15h/9h) in light, 400 lux, 9h/d (11)
Sodium azide: co-applied, 5x10-3 M, isolated embryos (5)
Removal of seed covering structures: plus GA3, co-applied, 100-500 ppm, at 20°/30°C (15h/9h) in light, white or red, 900 erg cm-2 s-1, 20 min, after 2d imbibition (7); decoated, germinate at 20°/30°C (15h/9h), 1-3d, then plus GA3, co-applied, 200 ppm (7); decoated, then GA3, pre-applied, 24h, 200 ppm, germinate at 20°/30°C (15h/9h) (7)
D. metel, D. stramonium
Pre-chill, Scratch hard seeds (ISTA)
VI. Comment
To germinate seeds of Datura spp. it is necessary to provide both alternating temperatures and light. In addition gibberellic acid is very effective in promoting germination and may also be required. It is suggested that successful germination test regimes for seeds of Datura spp. are likely to include more than one of the following; an alternating temperature regime of 20°/30°C (15-16h/8-9h); a short duration light treatment similar to those given in Chapter 6 or those provided for D. ferox above; seed coat removal; GA3, either co-applied at about 50-300 ppm, or pre-applied for 24 hours at about 2000 ppm.
VII. References
1. Burkart, S. and Sánchez, R.A. (1969). Interaction between an inhibitor present in the seeds of Datura ferox and light in the control of germination. Botanical Gazette, 130, 42-47.
2. De Miguel, L.C. (1980). Changes in levels of endogenous inhibitors during dormancy breakage in Datura ferox L. seeds. Zeitschrift für Pflanzenphysiologie, 96, 415-421.
3. De Miguel, L.C. and Soriano, A. (1974). The breakage of dormancy in Datura ferox seeds as an effect of water absorption. Weed Research, 14, 265-270.
4. Gugliada, M.L., Soriano, A. and Burkart, S. (1967). The seed coat effect in relation to the photoinduction of germination of Datura ferox L. Canadian Journal of Botany, 45, 377-381.
5. Sánchez, R.A. and De Miguel, L.C. (1983). Ageing of Datura ferox seed embryos during dry storage and its reversal during imbibition. Zeitschrift für Pflanzenphysiologie, 110, 319-329.
6. Sánchez, R.A., Eyherabide, G. and De Miguel, L.C. (1981). The influence of irradiance and water deficit during fruit development on seed dormancy in Datura ferox L. Weed Research, 21, 127-132.
7. Sánchez, R.A., Soriano, A. and Slabnik, E. (1967). The interaction of the seed coat and gibberellic acid in the germination of Datura ferox L. Canadian Journal of Botany, 45, 371-376.
8. Singh, C. (1974). Seed germination in Datura innoxia Mill. Indian Journal of Experimental Biology, 12, 291.
9. Singh, C., Bhan, A.K. and Kaul, B.L. (1974). The role of some physical and chemical agents in the improvement of seed germination in Datura innoxia. Seed Science and Technology, 2, 421-425.
10. Singh, C. and Kaul, B.L. (1976). Note on the effect of temperature on seed germination in Datura species. Seed Research, 4, 134-135.
11. Soriano, A., Sánchez, R.A. and De Eilberg, B.A. (1964). Factors and processes in the germination of Datura ferox L. Canadian Journal of Botany, 42, 1189-1203.
12. 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.
13. Taylorson, R.B. (1979). Response of weed seeds to ethylene and related hydrocarbons. Weed Science, 27, 7-10.
14. Zutsi, U. and Atal, C.K. (1970). Scopoletin induced inhibition of germination in Datura species. Herba Hungarica, 9, 51-54.
LYCOPERSICON
|
L. esculentum Mill. [L. lycopersicon Karst.;
L. lycopersicum (L.) Farwell; Solanum lycopersicum] |
tomato |
I. Evidence of dormancy
Seeds of L. esculentum can show considerable dormancy (28). In addition secondary dormancy can be induced by chilling (28,32), warm stratification (19) or from prolonged exposure to far red light (15,24). Finally it should be noted that the pattern of germination of non-dormant seeds can be erratic (33).
II. Germination regimes for non-dormant seeds
BP; TP: 20°/30°C (16h/8h): 14d (ISTA, AOSA)
III. Unsuccessful dormancy-breaking treatments
Constant temperatures: 25°C, 30°C, dark (28)
Alternating temperatures: 5°/15°C (12h/12h) (25)
Pre-chill: 0°-14°C, 3d (32); 6°C, 20d (28); 8°C, 8-24h (5)
Warm stratification: 35°C, 1-5w, germinate at 25°C (19)
Light: incandescent (6,20,28,36); far red (24,35); far red, 0.132x10-6 mol cm-2 s-1 (6); far red, continuous, 5 W m-2 (9); far red, intermittent, 2 min/h (9); far red, 30 min (9); far red, 14x10-6 W cm-2, 1,16 min, prolonged irradiation (15); far red, 185x10-6 W cm-2, 15s-10 min (16, 36); far red, intermittent, 1-4 min/30-120 min (light/dark) (37); far red, 500 ergs cm-2 s-1 (20); infra red, at 25°C (22); diffuse daylight, 12-24h/d, at 20°/30°C (16h/8h) (18); white, continuous, at 15°C (28); white, continuous, at 17.5°C (35)
Kinetin: co-applied, 10, 20 ppm (4)
GA3: co-applied, 10-500 ppm (18); co-applied, 100, 200 ppm (26)
Potassium nitrate: co-applied, 10-2 M (26); co-applied, 0.2% (17); pre-applied, 2%, dark imbibition, 6d, 20°C, then pre-dry, 2d, 20°C (hardening) (34)
Wetting/Drying: 3 cycles (24h/48h), 20°C (hardening) (34); 1 cycle (1d, 2d/1d), 20°C (hardening) (5)
IV. Partly-successful dormancy-breaking treatments
Constant temperatures: above 35°C (2,19)
Alternating temperatures: 20°/30°C (16h/8h), dark or light (13,18,28)
Light: continuous, 50-1000 ergs cm-2 s-1, at 27°C (20); white, 4-12h/d, at 20°/30°C (16h/8h) (18); white, 8h/d, at 20°/30°C (16h/8h) (13); red, 295x10-6 W cm-2, 15s-1 min, at 20°C, alone or after far red (16,35,37)
Potassium nitrate: co-applied, 0.2%, at 20°/30°C (16h/8h) in light or dark (7); co-applied, 10-1 M (26); co-applied, 10-2 M, plus kinetin, co-applied, 1-50 ppm (26); co-applied, 10-2 M, plus kinetin, co-applied, 10 ppm, plus GA3, co-applied, 10 ppm (26); plus tripotassium phosphate, pre-applied, 5,10,20d, 10°C, 24°C, 1-2%, germinate at 15°C (hardening) (5,10); plus tripotassium phosphate, pre-applied, 1-8d, 0.2-1.8% (hardening) (14)
Polyethylene glycol: pre-applied, 5-20d, 10°C, 15°C, -5 to -15 bars, germinate at 15°C (hardening) (5,10)
Mannitol: pre-applied, 4h-2d, 0.6M (hardening) (9)
GA3: pre-applied, 12h, 10-500 ppm, germinate at 20°/30°C (16h/8h), continuous dark (18); pre-applied, 1-48h, 200 ppm, germinate at 20°/30°C (16h/8h), continuous light or dark, or 6 cycles light/dark (12h/12h), or 1 cycle 3d/3d dark/light or light/dark (18); co-applied, 100 ppm, infra red (22); co-applied, 10, 50, 500 ppm (26)
V. Successful dormancy-breaking treatments
Potassium nitrate (ISTA)
Light, Potassium nitrate (AOSA)
Constant temperatures: 10°C, dark (23); 16°-22°C, dark (1); 20°C, dark (15,16,35,36); 25°C, dark (4,5,9,22,37); 27°C, dark (20); 10°-30°C (12); 15°-30°C (19); 14°-24°C (27); 15°C, 20°C (29); 20°-26°C (30,32); 20°-26°C, light, 12h/d (31); 25°-30°C under many different light regimes (15); 13°-25°C, fluorescent light, 8h/d (3); 15°-29°C, white light, 8h/d (11); 26°-32°C, low light intensity, 12h/d (30); 20°C, red light, 1 min, 0.3x10-6 W cm-2 (15,16); 27°C, white light or 40 min or continuous red light, 60 ergs cm-2 s-1 (20); 20°C, first 24h in dark (35); 20°C, light, Pfr/P=0.4 (6,16)
Alternating temperatures: 17°/27°C (16h/8h), light, 4000 fc, 8h/d (8); 20°/30°C (16h/8h), dark (24); 20°/30°C (16h/8h), fluorescent light, 175-200 fc, 8h/d (24)
Pre-chill: 10°C, 4m, germinate at 27°C (8)
Potassium nitrate: co-applied, 0.2%, at 20°/30°C (16h/8h), light (13); co-applied, 10-2 M, at 30°C or 20°/30°C (16h/8h), daylight (28)
Mannitol: pre-applied, 3-7d, 0.6M, in dark, germinate at 25°C in any light condition (9)
Scarification: cut endosperm over radicle region, germinate at 22°C, light, 16h/d (33)
VI. Comment
The germination of tomato seeds is reported to be dependent on the phytochrome ratio resulting from the light regime in which they are tested (6,9,15,16,18,20-22,24,28,35,36,37). Several authors have reported apparently contradictory effects of light on tomato seed dormancy and germination (7,28). The reader is referred to Chapter 6 for clarification of the effect of phytochrome on germination and the high irradiance reaction - which explain the apparently contradictory results. In particular the light treatment given in Chapter 6 is recommended for this genus. The first 8 to 16 hours after the onset of imbibition are the most critical with regard to the light environment (9,16). After 24 hours of imbibition the effect of light is minimal (35). In passing it should be noted that coloured filter papers - particularly if seeds are germinated between papers - such as blue grey, brown or dark green can inhibit the germination of tomato seeds (24).
Optimum temperatures for germination appear to be constant temperatures between 25° and 30°C (15) or an alternating temperature of 20°/30°C (16h/8h) (24). The range 25° to 30°C appears to be an optimum temperature range for germination since seeds within this range are less dependent upon the light regime for germination, but the germination of the most dormant seeds is not promoted at either these constant temperatures or the alternating temperature regime 20°/30°C (28), but co-applied potassium nitrate may further promote germination in these regimes (13,28).
As a practical regime for seed banks it is suggested that seeds be tested for germination at an alternating temperature of 20°/30°C (16h/8h) with potassium nitrate, co-applied, 0.2% with the light regime given in Chapter 6. Incidentally co-applied potassium nitrate at low concentrations (10-1 M) is not deleterious to aged seeds and may enhance the rate of germination (26). (In commerce imbibition in potassium nitrate or water followed by drying back is known as hardening and is often used with tomato seeds.)
VII. References
1. Abdul-Baki, A.A. and Stoner, A. (1978). Germination promoter and inhibitor in leachates from tomato seeds. Journal of the American Society for Horticultural Science, 103, 684-686.
2. Berry, S.Z. (1969). Germinating response of the tomato at high temperature. HortScience, 4, 218-219.
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. Boscut, S. (1981). Effects of kinetin and salinity on germination of tomato, barley and cotton seeds. Annals of Botany, 48, 81-84.
5. Bussell, W.T. and Gray, D. (1976). Effects of pre-sowing seed treatments and temperatures on tomato seed germination and seedling emergence. Scientia Horticulturae, 5, 101-109.
6. Egles, D. and Rollin, P. (1968). La photosensibilité des graines de tomate var. St. Pierre. Comptes Rendus de l'Académie de Science, Paris, 266D, 1017-1020.
7. Eifrig, H. (1962). Zur Methodik der Keimprüfung einiger Germiisesämereien. Proceedings of the International Seed Testing Association, 27, 649-656.
8. El-Sayed, M.N. and John, C.A. (1973). Heritability studies of tomato emergence at different temperatures. Journal of the American Society for Horticultural Science, 98, 440-443.
9. Georghiou, K., Thanos, C.A., Tafax, T.P. and Mitrakos, K. (1982). Tomato seed germination, osmotic pretreatment and far red inhibition. Journal of Experimental Botany, 33, 1068-1075.
10. Gray, D. and Bussell, W.T. (1974). Effects of temperature on tomato seed germination. National Vegetable Research Station, Annual Report 1974, 79-80.
11. Guy, R. (1981). Influence de la temperature sur la dureé de germination des semences de dix espéces potagères. Revue Suisse de Viticulture, d'Arboriculture et d'Horticulture, 13, 219-225.
12. Harrington, J.F. (1963). The effect of temperature on the germination of several kinds of vegetable seeds. 16th International Horticultural Congress, 2, 435-441.
13. Kelk, O.M. (1953). Some studies on the germination of tomato seed. Proceedings of the Association of Official Seed Analysts, 43, 89.
14. Maluf, W.R. and Tigchelaar, E.C. (1980). Responses associated with low temperature seed germinating ability in tomato. Journal of the American Society for Horticultural Science, 105, 280-283.
15. Mancinelli, A.L., Borthwick, H.A. and Hendricks, S.B. (1966). Phytochrome action in tomato seed germination. Botanical Gázette, 127, 1-5.
16. Mancinelli, A.L., Yaniv, Z. and Smith, P. (1967). Phytochrome and seed germination. I. Temperature dependence and relative Pfr levels in the germination of dark-germinating tomato seeds. Plant Physiology, 42, 333-337.
17. Miguel, M.C. (1975). Report of the working group on the germination of Solanaceae. Seed Science and Technology, 3, 110-115.
18. Mittal, S.P. and Mathur, S.N. (1965). Effect of white light and gibberellin on tomato seed germination. Physiologia Plantarum, 18, 798-804.
19. Mobayen, R.G. (1980). Germination and emergence of citrus and tomato seeds in relation to temperature. Journal of Horticultural Science, 55, 291-297.
20. Mondain-Monval, O.D. (1963). Etude de l'action de la lumière sur la germination des graines de tomate (Lycopersicum esculentum Miller) variété Marmande. Comptes Rendus des Séances de l'Académie de Science, 257, 3646-3648.
21. 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.
22. 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.
23. Ng, T.J. and Tigchelaar, E.C. (1973). Inheritance of low temperature seed sprouting in tomato. Journal of the American Society for Horticultural Science, 98, 314-316.
24. Nutile, G.E. and Hackett, T.E. (1959). Light filtering effect of blotters on the germination of seed of tomato (Lycopersicon esculentum). Proceedings of the Association of Official Seed Analysts, 49, 93-97.
25. Patterson, B.D., Paull, R. and Smillie, R.M. (1978). Chilling resistance in Lycopersicon hirsutum Humb. & Bonpl., a wild tomato with a wide altitudinal distribution. Australian Journal of Plant Physiology, 5, 609-617.
26. Puls, E.E. Jr. and Lambeth, V.N. (1974). Chemical stimulation of germination rate in aged tomato seeds. Journal of the American Society for Horticultural Science, 99, 9-12.
27. Scott, S.J. and Jones, R.A. (1982). Characterization of seed germination responses of Lycopersicon species over a wide temperature range. HortScience, 17, 512.
28. Shuck, A.L. (1936). The germination of secondary dormant tomato seeds and their formation. Proceedings of the International Seed Testing Association, 8, 136-158.
29. Smith, P.G. and Millett, A.E. (1964). Germination and sprouting responses of the tomato at low temperatures. Proceedings of the American Society for Horticultural Science, 84, 480-484.
30. Thompson, P.A. (1974). Characterisation of the germination responses to temperature of vegetable seeds. I. Tomatoes. Scientia Horticulturae, 2, 35-54.
31. Thompson, P.A. and Fox, D.J.C. (1976). The germination responses of vegetable seed in relation to their history of cultivation by man. Scientia Horticulturae, 4, 1-14.
32. Went, F.W. (1961). Problems in seed viability and germination. Proceedings of the International Seed Testing Association, 26, 674-685.
33. Whittington, W.J. and Fierlinger, P. (1972). The genetic control of time to germination in tomato. Annals of Botany, 36, 873-880.
34. Wickham, B.D. and Nichols, M.A. (1976). Germination studies with "hardened" vegetable seed. New Zealand Journal of Experimental Agriculture, 4, 457-461.
35. Yaniv, Z. and Mancinelli, A.L. (1967). Phytochrome and seed germination. II. Changes of Pfr requirement for germination in tomato seed. Plant Physiology, 42, 1147-1148.
36. Yaniv, Z. and Mancinelli, A.L. (1968). Phytochrome and seed germination. IV. Action of light sources with different spectral energy distribution on the germination of tomato seeds. Plant Physiology, 43, 117-120.
37. Yaniv, Z., Mancinelli, A.L. and Smith, P. (1967). Phytochrome and seed germination. III. Action of prolonged far red irradiation on the germination of tomato and cucumber seeds. Plant Physiology, 42, 1479-1482.
NICOTIANA
|
N. alata Link & Otto |
|
|
N. acuminata |
|
|
N. benthamiana |
|
|
N. bigelovii (Torr.) Wats. |
|
|
N. corymbosa |
|
|
N. eastii |
|
|
N. glutinosa L. x N. tabacum L. |
|
|
N. goodspeedii |
|
|
N. gossei Domin |
|
|
N. maritima |
|
|
N. megalosiphon |
|
|
N. miersii |
|
|
N. nudicaulis |
|
|
N. rustica L. |
nicotine tobacco |
|
N. x sanderae Wats. |
|
|
N. suaveolens Lehm. |
|
|
N. suaveolens Lehm. x N. langsdorffii
Weinmann |
|
|
N. tabacum L. |
tobacco |
|
N. trigonophylla |
|
I. Evidence of dormancy
Seeds of the cultivated and wild tobacco species and the hybrids cited above can show considerable dormancy (1-4,9,12,13,17,20,27,29). Seed dormancy is said to persist for 1-3 weeks after harvesting (2). However, if light is not applied to promote germination in the test procedure, tobacco seeds may not germinate at all after 6 months or even many years dry storage at room temperature (10,23).
II. Germination regimes for non-dormant seeds
N. alata, N. x sanderae
TP: 20°/30°C (16h/8h); 20°C: 14d (ISTA)
TP: 20°/30°C (16h/8h): 12d (AOSA)
N. suaveolens
TP: 20°/30°C (16h/8h); 20°C: 14d (ISTA)
N. tabacum
TP: 20°/30°C (16h/8h): 16d (ISTA)
TP: 20°/30°C (16h/8h): 14d (AOSA)
III. Unsuccessful dormancy-breaking treatments
N. tabacum
Constant temperatures: 20°C, 25°C, dark, continuous (3,4,8,9,16,23,27)
Pre-chill: 10°C, dark, 8d, germinate at 25°C, dark or light (3); 5°-17°C, dark, 2w, germinate in dark (9)
Pre-soak: 60°C, 75°C, 90°C, 0.25,0.5 min (3); 60h (12)
Oxygen: 40-80%, germinate in dark (3)
Acetic acid: pre-applied, 24h, 10-1, 1 M, germinate in dark (3)
Butyric acid: pre-applied, 24h, 10-2, 10-1 M, germinate in dark (3)
Hydrogen peroxide: pre-applied, 24h, 5-50%, germinate in light (3)
Ether: pre-applied, 15,30,60 min, germinate in dark (3)
Potassium phosphate: co-applied, 10-3 M, plus ammonium citrate, 5x10-3, 10-2 M, co-applied, dark (7)
Glucose: co-applied, 5x10-3 M, at 25°C, light, 50 lux, 10 min (15)
Kinetin: co-applied, 0.01-50 ppm, dark (16)
Ammonium nitrate: co-applied, 5x10-3 -10-1 M, dark (25)
Ammonium sulphate: co-applied, 5x10-3 -10-1 M, dark (5,25)
Ammonium chloride: co-applied, 5x10-3 -10-1 M, dark (5,25)
Potassium sulphate: co-applied, 5x10-3 -10-1 M, dark (5,25)
Potassium chloride: co-applied, 5x10-3 -10-1 M, dark (5,25)
Potassium phosphate: co-applied, 5x10-3 -10-1 M, dark (5,25)
Ammonium phosphate: co-applied, 0.6x10-3 -0.2x10-1 M, dark (25)
Glycine: co-applied, 10-2 M, dark (30)
A-Alanine: co-applied, 10-2 M, dark (30)
L-Aspartic acid: co-applied, 10-2 M, dark (30)
Glutamic acid: co-applied, 10-2 M, dark (30)
A-Ketoglutaric acid: co-applied, 10-2 M, dark (30)
Scarification: concentrated sulphuric acid, 0.5,1 min (3)
IV. Partly-successful dormancy-breaking treatments
N. corymbosa, N. maritima, N. megalosiphon, N. miersii, N. nudicaulis
Sodium hypochlorite: pre-applied, 15-30 min, 2%, rinse in acetone (2)
N. tabacum
Pre-chill: 10°C, 8d, in light, germinate at 25°C, dark (3); 10°C, 2d, germinate at 25°C, dark (9)
Pre-soak: 60h, in non-dormant tobacco seed filtrate (1g ground seed/10ml water), germinate at 25°C, dark (12,13)
Pre-dry: 85°-90°C, 1h, germinate at 25°C, dark (18)
Potassium nitrate: co-applied, 10-2 M, at 25°C, dark (16); co-applied, 2x10-2 M, at 25°C, dark (4,15); co-applied, 2x10-2-8x10-2 M, at 25°C, dark (5); co-applied, 10-3-10-2 M, at 25°C, dark (15); pre-applied, 8h, 100-1000 ppm, germinate at 25°C, dark (20); pre-applied, 10-4-10-2 M, germinate at 25°C, dark (3)
Potassium nitrite: co-applied, 10-3-10-2 M, at 25°C, dark (15)
Ammonium nitrate: co-applied, 10-2 M, at 25°C, dark (15); co-applied, 2x10-2 M, at 25°C, dark (4); co-applied, 2x10-2-8x10-2 M, at 25°C, dark (5); pre-applied, 24h, 10-1-10-4 M, germinate at 25°C, dark (3)
Ammonium sulphate: pre-applied, 24h, 10-1-10-4 M, germinate at 25°C, dark (3)
Ammonium hydroxide: pre-applied, 24h, 10-2-10-4 M, germinate at 25°C, dark (3)
Potassium sulphocyanate: pre-applied, 24h, 10-2-10-4 M, germinate at 25°C, dark (3)
Potassium sulphate: pre-applied, 24h, 10-2-10-4 M, germinate at 25°C, dark (3)
Potassium hydroxide: pre-applied, 24h, 10-2-10-4 M, germinate at 25°C, dark (3)
Sodium sulphocyanate: pre-applied, 24h, 10-2-10-4 M, germinate at 25°C, dark (3)
Sodium iodide: pre-applied, 24h, 10-2-10-4 M, germinate at 25°C, dark (3)
Sodium sulphate: pre-applied, 24h, 10-2-10-4 M, germinate at 25°C, dark (3)
Sodium nitrate: pre-applied, 24h, 10-1-10-4 M, germinate at 25°C, dark (3); co-applied, 10-2 M, at 25°C, dark (15)
Sodium hydroxide: pre-applied, 24h, 10-2-10-4 M, germinate at 25°C, dark (3)
Lithium sulphate: pre-applied, 24h, 10-2-10-4 M, germinate at 25°C, dark (3)
Lithium nitrate: co-applied, 10-2 M, at 25°C, dark (15)
Nickel sulphate: pre-applied, 24h, 10-2-10-4 M, germinate at 25°C, dark (3)
Zinc sulphate: pre-applied, 24h, 10-2-10-4 M, germinate at 25°C, dark (3)
Aluminium nitrate: pre-applied, 24h, 10-3, 10-4 M, germinate at 25°C, dark (3)
Cobalt nitrate: pre-applied, 24h, 10-2-10-4 M, germinate at 25°C, dark (3)
Hydrogen peroxide: 0.5%, at 25°C, dark (19); pre-applied, 27h, 5-50%, germinate at 25°C, dark (3)
Ether: pre-applied, 15,30,60 min, germinate at 25°C, light (3)
Acetic acid: pre-applied, 24h, 10-2-10-4 N, germinate at 25°C, dark (3); co-applied, 10-2 M, plus GA3, co-applied, 10 ppm (24)
Butyric acid: pre-applied, 24h, 10-3, 10-4 N, germinate at 25°C, dark (3)
Citric acid: pre-applied, 24h, 10-1-10-4 N, germinate at 25°C, dark (3); co-applied 5x10-3 M, at 25°C, dark (15); co-applied, 10-2 M, plus GA3, co-applied, 10 ppm (24)
Tartaric acid: pre-applied, 24h, 10-1-10-4 N, germinate at 25°C, dark (3); co-applied, 10-2 M, plus GA3, co-applied, 10 ppm (24)
Malic acid: pre-applied, 24h, 10-1-10-4 N, germinate at 25°C, dark (3); co-applied 5x10-3 M, at 25°C, dark (15); co-applied, 10-2 M, plus GA3, co-applied, 10 ppm (24)
Sulphuric acid: pre-applied, 24h, 10-2-10-5 N, germinate at 25°C, dark (3)
Hydrochloric acid: pre-applied, 24h, 10-3-10-5 N, germinate at 25°C, dark (3)
Phosphoric acid: pre-applied, 12h, 0.5%, germinate at 25°C, dark (13)
Boric acid: pre-applied, 12h, 0.5%, germinate at 25°C, dark (13)
Formalin: pre-applied, 12h, 0.5%, germinate at 25°C, dark (13)
Calcium nitrate: co-applied, 10-2 M, at 25°C, dark (15)
Magnesium nitrate: co-applied, 10-2 M, at 25°C, dark (15)
Barium nitrate: co-applied, 10-2 M, at 25°C, dark (15)
Bismuth nitrate: co-applied, 10-2 M, at 25°C, dark (15)
Hydroxylamine: co-applied, 10-3 M, at 25°C, dark (15)
Glycine: co-applied, 5x10-3, 10-2 M, light, 50 lux, 10 min (15)
Alanine: co-applied, 10-3-10-2 M, light, 50 lux, 10 min (15)
Valine: co-applied, 10-3-10-2 M, light, 50 lux, 10 min (15)
Leucine: co-applied, 5x10-3, 10-2 M, light, 50 lux, 10 min (15)
Arginine: co-applied, 10-3-10-2 M, light, 50 lux, 10 min (15)
Aspartic acid: co-applied, 10-3-10-2 M, light, 50 lux, 10 min (15)
Glutamic acid: co-applied, 10-3-10-2 M, light, 50 lux, 10 min (15)
Tryptophane: co-applied, 10-3-10-2 M, light, 50 lux, 10 min (15)
Asparagine: co-applied, 10-3-10-2 M, light, 50 lux, 10 min (15)
Glycerine: co-applied, 5x10-3 M, light, 50 lux, 10 min (15)
Pyruvic acid: co-applied, 5x10-3 M, light, 50 lux, 10 min (15); co-applied, 10-2 M, plus GA3, co-applied, 10 ppm (24)
A-Ketoglutaric acid: co-applied, 5x10-3 M, light, 50 lux, 10 min (15); co-applied, 10-2 M, plus GA3, co-applied, 10 ppm (24)
Succinic acid: co-applied, 5x10-3 M, light, 50 lux, 10 min (15); co-applied, 10-2 M, plus GA3, co-applied, 10 ppm (24)
Fumaric acid: co-applied, 5x10-3 M, light, 50 lux, 10 min (15); co-applied, 10-2 M, plus GA3, co-applied, 10 ppm (24)
Indoleacetic acid: co-applied, 10-7 M, at 25°C, dark (23)
Kinetin: co-applied, 10 ppm, at 25°C, dark (5); co-applied, 10, 20 ppm, plus potassium nitrate, or ammonium chloride, or potassium chloride, co-applied, 2x10-2, 5x10-2 M (5)
Benzyladenine: co-applied, 10-7 M, at 25°C, dark (23)
GA1: co-applied, 5x10-6-5x10-4 M, plus potassium nitrate, co-applied, 10-2 M, at 25°C, dark (6)
GA2: co-applied, 5x10-6-5x10-4 M, plus potassium nitrate, co-applied, 10-2 M, at 25°C, dark (6)
GA3: pre-applied, 24h, 100, 500 ppm, germinate at 25°C, dark (17); pre-applied, 8h, 1-100 ppm, plus potassium nitrate, pre-applied, 8h, 100 ppm (20); co-applied, 30 ppm, at 25°C, dark (4); co-applied, 0.3-30 ppm, at 25°C, dark (5); co-applied, 1-100 ppm, at 25°C, dark (16,20); co-applied, 10-4 M, at 25°C, dark (23); co-applied, 5-20 ppm, at 25°C, dark (26); co-applied, 100 ppm at
25°C, dark (19); co-applied, 0.3-30 ppm, plus potassium nitrate or ammonium nitrate, co-applied, 4x10-2, 8x10-2 M, at 25°C, dark (4,5); co-applied, 10 ppm, plus ammonium chloride or ammonium sulphate or potassium chloride or potassium sulphate, co-applied, 5x10-2, 10-1 M, at 25°C, dark (5); co-applied, 10 ppm, plus potassium nitrate, co-applied, 4x10-2 M, plus potassium phosphate, co-applied, 10-2 -4x10-2 M, at 25°C, dark (7); co-applied, 10 ppm, plus ammonium nitrate or ammonium sulphate or ammonium chloride, co-applied, 5x10-3 -10-1 M, at 25°C, dark (25); co-applied, 5x10-6 -5x10-4 M, plus potassium nitrate, co-applied, 10-2 M, at 25°C, dark (6)
GA4: co-applied, 10-7 -5x10-6 M, plus potassium nitrate, co-applied, 10-2 M, at 25°C, dark (6)
V. Successful dormancy-breaking treatments
N. alata
Potassium nitrate (ISTA)
Light (AOSA)
N. acuminata, N. benthamiana, N. bigelovii, N. eastii
Sodium hypochlorite: pre-applied, 15-30 min, 2%, rinse in acetone (2)
N. glutinosa x N. tabacum
Light: 200-400 fc, 8h/d, at 25°C (23)
N. goodspeedii, N. gossei
Sodium hypochlorite: pre-applied, 15-30 min, 2%, rinse in acetone (2)
N. rustica
GA3: pre-applied, 8h, 10-100 ppm, plus potassium nitrate, 250-1000 ppm, germinate at 25°C, diffuse light, 4h/d (20)
N. x sanderae
Potassium nitrate (ISTA)
Light (AOSA)
N. suaveolens
Potassium nitrate (ISTA)
N. tabacum
Potassium nitrate (ISTA)
Light (AOSA)
Alternating temperatures: 20°/30°C (16h/8h), light or dark (14); 20°/30°C (16h/8h), light (21,22,23,27)
Light: diffuse, at 25°C (9); diffuse, at 20°C (10,11); fluorescent, 200-400 fc, 8h/d, at 25°C (23); red, 16-32 min, after 24h dark (8); red, 8-32 min, after 48h dark (8); red, 1-2 min, after 72h dark (8); red, 0.5 min, after 96h dark (8); red, continuous, at 15°-25°C or 20°/30°C (16h/8h) (14,27)
Potassium nitrate: co-applied, 0.2%, at 10°/30°C (16h/8h), diffuse light (22); co-applied, 0.2%, at 20°/30°C (16h/8h), diffuse light (21,22); co-applied, 0.2%, at 20°/30°C (16h/8h), continuous red light, 0.3x10-3 W cm-2 (27); co-applied, 10-2 M, plus kinetin, co-applied, 10 ppm, at 25°C, light, 3h (16)
GA3: (18); pre-applied, 1.5h, 12x10-5 M (1); pre-applied, 24h, 500 ppm (17); co-applied, 10-4 M, with or without indoleacetic acid, 10-7 M, or benzyladenine, 10-7 N, at 20°/30°C (16h/8h), fluorescent light, 200-400 fc, 8h/d (23); co-applied, 50 ppm, plus potassium nitrate, 10-2 M, co-applied, at 25°C, in light, 1h (16,20) Sodium hypochlorite: pre-applied, 15-30 min, 2%, rinse in acetone (2)
N. trigonophylla
Sodium hypochlorite: pre-applied, 15-30 min, 2%, rinse in acetone (2)
VI. Comment
The pre-applied sodium hypochlorite treatment has been used frequently and regularly to remove dormancy in seeds of many species and interspecific hybrids within the genus Nicotiana and is reported to be very useful in breeding programmes and when regenerating collections of diverse germplasm (2).
When germinating seeds of Nicotiana spp. it is essential to provide light (3,8-11,14,20,23,27,28). The light regime provided in Chapter 6 is recommended. Whether the germination test is conducted in the light or dark, the germination of dormant seeds will be promoted more by the use of alternating temperature regimes than it will be at constant temperatures (14,21-23,27): 20°/30°C (16h/8h) appears to be a satisfactory regime (14,21-23,27). Thus the AOSA/ISTA prescriptions are generally satisfactory. If it is not possible to provide an alternating temperature regime and a constant temperature is provided then higher temperatures (30°C) should be avoided because germination may be inhibited: use 20°C (10,14,16).
If further dormancy breaking treatments are required then treatment with gibberellins is likely to be among the more effective (4,5). For successful treatment concentrations see above. Other useful dormancy-breaking agents, in declining order of reported effectiveness are ammonium nitrate, potassium nitrite, potassium nitrate (15). In the case of accessions with considerable dormancy, combinations of gibberellins and potassium nitrate are suggested, co-applied at the concentrations given above, since there can be powerful positive interactions in the effect of these two agents (16,20). Finally if these are insufficient try combining the preceding with the sodium hypochlorite pre-treatment (2).
VII. References
1. Andersen, R.A. (1975). Effects of gibberellic and pretreatments on the germination of hybrid tobacco seeds. Kentucky Agricultural Experiment Station, Lexington, Annual Report, 88, 28.
2. Burk, L. (1957). Overcoming of seed dormancy in Nicotiana. Agronomy Journal, 49, 461.
3. Gardner, W.A. (1921). Effect of light on germination of light sensitive seeds. Botanical Gazette, 71, 249-288.
4. Hashimoto, T. (1958). Increase in percentage of gibberellin-induced dark germination of tobacco seeds by N-compounds. The Botanical Magazine, Tokyo, 71, 845-846.
5. Hashimoto, T. (1961). Influence of inorganic nitrogenous compounds on tobacco seed germination induced by gibberellin A3, kinetin and ammonium salts of organic acids. Plant and Cell Physiology, 2, 463-469.
6. Hashimoto, T. and Yamaki, T. (1960). Comparative effectiveness of gibberellins A1, A2, A3 and A4, with special reference to that of A4. The Botanical Magazine, Tokyo, 73, 64-68.
7. Hashimoto, T. and Yamaki, T. (1962). Interaction of GA and inorganic phosphate in tobacco seed germination. Plant and Cell Physiology, 3, 175-187.
8. Holdsworth, M. (1972). Phytochrome and seed germination. New Phytologist, 71, 105-110.
9. Honing, J.A. (1930). Nucleus and plasma in the heredity of the need of light for germination in Nicotiana seeds. Genetica, 12, 441-468.
10. Kasperbauer, M.J. (1968). Dark germination of receiprocal hybrid seed from light-requiring and -indifferent Nicotiana tabacum. Physiologia Plantarum, 21, 1308-1311.
11. Kasperbauer, M.J. (1968). Germination of tobacco seed. I. Inconsistency of light sensitivity. Tobacco, 166, 24-26. (From Field Crop Abstracts, 1969, 22, 1436.)
12. Krishnamoorthi, T. and Moses, J.S.L. (1969). Breaking of seed dormancy in tobacco (Nicotiana tabacum L.). Indian Journal of Agricultural Science, 39, 1098-1101.
13. Manolov, A.J. (1957). Breaking dormancy of tobacco seeds. Izv. Inst. Biol. Met. Popov, Ban. 8, 83-98. (From Horticultural Abstracts, 1959, 29, 2610.)
14. Mayer, A.M. and Poljakoff-Mayber, A. (1963). The germination of seeds. Pergamon Press.
15. Ogawara, K. and Ono, K. (1955). Effects of various nitrogen compounds and respiratory intermediates on the germination of the light-favored tobacco seeds. Bulletin of School of Education, Okayama University, 1, 97-104.
16. Ogawara, K. and Ono, K. (1961). Interaction of gibberellin, kinetin and potassium nitrate in the germination of light-sensitive tobacco seeds. Plant and Cell Physiology, 2, 87-98.
17. Popov, M. (1962). Breaking post-harvest physiological dormancy in tobacco seeds. Bâlg. Tjutjun, 7, 52-54. (From Horticultural Abstracts, 1963, 33, 7695.)
18. Rajarao, D.C. (1970). Recent trends of the research on the factors influencing the germination of tobacco seed. Rajahmundri (India): Central Tobacco Research Institute, 15pp. (From Field Crop Abstracts, 1970, 23, 3963.)
19. Roman, T. and Michlewska, C. (1964). [Further studies on the influence of some chemical compounds on the germination of tobacco seeds.] Biul. Centr. Lab. Przem. Tyton., Krakow, 3, 13-19. (From Field Crop Abstracts, 1969, 20, 577.)
20. Sarma, C.M. and Phukan, J.D. (1981). Synergism between gibberellic acid and potassium nitrate on the germination of positively photoblastic seeds of tobacco. Indian Agriculturist, 25, 221-226.
21. Schmidt, B. (1963). [Physiology of germination and methods of assessing the germinative power of tobacco seeds.] Dtsch. Tabakbau, 43, 9-10. (From Horticultural Abstracts, 1964, 34, 1195.)
22. Schmidt, B. (1964). [Investigation on the germination capacity of tobacco seed.] Landw. Forsch., 17, 17-22. (From Horticultural Abstracts, 1964, 34, 7245.)
23. Spaulding, D.W. and Steffens, G.L. (1969). Elimination of light requirements for tobacco seed germination with gibberellic acid, indole-3-acetic acid and N6-benzyladenine. Tobacco Science, 13, 156-159.
24. Takahashi, N., Moroo, T., Hashimoto, T. and Yamaki, T. (1962). Effects of some organic acids on the dark germination of tobacco seed. The Botanical Magazine, Tokyo, 75, 163-169.
25. Takahashi, N., Yamada, T., Hashimoto, T. and Yamaki, T. (1962). Effect of inorganic compounds on the dark germination of tobacco seeds induced by gibberellin. The Botanical Magazine, Tokyo, 75, 49-55.
26. Takahashi, N., Yamada, T., Moroo, T. and Yamaki, T. (1962). Further studies upon the effect of inorganic compounds on the dark germination of tobacco seeds induced by gibberellin. The Botanical Magazine, Tokyo, 75, 83-91.
27. 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.
28. Tramvalidis, C. and Sideris, E.G. (1978). The effect of red light illumination on the germination of seeds from four oriental varieties of Nicotiana tabacum L. Bulletin d'Information Coresta, 50.
29. Watanabe, N. (1980). [Genetical studies on the photoblastism of tobacco seed.] Research Bulletin of the Faculty of Agriculture, Gifu University, 44, 1-34. (From Seed Abstracts, 1981, 4, 2676.)
30. Yamaki, T. and Takahashi, N. (1962). Some considerations upon the dark germination of tobacco seed. The Botanical Magazine, Tokyo 75, 245-254.
SOLANUM
|
S. acaule Bitt. [S. depexum Juz. &
Buk.] |
|
|
S. aviculare Forst. |
|
|
S. caldasii |
|
|
S. canasense Hawk. |
|
|
S. capsicastrum Link |
|
|
S. carolinense L. |
horsenettle |
|
S. chacoense Bitt. [S. schickii Juz. &
Buk.] |
|
|
S. chacoense Bitt. x S. emmeae Juz. &
Buk. |
|
|
S. chancayense |
|
|
S. chomatophilum |
|
|
S. demissum Lindl. |
bittersweet |
|
S. dulcamara L. |
|
|
S. garciae |
|
|
S. giganteum Jacq. |
|
|
S. guerreroense x S. isopetalum |
igbagba |
|
S. incanum L. |
|
|
S. jamesii Torr. |
|
|
S. khasianum Clarke |
|
|
S. laciniatum Ait. |
|
|
S. marginatum L. |
|
|
S. medians |
|
|
S. melongena L. |
aubergine, brinjal, eggplant, melongene |
|
S. multidissectum |
|
|
S. nigrum L. |
common nightshade |
|
S. papita Rydb. |
|
|
S. parodii |
|
|
S. phureja Juz. & Buk. |
|
|
S. pinnatisectum Dunal x S. jamesii
Torr. |
|
|
S. rostratum |
buffalo bur |
|
S. sarrachoides Sendt. |
|
|
S. schickii |
|
|
S. stenotomum Juz. & Buk. |
|
|
S. stoloniferum Schlecht. |
|
|
S. tarijense |
|
|
S. tlaxcalense |
|
|
S. trifidum Correll. x S. jamesii
Torr. |
|
|
S. tuberosum L. |
potato |
|
S. verrucosum Schlecht. |
|
|
S. viarum Dunal |
|
|
S. xanthocarpum Schrad. & Wendl. |
|
|
S. yabari |
|
I. Evidence of dormancy
Seeds extracted from freshly harvested berries of S. tuberosum may show deep dormancy (5,6,9,13,16,18,19,21,34,35,36,38,40-42,44-46) which results in serious problems for breeders (18,19,42,45). Moreover, seeds of tetraploids can be more dormant than seeds of diploids (36). Claims of immediate germination of freshly harvested seeds (28) are somewhat exaggerated. Although many seeds germinate relatively quickly, other seeds continue to germinate after 90 days in test (28).
At room temperature after-ripening periods of several weeks (9), 2-3 months (13,40), 3-5 months (45), 6 months to 2 years (36) or more than a year (44) have been reported to be necessary before dormancy is lost. At lower temperatures (0°-5°C) dormancy may be maintained for between 5 (39) and 13 years (5).
Seeds of other tuber-bearing Solanum spp. - and their hybrids - may show considerably more dormancy (2,16,36,37,40). Thus, for example, seeds of S. chancayense, S. medians, S. multidissectum and S. pinnatisectum stored at 1°-3°C with 5% moisture content continued to lose dormancy after more than 10 years in storage (56). In addition it should be noted that secondary dormancy has been reported in S. chacoense, S. demissum, S. tarijense, S. tuberosum and S. verrucosum (37,39).
Dormancy has also been reported in seeds of the cultivated S. melongena (24,26,27,54,60), other non-tuber bearing Solanum spp. which provide vegetables or pharmaceuticals, viz. S. acaule (20), S. dulcamara (32), S. incanum (15), S. khasianum (4,17,23), S. laciniatum (11,30,49), S. nigrum (33,58,59), and S. xanthocarpum (29,59), and the weed species S. carolinense (55) and S. sarrachoides (31).
II. Germination regimes for non-dormant seeds
S. capsicastrum
TP; BP: 20°/30°C (16h/8h); 20°C: 28d (ISTA)
S. carolinense, S. dulcamara
Constant temperatures: 30°C (43)
Alternating temperatures: 20°/30°C (16h/8h) (43)
S. giganteum
TP; BP: 20°/30°C (16h/8h); 20°C: 28d (ISTA)
S. laciniatum
TP: 20°/30°C (16h/8h); 20°C: 28d (ISTA)
S. marginatum
TP; BP: 20°/30°C (16h/8h); 20°C: 28d (ISTA)
S. melongena
TP; BP: 20°/30°C (16h/8h): 14d (AOSA,ISTA)
Constant temperatures: 15°-25°C (3)
S. nigrum, S. rostratum
Constant temperatures: 30°C (43)
Alternating temperatures: 20°/30°C (16h/8h) (43)
Solanum spp.
TP: 20°/30°C (16h/8h): 14d (AOSA)
III. Unsuccessful dormancy-breaking treatments
S. aviculare
Constant temperatures: 15°-25°C, dark (62)
Pre-chill: 4°C, 1-10w (62)
GA3: pre-applied, 24h, 10-2, 10-5 M (30); pre-applied, 72h, 10-2 M (30); pre-applied, 72h, 10-2 -10-5 M, dissolved in acetone (30)
Scarification: concentrated sulphuric acid, 5-60 min (30); mechanical, air turbine scarifier, 1h (30) Acetone: pre-applied, 24h (30)
S. carolinense
Light: 1500 lux, 8h/d, at 20°/30°C (16h/8h) (55)
Ethylene: co-applied, 1, 10, 100 ppm, at 20°/30°C (16h/8h) (55)
S. dulcamara
Constant temperatures: 15°C, 20°C, 25°C (32)
S. khasianum
Light: continuous (23); dark (17,23)
Ammonium nitrate: pre-applied, 24h, 0.1, 0.5, 1% (23)
Scarification: sulphuric acid, 80%, 5 min, then pre-soak, 16h, germinate at 25°C in dark, with or without either potassium nitrate, pre-applied, 16h, 1%, or thiourea, pre-applied, 16h, 1% (17)
S. laciniatum
Constant temperatures: 10°C, 40°C (11); 15°-30°C, dark (62)
Pre-chill: 4°C, 1-10w (62)
Potassium nitrate: pre-applied, 24,48h, 0.1-0.3% (49); pre-applied, 3,6d, 1, 3, 55% (49)
Thiourea: co-applied, 1% (30)
GA3: pre-applied, 24h, 10-4, 10-5 M, dissolved in acetone (30); pre-applied, 72h, 10-2 M (30); pre-applied, 24,48,72h, 0.01, 0.1, 1 ppm (49); pre-applied, 9d, 500-1500 ppm (49)
Cytokinin: co-applied, 5x10-7 -5x10-5 M (30)
Indoleacetic acid: pre-applied, 24-72h, 0.001-0.1 ppm (49)
Pre-wash: 1-5d (49)
Storage: 1,2,3d, -5°-35°C (49)
Scarification: concentrated sulphuric acid, 5-60 min (30); mechanical, air turbine scarifier, 1h (30)
S. melongena
Constant temperatures: 9°-16°C (60); 20°C, 25°C (54); 25°C (24,27); 15°C, 20°C, 25°C, light or dark (52)
Light: (25); continuous (52); infra red, 25°C (27); far red (52); blue (52)
Oxygen: 10-21% (52)
Carbon dioxide: (52)
S. nigrum
Constant temperatures: 4°-30°C (33); 21°C, light or dark (58); 10°C, 15°C, 40°C, 45°C in light, 10-4 mol m-2 s-1, 16h/d, or dark (61); 10°-45°C, dark (61)
Pre-soak: 12h (58)
Potassium nitrate: co-applied, 0.2% (33)
Light: green (33); dark (33); far red, 42 W m-2, 5 min (33); sunlight, 8h/d (59); red (59)
S. stenotomum
Alternating temperatures: 20°/30°C (18h/6h) (16)
GA3: co-applied, 1000, 2000 ppm (16)
S. tuberosum
Constant temperatures: 0°-10°C (46,47); 25°C, 30°C (42); 30°C, diffuse light (6); 30°C, 35°C (46,47)
Alternating temperatures: 20°/30°C (18h/6h) (16)
Pre-chill: 0°-5°C, 3d (46); 5°C, 7d, with or without potassium nitrate, co-applied, 0.2% (42); 3°-5°C, 7-21d, germinate at 20°/30°C (16h/8h) (6)
Pre-soak: 24h (19); 48h (36,46)
Pre-dry: 72°C, to constant weight (46)
Storage: -5°C, 2d (36); berries, 0°-5°C, 20°-23°C, 35d (46)
Light: continuous (1); 600-2500 fc, 16h/d (18); daylight, 4h/w (36); dark (36)
Potassium nitrate: co-applied, 0.2% (36); co-applied, 1% (42)
Thiourea: co-applied, 1% (42)
Coumarin: co-applied, 200 ppm (36)
Hydrogen peroxide: co-applied, 3% (46)
Scarification: concentrated sulphuric acid, 1 min (46); concentrated sulphuric acid, 1-5 min (42); sulphuric acid, 2, 5, 10, 25%, 45 min (45,46); sulphuric acid, 75%, 15-45 min (6)
Ethyl alcohol: pre-applied, 1h, 5-50% (45,46)
Ethylene chlorohydrin: pre-applied, 12h, 6% (45,46)
Thiram: dust, 75% (19)
S. xanthocarpum
Constant temperatures: 20°C, 25°C, 35°C, light, 5-6h/d (59)
Light: daylight, 8-24h/d (59); dark, continuous (59); red (59)
IV. Partly-successful dormancy-breaking treatments
S. acaule
GA3: co-applied, 500 ppm (20)
S. aviculare
Constant temperatures: 25°C in light (62)
Alternating temperatures: 20°/30°C (16h/8h) (62)
GA3: pre-applied, 24h, 10-3, 10-4 M (30); pre-applied, 24h, 10-2-10-5 M, dissolved in acetone (30); pre-applied, 72h, 10-3-10-5 M (30)
Pre-soak: 1,3d (30)
S. caldasii
Potassium nitrate: co-applied, 0.2-1% (41)
Scarification: sulphuric acid, 30%, 6-14 min (41)
S. canasense
GA3: co-applied, 500 ppm (16)
S. chomatophilum
GA3: pre-applied, 16h, 1500 ppm (2)
Pre-soak: 16h (2)
Pellet: in charcoal with or without GA3, 1500 ppm (2)
S. dulcamara
Constant temperatures: 30°C, daylight, short period (32)
GA4/7: co-applied, 300 ppm, at alternating temperatures (32)
S. guerreroense x S. isopetalum
Pre-soak: 16h (2)
Pellet: in charcoal (2)
GA3: pre-applied, 16h, 1500 ppm (2)
S. incanum
Alternating temperatures: 10°/25°C (8h/16h) (15)
Removal of seed covering structures: (15)
GA3: pre-applied, 1,6d, 10°C, 25°C, 500 ppm, then pre-dry (15)
Pre-dry: after imbibition, 1,6d, 10°C, 25°C (15)
S. jamesii
GA3: pre-applied, 24h, 2000 ppm (40)
S. khasianum
Pre-soak: 4h (4); 16h, germinate at 25°C in light (17)
Light: (17); diffuse (23)
Potassium nitrate: pre-applied, 16h, 1%, to scarified seeds, sulphuric acid, 80%, 5 min, germinate at 25°C in light (17)
Ammonium nitrate: pre-applied, 24h, 0.125%, diffuse light (23)
Thiourea: pre-applied, 16h, 1%, to scarified seeds, sulphuric acid, 80%, 5 min, germinate at 25°C in light (17)
Ethrel: pre-applied, 4h, 500-1250 ppm (4)
S. laciniatum
Alternating temperatures: 15°/25°C, 20°/30°C (16h/8h), dark (62)
Pre-soak: 1,3d (30)
GA3: pre-applied, 24h, 10-2, 10-5 M (30); pre-applied, 72h, 10-3-10-5 M (30); pre-applied, 3,6d, 500-1500 ppm (49); co-applied, 1000 ppm (11)
Potassium nitrate: pre-applied, 3d, 0.1-0.3% (49); pre-applied, 9d, 1, 3, 55% (49)
Acetone: pre-applied, 1d (30)
S. melongena
Constant temperatures: 23°-26°C (60)
Alternating temperatures: 30°/20°C (16h/8h) (52,54); 30°/15°C (16h/8h) (24,27)
Warm stratification: 20°C, 1-5d, then 10°C, 15°C, 25°C, 30°C, 2h, germinate at 30°/20°C (16h/8h) (54); 25°C, 1-6d, then 5°C, dark, 2-8h, germinate at 25°C, dark (53); 25°C, 1-6d, then 35°C, dark, 4h, germinate at 25°C, dark (53); 40°C, 45°C, 7d, plus GA3, co-applied, 100 ppm, germinate at 25°C, dark (51)
Light: short exposure (51,52); red, low temperatures (52); dark, alternating temperatures (52)
Potassium nitrate: co-applied, 0.2%, germinate at 25°C or 30°/15°C (16h/8h) (24,27)
GA3: co-applied, 25, 50 ppm, at 30°/20°C (16h/8h) (54); co-applied, 50, 100 ppm, at 25°C, 30°/15°C (16h/8h) (24,27); co-applied, 100 ppm, at 20°C, 25°C, 30°C, 35°C, dark or light (51)
S. nigrum
Constant temperatures: 15°C, light (59); 20°C, light, 10-4 mol m-2 s-1, 16h/d (61)
Alternating temperatures: 10°-15°/25°C (16h/8h) in light (33); 25°/9°C (16h/8h) (58); 20°/30°C, 15°/30°C (16h/8h) (59)
Pre-chill: 3°-5°C, 1-6w (58)
Warm stratification: 30°C, 1-10w (33)
Light: diffuse daylight, 4-8h/d (59); direct sunlight, 2-6h/d (59); plus aerated water (59)
S. parodii
Potassium nitrate: co-applied, 0.2-1% (41)
Scarification: sulphuric acid, 30%, 6-14 min (41)
S. pinnatisectum x S. jamesii
GA3: pre-applied, 24h, 2000 ppm (40)
S. sarrachoides
Alternating temperatures: 10°/25°C, 10°/30°C, 20°/30°C (16h/8h) (31)
S. stenotomum
Constant temperatures: 10°C, 20°C (16)
Alternating temperatures: 10°/30°C (18h/6h) (16)
Pre-chill: 5°-10°C, 7d (16)
GA3: co-applied, 500 ppm (16)
Potassium nitrate: co-applied, 0.2% (16)
Light: (16)
S. tuberosum
Constant temperatures: 7°C, 10°C, 20°C, continuous light (1); 10°C in light (16); 15°C, 20°C (42); 12°C, 20°C, 25°C, diffuse light (6)
Alternating temperatures: 10°/30°C, 12°/20°C, 20°/12°C (18h/6h) (16); 20°/30°C (16h/8h) (42); 12°/20°C, 20°/30°C (17h/7h) (6)
Pre-chill: 5°-10°C, 7d (16); 0°C, 5°C, 55d (46)
Warm stratification: 30°C, 45d, germinate at 20°C (47); 30°C, 3w, diffuse light, germinate at 20°/30°C (17h/7h) (6)
Light: (16); 1200 fc, 4,8h/d (18); 600 fc, 16h/d (18); diffuse daylight (36)
Potassium nitrate: co-applied, 0.2% (16,42); co-applied, 0.2-1% (41); pre-applied, 24h, 0.2-2% (6)
GA3: co-applied, 500, 1000, 2000 ppm (16); co-applied, 0.5, 5 ppm, at 20°C in light, 1200 fc, 16h/d (18); co-applied, up to 200 ppm, plus cysteine, co-applied, 1780 ppm (36); pre-applied, 16h, 1500 ppm (2)
Pre-soak: 24h (6)
Removal of seed covering structures: (36,45,46)
Scarification: concentrated sulphuric acid, 1 min (45); sulphuric acid, 30% 6-14 min (41); sulphuric acid, 20, 25, 30%, 5, 10 min (41); concentrated sulphuric acid, drip (41); sand paper (45)
S. verrucosum
GA3: pre-applied, 24h, 2000 ppm (40)
S. viarum
Constant temperatures: 30°C (57)
Acetic acid: pre-applied, 2%, germinate at 30°C (57)
S. xanthocarpum
Alternating temperatures: 20°/25°C, 25°/30°C, 30°/35°C, 35°/40°C (16h/8h), daylight, 5-6h/d (59)
Light: daylight, 2-3h/d (59); plus aerated water (59)
S. yabari
Scarification: concentrated sulphuric acid, drip (41); sulphuric acid, 20, 25, 30%, 5, 10 min (41)
V. Successful dormancy-breaking treatments
S. acaule
GA3: co-applied, 500 ppm (16)
S. aviculare
Alternating temperatures: 15°/25°C (16h/8h), light (62)
Acetone: pre-applied, 72h (30)
S. capsicastrum
Light, Potassium nitrate (ISTA)
S. carolinense
Potassium nitrate: co-applied, 0.2%, at 30°C or 20°/30°C (16h/8h) (43)
S. chacoense
GA3: co-applied, 500 ppm (16); pre-applied, 24h, 2000, 4000 ppm (40)
Removal of seed covering structures: (41)
S. chacoense x S. emmeae
GA3: pre-applied, 24h, 2000, 4000 ppm (40)
S. demissum
GA3: co-applied, 250 ppm, plus cysteine, 900 ppm, co-applied (36); pre-applied, 24h, 1000, 2000, 4000 ppm (40)
S. dulcamara
Alternating temperatures: 10°/25°C, 10°/30°C, 20°/30°C (16h/8h) (32)
Pre-chill: 4°C, 1m (32)
Potassium nitrate: co-applied, 0.2%, at 30°C or 20°/30°C (16h/8h) (43)
GA4/7: co-applied, 300 ppm, at 20°C, 25°C or 30°C (32)
S. garciae
Removal of seed covering structures: (41)
S. giganteum
Light, Potassium nitrate (ISTA)
S. guerreroense x S. isopetalum
Pellet: in charcoal with GA3, 1500 ppm (2)
S. khasianum
GA3: pre-applied, 16h, 1%, to scarified seeds, sulphuric acid, 80%, 5 min, germinate at 25°C in light (17)
S. laciniatum
Potassium nitrate (ISTA)
Constant temperatures: 22°C, 30°C (11); 28°C (14)
Alternating temperatures: 15°/25°C (16h/8h), light, 8h (62)
Pre-chill: 4°C, 3w, germinate at 26°C (30)
GA3: pre-applied, 24h, 10-3, 10-4 M, germinate at 26°C (30); pre-applied, 24h, 10-2, 10-3 M, dissolved in acetone, germinate at 26°C (30)
Thiourea: co-applied, 0.01-0.75%, at 26°C (30)
Acetone: pre-applied, 72h, germinate at 26°C (30)
S. marginatum
Light, Potassium nitrate (ISTA)
S. melongena
Potassium nitrate, Light (AOSA)
Alternating temperatures: 20°-23°/30°C, 28°-30°/20°±3°C (16h/8h) (60)
GA3: co-applied, 50, 100, 200 ppm, at 30°/20°C (16h/8h) (50,54); pre-applied, 24h, 10-40 ppm (12)
Indoleacetic acid: pre-applied, 24h, 10, 20 ppm (12)
1-Naphthaleneacetic acid: pre-applied, 24h, 10-40 ppm (12)
Polyethylene glycol: pre-applied, 14d, at 15°C (25)
S. nigrum
Constant temperatures: 25°C, 30°C, 35°C in light, 10-4 mol m-2 s-1 (61)
Alternating temperatures: 10°/30°C, 15°/30°C (16h/8h) in light (33); 15°-20°/25°C (16h/8h) in dark or light, 8h/d (59); 20°/30°C (16h/8h) (43)
Pre-chill: 4°C, 1-10w (33)
Warm stratification: 15°C, 3-12d, daylight or red light, 5 min, 11.7 W m-2 (33)
Light: diffuse daylight, 8-14h/d, at 15°/25°C (16h/8h) (59); dark, continuous, at 15°/25°C (16h/8h) (59); green (59)
Potassium nitrate: co-applied, 0.2%, at 30°C or 20°/30°C (16h/8h) (43)
GA3: co-applied, 500 ppm (33); co-applied, 5x10-3 M, at 25°C, 35°C, light or dark (61)
GA4/7: co-applied, 10-4 M, at 25°C, 35°C, light or dark (61)
S. papita
GA3: co-applied, 500 ppm (16)
S. phureja
GA3: pre-applied, 24h, 2000 ppm (40)
S. rostratum
Potassium nitrate: co-applied, 0.2%, at 30°C or 20°/30°C (16h/8h) (43)
S. sarrachoides
Alternating temperatures: 4°/25°C (16h/8h) (31) Pre-chill: 4°C, 6m (31)
S. schickii
Removal of seed covering structures: (41)
S. stoloniferum
GA3: pre-applied, 24h, 1000 ppm (40)
S. trifidum x S. jamesii
GA3: pre-applied, 24h, 2000 ppm (40)
S. tlaxcalense
Removal of seed covering structures: (41)
S. tuberosum
Constant temperatures: 10°C (7); 10°C, discontinuous light (1); 20°C (46)
Warm stratification: 16°-18°C, 12d (22,48); 30°C, 55d (46)
GA3: pre-applied, 24h, 2000 ppm (8,9,19,21); pre-applied, 24h, 2000, 4000 ppm (40); co-applied, 50, 500 ppm, at 20°C in light, 1200 fc, 8h/d (18); co-applied, 300, 1000 ppm, plus cysteine, co-applied, 1780 ppm (36); co-applied, 250 ppm, plus cysteine, co-applied, 900 ppm (36)
Pellet: in charcoal with GA3, 1500 ppm (2)
Removal of seed covering structures: (9,10,41)
S. viarum
GA3: pre-applied, 12-18h, 1000 ppm (29)
S. xanthocarpum
Alternating temperatures: 25°/35°C (16h/8h) in light, 5-6h/d (59)
GA3: pre-applied, 12-18h, 1000 ppm (29)
S. yabari
Removal of seed covering structures: (41)
Solanum spp.
Light, Potassium nitrate (AOSA)
VI. Comment
The widely recognised ability of gibberellic acid to promote the germination of dormant seeds of Solanum spp. is apparent from this list of successful dormancy breaking agents - though it should also be noted that on occasion treatment with gibberellic acid may have no effect at all (16,30,49) - particularly when applied at low concentrations - or be only partly successful (15,16,18,20,27,30,36,40,54). In general pre-application is preferable to co-application. In the latter case high concentrations can result in abnormal seedling morphology.
The following general procedure is recommended for S. tuberosum: 2000 ppm GA3, pre-applied for 24 hours, with subsequent testing for germination at 20°C for 28 days in diffuse daylight or the light regime provided in Chapter 6. This procedure is sufficiently promotory for the majority of seed lots and does not result in the production of abnormal seedlings (21,A). Moreover, treatment with GA3 at this concentration does not appear to damage aged seeds (A). Extremely dormant seeds may require treatment with 4000 ppm GA3 (40).
Solanum collections are unlikely to be limited to S. tuberosum alone; rather they will contain very many Solanum spp. (e.g. see (56)). In general tuber-bearing Solanum spp. give higher germination at constant temperatures than at alternating temperatures (16,42). 20°C is suitable although sometimes 10°C may be preferable (1,7). Whichever constant temperature is used diffuse light is essential and treatment with GA3 recommended (as given for S. tuberosum).
In contrast non-tuber-bearing Solanum spp. tend to require alternating temperatures for full germination (15,24,27,31-33,43,54,58-61). For example, in S. melongena an alternating temperature regime of 29°-30°/23°C (8h/16h) was sufficient alone to provide suitable conditions for rapid (within 5 days) and almost complete germination of both fresh and 1 year old dormant seeds (60). Note that this alternating temperature regime is similar to that prescribed by AOSA and ISTA.
The following general procedure is suggested for non-tuber-bearing Solanum spp., but the GA3 treatment may not always be essential: 500-2000 ppm GA3 pre-applied for 24 hours or 10-3 -10-4 M GA3 co-applied at alternating temperature regimes of 20°/30°C, 30°/20°C, or 30°/15°C (16h/8h) either in diffuse light or the light regime given in Chapter 6.
VII. References
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