The Vitaceae comprise more than 500 species of woody vines, shrubs and small trees within 12 genera, some of which provide edible fruits (e.g. Vitis spp., grape, vine). The fruits are small berries and the seeds show orthodox storage behaviour.
SEED DORMANCY AND GERMINATION
Dormancy can be a considerable problem. Detailed information on seed dormancy and germination is provided in this chapter for the genus Vitis.
VITIS
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V. vinifera L. |
grape, wine grape |
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V. vulpina L. |
riverbank grape |
I. Evidence of dormancy
Freshly extracted seeds of Vitis spp. usually show a high proportion of dormant seeds. For example, in one study only two of eight seed lots gave more than 6% germination in control germination tests (4). Dormant seeds often require considerable treatment periods before they will germinate. For example, 3 months storage at room temperature (after-ripening) failed to break dormancy (16) and in another case 5 months storage was required to increase germination from 0% to 62% (12). In addition to V. vinifera, the information summarised for Vitis includes results from investigations with seeds of other, unspecified, Vitis spp. and hybrids between these species and V. vinifera: the AOSA methods are for V. vulpina.
II. Germination regimes for non-dormant seeds
TP: 20°/30°C (16h/8h): 28d (AOSA)
Constant temperatures: 25°-30°C (1); 20°C, 25°C (6)
III. Unsuccessful dormancy-breaking treatments
Constant temperatures: 20°-35°C (1); 20°C, 35°C (4)
Alternating temperatures: 20°/30°C (16h/8h) (4)
Warm stratification: 30°C, 2d, then 20°C (1); 18°C, 150d (15)
Storage: 21°-37°C, 3m (16); 0°C, room temperature, 3-12w (17)
Pre-soak: 24h, 27°-54°C (10); 20°C, 60°C, 20 min (17)
Pre-wash: 24h (17)
GA3: co-applied, 2, 20 ppm (1); 1000 ppm (6); pre-applied, 48h, 500, 1000, 2500 ppm (9); pre-applied, 48h, 1000 ppm, plus kinetin, 1000 ppm (9); pre-applied, 48h, 2000 ppm, plus kinetin, 2000 ppm (9); pre-applied, 48h, 1000 ppm, plus thiourea, 1% (9); pre-applied, 48h, 2000 ppm, plus thiourea, 2% (9); pre-applied, 48h, 1000-2500 ppm, then pre-chill, 5°C, 15d (9); pre-applied, 24h, 50 ppm (11); pre-applied, 24h, 50-2000 ppm (12, 13)
GA4/7: pre-applied, 24h, 100, 250, 1000 ppm (11)
GA13: pre-applied, 24h, 50, 250, 500, 1000 ppm (11)
Indoleacetic acid: pre-applied, 24h, 1-1000 ppm, germinate at 28°C (7); pre-applied, 24h, 50-500 ppm (13)
Kinetin: pre-applied, 24h, 5-200 ppm (13)
Benzyladenine: pre-applied, 8000 ppm (17)
Ethephon: pre-applied, 24h, 1-1000 ppm, germinate at 28°C (7)
Thiourea: pre-applied, 24h, 0.5-2% (12); pre-applied, 24h, 0.5-5% (13)
Succinic acid-2,2-dimethylhydrazide: pre-applied, 28h, 500 ppm (10)
Cyclocel: pre-applied, 28h, 500 ppm (10)
Indolebutyric acid: pre-applied, 28h, 100 ppm (10); pre-applied, 24h, 50-500 ppm (13)
Scarification: concentrated sulphuric acid, 15 min (14); sulphuric acid, 25%, 15 min (14); sulphuric acid, 75%, 15,60 min (14)
IV. Partly-successful dormancy-breaking treatments
Constant temperatures: 26°C (1)
Alternating temperatures: 5°/25°C, 10°/33°C, 15°/33°C, 20°/30°C (16h/8h) (1); 1°/30°C (16h/8h), 14d, then 20°C (1)
Warm stratification: 27°-36°C, 1,2d, then 20°C (1); 18°C, 30-120d (15); 18°C, 30,60d, then 5°C, 15,30d, germinate at 30°C in light, 12h/d (15)
Pre-chill: 1°C, 3-19m (1); 1°-5°C, 90-120d (2); 4°-5°C, 30-90d (3); 3°-5°C, 21d, germinate at 20°C (4); 1°-5°C, 3-15w (8); 5°C, 15d (9); 5°C, 15d, then GA3, pre-applied, 48h, 2000 ppm (9); 4°C, 6w (10); 5°C, 40-120d (12); 5°C, 40-90d, plus GA3, pre-applied, 24h, 50-2000 ppm (12); 1°-5°C, 30-75d (13); 1°-5°C, 30-75d, then GA3, pre-applied, 24h, 50-2000 ppm (13); 1°-5°C, 30-75d, then kinetin, pre-applied, 24h, 5, 25 ppm (13); 5°C, 3,4m (14); 5°C, 30-150d, germinate at 30°C in light, 12h/d (15); 1°-5°C, 3m (16); 0°C, 2-12w (17)
Scarification: disc, plus GA3, pre-applied, 24h, 1, 10, 100 ppm (10); rotating sand paper disc, hilar end, plus GA3, pre-applied, 10, 100 ppm (17)
GA3: co-applied, 200 ppm (1); pre-applied, 24h, 2000 ppm, germinate at 20°C (4); pre-applied, 48h, 1000-2500 ppm, then pre-chill, 5°C, 8-30d (9); pre-applied, 28h, 5000 ppm (10); pre-applied, 24h, 100-1000 ppm (11); pre-applied, 24h, 50-10000 ppm, germinate at 30°C in light, 12h/d (15); pre-applied, 24h, 50-10000 ppm, pre-chill, 5°C, 60d, then germinate at 30°C in light, 12h/d (15); pre-applied, 10, 100, 1000 ppm (17)
GA4/7: pre-applied, 24h, 50, 500 ppm (11)
GA13: pre-applied, 24h, 100 ppm (11)
Pre-wash: 4-16d (9)
Pre-soak: 24h (15)
Nitric acid: pre-applied, 15 min, 3.5-11% (1)
Storage: 1°-5°C, 120d (2); 4°-5°C, 60d (6); 18°-20°C, 5m (12); 5°C, 10-14w (12); 5°C, 10-14w, then GA3, pre-applied, 24h, 100-2000 ppm (12); 5°C, 10-14w, then thiourea, pre-applied, 24h, 0.5-2% (12)
Hydrogen peroxide: pre-applied, 24h, 1 M, germinate at 20°C (4); pre-applied, 1 M, then GA3, pre-applied, 24h, 2000 ppm, then pre-chill, 3°-5°C, 21d, germinate at 20°C, 25°C, 30°C, 20°/30°C, 20°/35°C (16h/8h) (4)
Kinetin: pre-applied, 24h, 1-1000 ppm, germinate at 28°C (7) Cyclic adenosine monophosphate: pre-applied, 24h, 1-100 ppm, germinate at 28°C (7)
Morphactin: pre-applied, 28h, 100 ppm (10)
Ethephon: pre-applied, 28h, 5000 ppm (10)
Ethrel: pre-applied, 24h, 5-200 ppm, germinate at 30°C in light, 12h/d (15); pre-applied, 24h, 50-200 ppm, then pre-chill, 5°C, 60d, then germinate at 30°C in light, 12h/d (15)
Thiourea: pre-applied, 24h, 0.25-5%, germinate at 30°C in light, 12h/d (15); pre-applied, 24h, 0.25-5%, then pre-chill, 5°C, 60d, germinate at 30°C in light, 12h/d (15)
Indolebutyric acid: pre-applied, 24h, 50-500 ppm, germinate at 30°C in light, 12h/d (15); pre-applied, 24h, 50-500 ppm, then pre-chill, 5°C, 60d, germinate at 30°C in light, 12h/d (15)
Indoleacetic acid: pre-applied, 24h, 50-500 ppm, germinate at 30°C in light, 12h/d (15); pre-applied, 24h, 50-500 ppm, then pre-chill, 5°C, 60d, germinate at 30°C in light, 12h/d (15)
V. Successful dormancy-breaking treatments
Pre-chill (AOSA)
Pre-chill: 5°C, 12w (5)
Warm stratification: 27°-33°C, 2d, then 20°C (1)
GA3: pre-applied, 8000 ppm (17)
Hydrogen peroxide: pre-applied, 24h, 0.5 M, then GA3, pre-applied, 24h, 1000 ppm, then pre-chill, 3°-5°C, 21d, germinate at 20°/30°C (16h/8h), 42d (4)
VI. Comment
The AOSA rules for V. vulpina suggest a 90-day pre-chill at 3° to 5°C. Plant breeders have used very long pre-chill treatment periods to break seed dormancy, but despite this have rarely been completely successful in promoting the germination of all dormant seeds. For example, a pre-chill treatment to seeds of 14 hybrid crosses at 5°C for 12 weeks resulted in a mean germination of only 40% in subsequent germination tests with a range of individual test results from 8% to 62% (16).
Consequently treatment with gibberellin has been used. Gibberellins are more effective in promoting the germination of dormant seeds of Vitis spp. than other growth substances (9), or various other chemicals (15), and GA3 is more reliable than either GA4/7 or GA13 (11), but - as the preceding sections illustrate - only treatments with very high GA3 concentrations have been successful (17) where GA3 is the only dormancy breaking treatment. Unfortunately high concentrations of GA3 influence subsequent seedling growth (11,13,17) - for example, producing abnormal seedlings - and cannot, therefore, be recommended for application in gene banks. The solution to this problem has been to combine treatment with GA3 with other treatments, the most common additional treatment being that of pre-chill. Treatment with GA3 before the pre-chill treatment is more effective than the pre-chill before treatment with GA3 (9, 15). Unfortunately, however, the GA3 concentrations required to promote germination in such combined treatments can result in the death of some seeds within accessions, for example at 2000 ppm (4). Consequently it is necessary to reduce the GA3 concentration and introduce a further dormancy-breaking treatment.
The following combination of treatments has been devised and found to be successful for promoting the germination of dormant seeds of Vitis spp. whilst at the same time is not damaging to the seeds: a 24-hour pre-treatment in 0.5 M hydrogen peroxide, a further 24 hour pre-treatment in 1000 ppm GA3, followed by a 21 day pre-chill treatment at 3°-5°C with subsequent testing of the seeds in a diurnal alternating temperature regime of 20°/30°C (16h/8h) for 42 days (4). Staff in gene banks are recommended to use this procedure.
In passing it is worth noting that a 12 hour cycle alternating temperature regime has been suggested for germination tests of grape seeds, viz. 20°/30°C (9h/3h) (1). There would appear to be no harm in using this regime, but neither does there appear to be any advantage of it compared to a diurnal alternation of 20°/30°C (16h/8h) (1). Thus it is recommended that the diurnal alternating temperature regime be used in preference to the 12 hour cycle.
VII. References
1. Balthazard, J. (1979). Contribution a l'amelioration de la germination des graines de vigne. Ph.D. Thesis, Dijon University.
2. Chadha, K.L. and Manon, V.N. (1968). Studies on germination of grape seed. 1. Effect of different type of after-ripening treatments on seed germination. Journal of Research, Ludhiana, 5, 212-219.
3. Chohan, G.S. and Dhillon, B.S. (1976). Seed dormancy and endogenous growth substances in Anab-e-Shahi grapes. Vitis, 15, 5-10.
4. Ellis, R.H., Hong, T.D. and Roberts, E.H. (1983). A note on the development of a practical procedure for promoting the germination of dormant seed of grape (Vitis spp.). Vitis, 22, 211-219.
5. Flemion, F. (1937). After-ripening at 5°C favors germination of grape seeds. Contributions from the Boyce Thompson Institute, 9, 7-15.
6. Forlani, M. and Coppola, V. (1977). Effetti della frigoconservazione, dell'acido gibberellico e della temperatura sulla germinazione dei vinaccioli di Vitis vinifera L. Rivista di Viticoltura e di Enologia, 30, 445-451. (From Seed Abstracts, 1978, 1, 1247.)
7. Forlani, M. and Coppola, V. (1978). Influenza di alcuni fitoregolatori e del c-AMP sulla germinazione dei vinaccioli della "Raboso Piave". Rivista di Viticoltura e di Enologia, 31, 99-104. (From Seed Abstracts, 1978, 1, 2778.)
8. Harmon, F.N. and Weinberger, J.H. (1959). Effects of storage and stratification on germination of Vinifera grape seeds. Proceedings of the American Society for Horticultural Science, 73, 147-150.
9. Kachru, R.B., Singh, R.N. and Yadav, I.S. (1972). Physiological studies on dormancy in grape seeds (Vitis vinifera var. Black Muscat). II. On the effect of exogenous applications of growth substances, low chilling temperature and subjection of the seeds to running water. Vitis, 11, 289-295.
10. Manivel, L. and Weaver, R.J. (1974). Effect of growth regulators and heat on germination of Tokay grape seeds. Vitis, 12, 286-290.
11. Pal, R.N., Singh, R., Vij, V.K. and Sharma, J.N. (1976). Effect of gibberellins GA3, GA4/7 and GA13 on seed germination and subsequent seedling growth in Early Muscat grape (Vitis vinifera). Vitis, 14, 265-268.
12. Randhawa, G.S. and Negi, S.S. (1964). Preliminary studies on seed germination and subsequent seedling growth in grapes. Indian Journal of Horticulture, 21, 186-196.
13. Randhawa, G.S. and Pal, N.C. (1968). Further studies on seed germination and subsequent seedling growth in grape (Vitis spp.) Indian Journal of Horticulture, 25, 148-158.
14. Scott, D.H. and Ink, D.P. (1950). Grape seed germination experiments. Proceedings of the American Society for Horticultural Science, 56, 134-139.
15. Selim, H.H., Ibrahim, F.A., Fayek, M.A., El-Deen, S.A.S. and Gamal, N.M. (1981). Effect of different treatments on germination of Romi red grape seeds. Vitis, 20, 115-121.
16. Singh, S.N. (1961). Germination of grape (Vitis vinifera L.) hybrid seeds by chilling. Current Science, 30, 62.
17. Yeou-Der, K., Weaver, R.J. and Pool, R.M. (1968). Effect of low temperature and growth regulators on germination of "Tokay" grapes. Proceedings of the American Society for Horticultural Science, 92, 323-330.
