The Moraceae comprise more than 1000 species of trees and shrubs and, rarely, herbaceous plants and climbers which provide edible fruits (e.g. Artocarpus altilis (Park.) Fosber, breadfruit) and other products (e.g. Broussonetia papyrifera (L.) Vent., paper mulberry). The fruits are often compound and fleshy. Seed storage behaviour is generally orthodox (e.g. Ficus, Humulus, Morus), but some genera possess recalcitrant seeds (e.g. Artocarpus).
SEED DORMANCY AND GERMINATION
The seeds may or may not possess an endosperm. Seed dormancy can be a difficult problem to overcome and the seedcoats may also prevent germination in some accessions. Promotory treatments include pre-chilling, some disruption of the seed coat and light in germination tests. Detailed information is provided for seed dormancy and germination in the genera Ficus, Humulus and Morus in this chapter. Additional information on recommended germination test procedures and dormancy-breaking treatments is summarised in Table 48.1.
TABLE 48.1 Summary of germination test recommendations for species within the Moraceae
|
Species and Authority |
Substrate |
Temperature |
Durationo |
Additional directions |
Source |
|
Antidesma spp. |
|
|
21d |
pre-soak, 24h |
Riley |
|
Artocarpus heterophyllus Lam. |
S |
25°-30°C |
21d |
light, continuous |
CHML |
|
Artocarpus spp. |
|
|
21d |
pre-soak, 24h, then warm stratification |
Riley |
|
Cannabis sativa L.
|
TP; BP |
20°/30°C; 20°C |
7d |
|
ISTA |
|
BP |
20°/30°C |
7d |
|
AOSA |
|
|
BP; S |
20°/30°C |
7d |
|
Everson |
|
|
Cudrania tricuspidata
|
|
|
21d |
scarify, abrade with sharp sand, or file or nick seed |
Riley |
|
|
|
|
coat, then pre-chill, 1°-5°C, 30-60d |
|
FICUS
|
F. aurea Nutt. |
|
|
F. carica L. |
common fig |
|
F. populnea Willd. |
|
|
F. religiosa L. |
pipal-tree, bodh-tree, peepul |
|
F. roxburghii |
|
|
F. septica Burm. f. |
|
I. Evidence of dormancy
Seeds of F. carica are reported to germinate readily in glasshouse sowings (2,3,5,8), but full germination in laboratory tests is more difficult to achieve.
II. Germination regimes for non-dormant seeds
-
III. Unsuccessful dormancy-breaking treatments
F. aurea
Light: dark (1)
F. religiosa
Constant temperatures: 15°C (4); 25°C in dark (4)
Light: dark (4)
IV. Partly-successful dormancy-breaking treatments
F. roxburghii
Constant temperatures: 15°C, 20°C (9)
F. septica
Soil: in glasshouse (6)
V. Successful dormancy-breaking treatments
F. aurea
Potassium nitrate: co-applied, plus calcium nitrate, magnesium sulphate, and monobasic potassium phosphate (Knop's solution), at room temperature in light (1)
F. carica
Soil: in glasshouse or warm room (2,3,5,8)
Pre-soak: 24h (10)
F. populnea
Potassium nitrate: co-applied, plus calcium nitrate, magnesium sulphate, and monobasic potassium phosphate (Knop's solution), at room temperature in light or dark (1)
F. religiosa
Constant temperatures: 25°C in white light (4)
F. roxburghii
Constant temperatures: 25°C, 30°C, in soil (9)
Ficus spp.
Constant temperatures: 28°C in unsterilized vermiculite or on top of filter papers with bacterium added (7)
VI. Comment
Seeds of F. aurea and F. religiosa are reported to require light for germination (1,4), whereas seeds of F. populnea will germinate in light or dark (1). Seeds of F. religiosa are sensitive to drying out of the germination test substratum; germination is reduced if this occurs (4). It is suggested that seeds of Ficus spp. be tested for germination on top of filter papers at 25°C or 30°C in the light; the filter papers should not be allowed to dry out.
VII. References
1. Bessey, E.A. (1908). The Florida strangling figs. Annual Report, Missouri Botanic Garden, 19, 23-33.
2. Condit, I.J. (1947). The Fig Waltham, Massachusetts.
3. Eisen, G. (1901). The fig. USDA Division of Pomology Bulletin No. 9, 317 pp. (Cited by Condit, 1947.)
4. Galil, J. and Meiri, L. (1981). Drupelet germination in Ficus religiosa L. Israel Journal of Botany, 30, 41-47.
5. Pammel, L.H. and King, C.M. (1926). Studies on germination of trees and woody plants (continued). Proceedings of the Iowa Academy of Science, 33, 97-119.
6. Piatos, P., Knight, R.J. Jr. and Burditt, A.K. Jr. (1976). Seed production in an exotic Ficus species. Proceedings of the Florida State Horticultural Society, 88, 462-464.
7. Ramirez, W.B. (1976). Germination of seeds of New World Urostigma (Ficus) and of Morus rubra L. (Moraceae). Revista De Biologia Tropical, 24, 1-6.
8. Storey, W.B. (1975). Figs. In Advances in fruit breeding (eds. J. Janick and J.N. Moore), pp. 568-589. Purdue University Press, Indiana.
9. Zimmer, K. (1981). [Germination conditions for some rare ornamental plants.] Deutscher Gartenbau, 36, 863-869.
10. Riley, J.M. (1981). Growing rare fruit from seed. California Rare Fruit Growers Yearbook, 13, 1-47.
HUMULUS
|
H. lupulus L. |
hop |
I. Evidence of dormancy
It is reported to be difficult to germinate seeds of H. lupulus (2,4-6,8,9); typically only 15% of seeds may germinate in tests immediately after harvest (6,7).
II. Germination regimes for non-dormant seeds
Constant temperatures: 20°C (2,5,7,9)
Alternating temperatures: 15°/25°C, dark/light (16h/8h) (3)
III. Unsuccessful dormancy-breaking treatments
Constant temperatures: 6°-10°C, 66d (4); 6°-12°C (8); 15°-23°C (7); 20°C (9); 20°-25°C, 66d (4); 30°C (8)
Pre-chill: -2°C, 3,6d (5)
Warm stratification: 15°-23°C, 2-15d, then pre-chill, 5°C, 1w (7); 15°-23°C, 10d, then pre-chill, -12°C, 1-4w (7); 15°-23°C, 15d, then pre-chill, -12°C, 1,2w (7); 15°-23°C, 2,5d, then pre-chill, -12°C, 1-5w (7)
Pre-soak: 24h, then pre-chill, 4.4°C, 1w, with or without scarification (9)
Scarification: concentrated sulphuric acid, 3 min (5); concentrated sulphuric acid, 1,3,30 min (9); concentrated hydrochloric acid, 3 min (5); methyl alcohol, 3 min (5); acetone, 3 min (5); ether, 3 min (5); xylene, 3 min (5); shake, 3 min (5)
Ethylene chlorohydrin: pre-applied, 12h, to imbibed seeds (5)
GA3: pre-applied, 15 min, 50-4000 ppm (9); co-applied, 50, 100, 4000 ppm (9); co-applied, 50 ppm (8)
GA7: co-applied, 20 ppm (8)
Potassium nitrate: pre-applied, 15 min, 0.2% (9); co-applied, 0.2% (9)
Thiourea: pre-applied, 15 min, 2, 5% (9)
Hydrogen sulphide: pre-applied, 15 min (9); co-applied (9)
Hydrogen peroxide: co-applied (8)
Bis-cyclohexanoneoxalyldihydrazone: pre-applied, 15 min, 0.5% (9); co-applied, 0.5% (9)
Ethylenediaminetetracetic acid: pre-applied, 15 min, 1% (9); co-applied, 1% (9)
Malic acid: pre-applied, 15 min, 0.5% (9); co-applied, 0.5% (9)
Indoleacetic acid: co-applied, 15 ppm (8)
2-4,Dichlorophenoxyacetic acid: co-applied, 20 ppm (8)
Ultrasonics: 5-240s, dry seeds (8)
Sulphuric acid: co-applied, 0.05, 0.5% (9)
Dimethylglyoxime: pre-applied, 15 min, 0.1% (9); co-applied, 0.1% (9)
Removal of seed covering structures: prick (8)
IV. Partly-successful dormancy-breaking treatments
Alternating temperatures: -2°/22°C (6d/1d), 42d (5); 2°/-2°C (7d/7d), 42d (5); 20°-25°C/6°-10°C (1d/1d, 3d/3d, 5d/5d) (4); 6°-10°C/20°-25°C (3d/3d, 5d/5d) (4)
Pre-chill: -2°C, 9, 12d (5); -2°C, 6w (5); 2°C, 6w (5); -9.5° to -1°C, 6w (5); 0°-1°C, 21,42d (8); 1°-3°C, 21-56d (8)
Warm stratification: 15°-23°C, 5-15d, then pre-chill, 5°C, 2-5w (7); 15°-23°C, 2d, then pre-chill, 5°C, 3-5w (7); 15°-23°C, 15d, then pre-chill, -12°C, 3-5w (7); 15°-23°C, 10d, then pre-chill, -12°C, 5w (7)
Pre-soak: 24h, then pre-chill, 4.4°C, 2-6w (9); 24h, then pre-chill, 4.4°C, 2-4w, then remove outer seed coat (9); 5d, 6°-10°C, germinate at 20°C or 25°C (3); 1°-3°C (8)
Thiourea: co-applied, 2, 5% (9)
Removal of seed covering structures: chip (4,9); operculum (6); operculum, then pre-chill, 0°C, 16-72d (6)
Scarification: concentrated sulphuric acid, 6-15 min (9); concentrated sulphuric acid, 10 min, then pre-chill, 4.4°C, 2w (9); sandpaper (9)
V. Successful dormancy-breaking treatments
Pre-chill: 0°C, 10d, then scarify, sandpaper (1); 2°C, 8-10w (5); 2°-3°C, 6-8w, germinate at 15°/25°C, dark/light (16h/8h) (3); 2°-10°C, 6w (5)
Pre-soak: 24h, then pre-chill, 4.4°C, 5-6w (2); 24h, then pre-chill, 4.4°C, 5-6w, then remove outer seed coat, germinate at 20°C (9)
Removal of seed covering structures: seed coat (8); chip, germinate at 6°-10°/20°-25°C (5d/5d), 37d (4); chip (8)
VI. Comment
Pre-chilling at 0°-5°C for between 5 and 10 weeks (2,3,5,9) is required to promote full germination of dormant seeds. Although scarification treatments can be promotory, they fail to promote full germination in the more dormant seeds, although they may reduce the duration of pre-chill treatment required to promote full germination. It is suggested that seeds of H. lupulus be pre-chilled at 3°-5°C for 6 weeks, and then tested for germination at 15°/25°C (16h/8h) with light applied during the period spent at the higher temperature (3). The seed coats of seeds which fail to begin to germinate within a week or so can be chipped or rubbed with sand paper; this should result in more rapid, uniform and complete germination (1,4,8,9).
VII. References
1. Bressman, E.N. (1931). Developing new varieties of hops. Science, 74, 202-203.
2. Burgess, A.H. (1964). Hops. Botany, cultivation and utilization. Leonard Hill, London.
3. Haunold, A. and Zimmermann, C.E. (1974). Pollen collection, crossing and seed germination of hop. Crop Science, 14, 774-776.
4. Holubinsky, I.N. (1941). Influence of temperature alternation on the germinable power of hop seeds (Humulus lupulus L.). Comptes Rendus (Doklady) de l'Académie des Sciences de l'URSS, 32, 85-86.
5. Keller, K.R. (1953). Seed germination in hop, Humulus lupulus L. Agronomy Journal, 45, 146-150.
6. Paine, J. (1950). The treatment of hop seed to improve germination. East Malling Research Station Report, 139-140.
7. Smith, D.C. (1939). Influence of moisture and low temperature on the germination of hop seeds. Journal of Agricultural Research, 58, 369-381.
8. Suciu, T., Salontai, A., Muntean, L., Felecan, V. and Vaida, L. (1977-1978). Recherches concernant la germination des semences de houblon (Humulus lupulus L.). Institutum Agronomicum "Dr. Petru Groza" Cluj-Napoca (Romania) Notulae Botanicae Horti Agrobotanici, 9, 79-83.
9. Williams, I.H. and Weston, E.W. (1958). Hop propagation. The germination of hop seeds. Annual Report 1957, Department of Hop Research, Wye College, 108-118.
MORUS
|
M. alba L. |
white mulberry |
|
M. alba var tatarica Loud. [M. tatarica
L.] |
Russian mulberry |
|
M. indica L. |
mulberry |
|
M. latifolia var rotundiloba |
mulberry |
|
M. Lhou (Ser.) Koidz. |
mulberry |
|
M. nigra L. |
black mulberry |
|
M. rubra L. |
red or American mulberry |
I. Evidence of dormancy
Although viviparous germination has been reported in seeds of M. latifolia var rotundiloba (4), dormancy can be exhibited in freshly harvested seeds of M. alba (3) and M. Lhou (7,8,9). At room temperature 2 years dry storage (over calcium chloride) is required to remove dormancy from the latter species (7).
II. Germination regimes for non-dormant seeds
Morus spp.
TP: 20°/30°C (16h/8h): 28d (ISTA)
III. Unsuccessful dormancy-breaking treatments
M. alba
Scarification: concentrated sulphuric acid, 15 min (3)
M. Lhou
Constant temperatures: below 21°C or above 39°C (8)
Light: indigo, violet, bluish-violet (8,9)
M. rubra
Sterile substratum: (5)
IV. Partly-successful dormancy-breaking treatments
M. alba
Pre-chill: 5°C, 90d (3)
M. alba var tatarica
Constant temperatures: 20°C (2)
Pre-chill: 1m (2)
M. indica
Pre-soak: 24h (6)
GA3: pre-applied, 24h, 10, 25 ppm (6)
Irradiation: gamma rays, 2500-15000 R (1)
M. Lhou
Constant temperatures: 24°-36°C in light or dark (8,9)
Light: diffuse, 700-680 nm, 560-520 nm (8,9)
M. nigra
Constant temperatures: 20°C (2)
Pre-chill: 1m (2)
V. Successful dormancy-breaking treatments
M. alba
Pre-chill: (11); 1°-5°C, 4-12w (10)
Scarification: abrade with sharp sand (11); file or nick seed coat (11)
M. alba var tatarica
Alternating temperatures: 20°/30°C in light (2)
M. indica
GA3: pre-applied, 24h, 50, 100 ppm (6)
M. Lhou
Constant temperatures: 32°C in light (7)
Sodium nitrate: pre-applied, 24h, 0.04% (8,9)
M. nigra
Alternating temperatures: 20°/30°C in light (2)
Pre-chill: (11); 1°-5°C, 4-12w (10)
M. rubra
Constant temperatures: 28°C, non-sterile substratum (5)
Alternating temperatures: 20°/30°C in light (2)
Pre-chill: (11)
Scarification: abrade with sharp sand (11); file or nick seed coat (11)
VI. Comment
Alternating temperatures (2) and light (2,8,9) are required for germination, although it is reported that the promotive effect of sodium nitrate is sufficient to avoid the requirement for light (8,9). It is suggested that the ISTA germination test procedure - 20°/30°C (16h/8h) in light - is satisfactory for all Morus spp., but if difficulties are encountered also co-apply 0.2% potassium nitrate and pre-chill for 4 to 12 weeks.
VII. References
1. Das, B.C. (1970). Effects of gamma radiation on germination and seedling development of mulberry. Science and Culture, 36, 60-61. (From Horticultural Abstracts, 1971, 41, 3312.)
2. Heit, C.E. (1969). Propagation from seed. Part 15: Fall plantings of shrub seeds for successful seedling production. American Nurseryman, 128, 8-10, 70-80.
3. Krefting, L.W. and Roe, E.I. (1949). The role of birds and mammals in seed germination. Ecological Monographs, 19, 269-286.
4. Mukherjee, S.K. (1960). Vivipary in mulberry. Science and Culture, 26, 234. (From Horticultural Abstracts, 1961, 31, 1986.)
5. Ramirez, W.B. (1976). Germaniation of seeds of New World Urostigma (Ficus) and of Morus rubra L. (Moraceae). Revista De Biologi Tropical, 24, 1-6.
6. Rao, L.S.P., Rao, T.P. and Narayanan, E.S. (1963). Response of mulberry seeds to gibberellic acid treatment. Current Science, 32, 348-349.
7. Takagi, I. (1939). [On the storage of mulberry seeds.] Research Bulletin of the Imperial Tokyo Sericultural College, 2, 1-22.
8. Takagi, I. (1940). [The effect of temperature and light on the germination of mulberry seeds.] Research Bulletin of the Imperial Tokyo Sericultural College, 2, 1-26.
9. Takagi, I. (1940). The effect of the temperature and the light conditions upon the germination of mulberry seed. Japanese Journal of Botany, 10, 73-74.
10. Gordon, A.G. and Rowe, D.C.F. (1982). Seed Manual for Ornamental Trees and Shrubs. Forestry Commission Bulletin 59, HMSO, London.
11. Riley, J.M. (1981). Growing rare fruit from seed. California Rare Fruit Growers Yearbook, 13, 1-47.
