The Ebenaceae comprise 300 species of trees and shrubs with very hard wood within about six genera, one of which provides edible fruits (Diospyros virginiana L., common persimmon). The fruit is generally a leathery or fleshy indehiscent berry with between one and ten seeds.
Seed storage behaviour was originally thought to be recalcitrant, but there is now considerable doubt about this classification in at least some species. Seed dormancy can be considerable, much of the problem being due to the seed covering structures. Detailed information is provided in this chapter for the genus Diospyros only. This information includes details of storage behaviour as well as dormancy and germination.
DIOSPYROS
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D. digyna |
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D. discolor Willd. |
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D. kaki L. f. [D. chinensis Blume] |
kaki, Japanese persimmon |
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D. lotus L. |
date-plum |
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D. marmorata R.N. Parker |
marblewood |
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D. melaxoxylon |
tendu |
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D. texana Scheele |
Texas persimmon |
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D. virginiana L. |
American persimmon, common persimmon |
I. Evidence of dormancy
Seeds of D. lotus and D. texana are reported to germinate readily (5,11). However, elsewhere seeds of D. melaxoxylon, D. kaki, D. virginiana, D. digyna, D. discolor, D. melaxoxylon and D. lotus are reported to show considerable dormancy (1-3,6,8,10,14,15). The seed covering structures are reported to be the main cause of dormancy, by hindering the absorption of water by the seeds (2,8). Prolonged pre-chilling is reported to induce dormancy in seeds of D. texana (13).
II. Germination regimes for non-dormant seeds
D. kaki
Constant temperatures: 30°C, 30d (10)
D. texana
Constant temperatures: 20°-30°C (5)
Alternating temperatures: 20°/30°C (16h/8h) (5)
D. virginiana
Alternating temperatures: 20°/30°C (night/day), 125d (2); 20°/30°C (16h/8h), light, fluorescent, 160 fc, 8h/d (9)
III. Unsuccessful dormancy-breaking treatments
D. marmorata
Pre-soak: 24,48,96h (15); hot water, 24,48,96h (15)
D. texana
Constant temperatures: 15°C, 40°C (5)
Alternating temperatures: 10°/20°C, 15°/25°C (16h/8h) (5)
Pre-chill: 5°C, 30-120d (13)
Scarification: concentrated sulphuric acid, 30-120 min (13); concentrated sulphuric acid, 30 min, then pre-chill, 5°C, 30-120d (13)
Light: 2x10-4 E m-2 s-1, 8h/d (5); dark (5)
D. virginiana
Scarification: acetone, 1h (3); concentrated sulphuric acid, 2h (3); concentrated sulphuric acid, 2h, then pre-chill, 3°-10°C, 2m (3)
IV. Partly-successful dormancy-breaking treatments
D. marmorata
Warm stratification: in fruit, room temperature, 10-15d, then extract seeds (15)
D. melaxoxylon
Pre-soak: 24h (1)
D. texana
Constant temperatures: 17.5°C, 32.5°C, 35°C (5)
Alternating temperatures: 25°/35°C (16h/8h) (5)
D. virginiana
Pre-chill: 3°-10°C, 6-18w (3)
Scarification: acetone, 1h, then pre-chill, 3°-10°C, 2m (3)
Pre-soak: 24h (9)
GA3: pre-applied, 24h, 100-400 ppm (9)
V. Successful dormancy-breaking treatments
D. digyna, D. discolor
Warm stratification: (14)
Hydrogen peroxide: pre-applied, 20 min, 3%, then pre-soak, 24h (14)
D. kaki
Pre-chill: 3°-5°C, 60d (6); 10°C, 120d (8); 0°-7°C, 1-6m (14)
Pre-soak: 2d, then pre-chill, 10°C, 120d (8); 30°C, 24h, then remove part of seed coat around radicle (10)
Scarification: file or abrade seed coat (14)
D. lotus
Pre-chill: 3°-5°C, 90d (6); 10°C, 120d (8)
Pre-soak: 2d, then pre-chill, 10°C, 120d (8)
Succinic acid: pre-applied, 48h, 0.1% (12)
D. texana
Constant temperatures: 20°-30°C (5)
Alternating temperatures: 20°/30°C (16h/8h) (5)
Pre-chill: 0°-7°C, 1-6m (14)
Scarification: file or abrade seed coat (14)
D. virginiana
Pre-chill: 90d (4); 3°-5°C, 60,90d (6); 10°C, 60-90d (8); 10°C, 60-90d, germinate at 20°/30°C, 60d (2); 0°-7°C, 1-6m (14)
Removal of seed covering structures: part of seed coat over radicle (2); file or abrade seed coat (14)
VI. Comment
Seeds of Diospyros spp. can be tested for germination on top of moist paper (5,9,10). Light has no apparent effect on germination, whereas germination is very sensitive to temperature (5). The seeds will germinate at constant temperatures between 20° and 30°C, but beyond this range germination is reduced considerably (5). An alternating temperature regime of 20°/30°C (16h/8h) is reported to be satisfactory for germination (2,5,9). In general pre-chilling the seeds breaks dormancy (2-4,6,8,14), except in one report where pre-chilling for between 30 and 120 days induced dormancy in seeds of D. texana (13).
It is suggested that intact seeds of Diospyros spp. be tested for germination on or between moist papers at 20°/30°C (16h/8h) for at least 4 months (2). However, filing the seed coat or removing the seed covering structures should enable this germination test duration to be reduced.
In the past D. dignya, D. discolor, some varieties of D. kaki, and D. virginiana have been reported to show recalcitrant seed storage behaviour (4,7,10,14). However, there is now strong evidence that seeds of D. texana and D. virginiana show orthodox seed storage behaviour (2,5,14). For example, seeds of D. virginiana can be dried to between 3 and 8% moisture content and stored safely at -20°C (14). Similarly seeds of some varieties of D. kaki can be dried to 15% moisture content and stored safely at 0°C, -5°C, -20°C, and -196°C (10).
VII. References
1. Ahmad, A. (1962). A preliminary report on germination of tendu seed. Pakistan Journal of Forestry, 12, 138-144.
2. Anonymous (1948). Diospyros virginiana L. Common persimmon. In Woody-plant Seed Manual, U.S.D.A. Forest Service, Miscellaneous Publication No. 654.
3. Aroreira, J.S. (1962). [On dormancy and seed storage of some fruit trees.] Experientiae, 2, 541-609.
4. Darrow, G.M. (1975). Minor temperate fruits. In Advances in fruit breeding (eds. J. Janick and J.N. Moore), pp. 269-284. Purdue University Press, Indiana.
5. Everitt, J.H. (1984). Germination of Texas persimmon seed. Journal of Range Management, 37, 189-192.
6. Gasanov, Z.M. (1968). [Investigations on new rootstocks for oriental persimmons.] Subtropicheskie Kul'tury, 5, 104-110. (From Horticultural Abstracts, 1969, 39, 5674.)
7. Harrington, J.F. (1972). Seed storage and longevity. In Seed Biology, Vol. III (ed. T.T. Kozlowski), pp. 145-245, Academic Press, New York.
8. Hartmann, H.T. and Kester, D.E. (1975). Plant Propagation: principles and practices, 567 pp. Prentice Hall Inc., New Jersey.
9. Hogg, N.J. and Orr, H.P. (1969). Effect of gibberellic acid on germination of seeds from selected native trees and shrubs. Plant Propagator, 15, 8-9.
10. Kotobuki, K. (1978). Seed storage of Japanese persimmon, Diospyros kaki. In Long term preservation of favourable germplasm in arboreal crops, pp. 36-42, Ibaraki-ken, Japan.
11. Massover, B.L. and Kirillova, G.L. (1973). [Rational methods for propagating persimmon in the Gissarskaya valley of Tadzhikistan.] Subtropicheskie Kul'tury, 6, 61-65. (From Horticultural Abstracts, 1975, 45, 1308.)
12. Mkervali, V.G. (1977). [Studies on the problem of artificial immunization of laurel and persimmon.] Subtropicheskie Kul'tury, 4, 93-95. (From Horticultural Abstracts, 1978, 48, 9430.)
13. Plowman, R.D. and Munson, R.H. (1983). Seed dormancy in Texas persimon (Diospyros texana Scheele). Plant Propagator, 29, 14-15.
14. Riley, J.M. (1981). Growing rare fruit from seed. California Rare Fruit Growers Yearbook, 13, 1-47.
15. Sharma, S.K. (1977). A further contribution to the study of nursery behaviour of Diospyros marmorata R.N. Parker (marblewood). Indian Forester, 103, 542-549.
