Introduction
Indian jujube is also known as ber. It is grown mainly for the edible fruits. The fruit is eaten fresh, dried, or canned. It is rich in minerals, such as iron, phosphorus, calcium, and in vitamins A and C. Leaves, bark, and roots are used for medicinal purposes. The wood is a valuable timber in making furniture. Indian jujube originated in India. Later it spread to Africa and Southeast Asia. It is commonly grown in China, India, Indonesia, Malaysia, Mozambique, Pakistan, the Philippines, Sri Lanka, and the West Indies.
Morphology
Indian jujube belongs to family Rhamnaceae and has chromosome num-ber 2n = 48. It is a small, thorny evergreen tree. Leaves are simple, alternate, and broadly oval. Flowers are small, greenish, hermaphrodite, and borne in clusters at the leaf axils. Fruit is ellipsoid to subglobose drupe, fleshy, and orange to brown in color with edible acidic pulp and a hard central stone.
The hard endocarp encloses one or two seeds.
Seed Storage
Seeds are predominantly used for propagation. They show orthodox stor-age behavior and maintain viability for fairly long periods under ambient conditions. However, unfavorable storage conditions reduce seed longev-ity. Seeds are also used for raising rootstocks for vegetative propagation by budding or grafting and in the conservation of genetic diversity.
Seed Collections
The Indian jujube grows well in hot, dry climates. High humidity and frost damage the crop, especially during the fruiting stage. It prefers deep, sandy loam soils. However, it withstands waterlogging and drought condi-tions. Plants are raised through seeds or patch budding. Honeybees cause pollination. Fruit takes four to five months to mature. Large healthy ripe fruits are used for seed purposes. Seeds are extracted, washed, dried, and suitably packed for storage.
Seed Germination
Seed germination is slow and uneven, owing to the hard endocarp. The seed is covered by the endocarp, which hardens after 50 days of bloom, and the testa turns to dark brown 100 to 110 days after anthesis. Moisture content decreases to 30 percent at harvest. Immature seeds do not germinate, while treatment with benzyladenine or gibberellic acid (10 ppm) stimulates germi-nation (Kim and Kim, 1983). Seed germigermi-nation is low in fresh seeds but im-proves on soaking in water or in acid. Seed soaking in concentrated sulfuric acid for six minutes gave highest seedling emergence (Singhrot and Makhija, 1979). Casini and Salvadori (1980) reported that removal of the endocarp and treatment with gibberellic acid (400 ppm) improved germination, and seed with the endocarp intact germinated after scarification by immersion in con-centrated sulfuric acid.
Storage Conditions
Fresh seeds gave low germination (33 percent), even up to eight months of storage. Seedling vigor was high at the end of the storage period (Reddy and Murthy, 1990). Seed viability and vigor are retained with low-tempera-ture storage. About 50 to 60 percent of seeds were viable after ten years of storage at 5 and –20°C (Doijode, unpublished data). Seed viability im-proved in one-year-old seeds by soaking them in water for 48 h followed by four days’ stratification in moist sand (Kajal, 1983). Seed treatment with potassium dihydrogen phosphate (1 percent) improved germination in stored seeds (203 days after extraction) (Ghosh and Sen, 1988).
REFERENCES
Casini, E. and Salvadori, S. 1980. The germination of seeds of jujube (Zizyphus sativa). I. Effect of gibberellic acid on seeds with and without endocarp. Revista di Agricoltura Sub-Tropicale e Tropicale 74:39-47.
Ghosh, S.N. and Sen, S.K. 1988. Effect of seed treatment on germination, seedling growth and longevity of ber (Ziziphus mauritiana) seeds. South Indian Hort.
36:260-261.
Kajal, R.S. 1983. Studies on the effect of sowing depth, seed and budding treatment on germination and budling growth in ber (Zizyphus mauritiana). Thesis Abstr.
Haryana Agri. University 9:176.
Kim, Y.S. and Kim, W.S. 1983. Studies on germination of Zizyphus jujuba seeds at different stages of growth and development. South Korean Hort. 25:47-53.
Reddy, Y.N. and Murthy, B.N.S. 1990. Studies on germinability and seedling vigor at different intervals of seed storage in ber (Zizyphus mauritiana). Indian J. Hort.
47:314-317.
Singhrot, R.S. and Makhija, M. 1979. Vegetative propagation of ber (Zizyphus mauritiana). III. Effect of time of sowing and acid treatment on ber seed germi-nation and seedling performance. Haryana J. Hort. Sci. 8:168-172.
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Mulberry (Morus spp.)
Introduction
Mulberry is cultivated for the edible fruits in many parts of the tropics and subtropics. It is cultivated in Canada, China, India, Japan, and the United States. It belongs to family Moraceae. The different species include Morus alba, M. indica, M. latifolia, M. lhou, M. nigra, and M. rubra. The black M. nigra is well suited for higher altitudes in the tropics. Ripe fruits are eaten fresh as a dessert and also cooked as a vegetable. Tree is monoecious or dioecious, small, and with thin, ovate, serrate leaves that are often deeply lobed. Fruit bunch is syncarpous with many drupes, 2.5 to 5.0 cm long, and white, red, or pink in color. Seeds or cuttings are used for plant propagation.
Seed Storage
Seedling emergence is slow and nonuniform due to the presence of dor-mancy. Two years of dry storage over calcium chloride (CaCl2) removes the dormancy, especially in Morus alba (Takagi, 1939). Seed exposure to alternate temperatures of 20/30°C for 16/8 h promotes germination (Ellis, Hong, and Roberts, 1985). Further, seed irradiation with gamma rays (7.5 kilorad [kr]) improves the germination (Das, 1970).
Mulberry seeds show orthodox storage behavior and are short-lived un-der ambient conditions (Kasiviswanathan and Iyengar, 1970). High seed moisture is injurious to seed longevity, and viability is lost rapidly at room temperature (Gupta, 1988). Seeds stored in desiccators over CaCl2+ 20 per-cent H2O (water) or 43.8 percent H2SO4(sulfuric acid) remained viable for 14 years as compared to 4 months in control. The relative humidity in desic-cators was 48 percent, and seed moisture content was 4 percent (Takagi, 1939). Low-moisture seeds packed in moisture-proof containers at low tem-peratures retain viability for fairly long periods.
REFERENCES
Das, B.C. 1970. Effect of gamma radiation on germination and seedling develop-ment of mulberry. Sci. Cult. 36:60-61.
Ellis, R.H., Hong, T.D., and Roberts, E.H. 1985. Handbook of seed technology for gene banks. Rome: International Board for Plant Genetic Resources, Volume II, pp. 507-508.
Gupta, P. 1988. Viability of mulberry seeds during storage. Seed Res. 16:248-250.
Kasiviswanathan, K. and Iyengar, M.N.S. 1970. Effect of maturity of fruit, month of collection and storage on the viability of three varieties of mulberry seeds. In-dian J. Seric. 9:31-37.
Takagi, I. 1939. On the storage of mulberry seeds. Res. Bull. Tokyo Imp. Sericult.
2:1-22.