ENVIRONMENTAL-FACTORS AFFECTING GERMINATION OF TROPICAL SODA APPLE (SOLANUM-VIARUM)

Laboratory studies were conducted to determine the effect of various f actors on germination of tropical soda apple. Tropical soda apple seed were found to be moderately photoblastic with 30% germination occurri ng in the dark. Germination increased in response to green (545 nm) an d red light (650 nm) to 75 and 66%, respectively, indicating phytochro me regulation. No germination occurred in response to blue (450 mn) an d far-red light (750 nm). Germination increased from 4 to 64% between 10 to 30 C, but no germination was found at 5 and 40 C. Maximum germin ation occurred at 30 C. A second degree polynomial (Y= -48.7 + 7.9X - 0.2X(2), R(2) = 0.76) best fit the data. Seed germinated over a broad range of pH (2 to 14) with the highest germination occurring at pH 8 a nd no germination occurring at pH 2 and 14 (Y = -63.3 + 30.5X - 1.9X(2 ), R(2) = 0.95). Seed germination declined as osmotic potential increa sed from 0 to -1.0 MPa (Y = 76.7 - 12.9X + 5.2X(2), R(2) = 0.87). Seed ling emergence was maximum from depth of 3 to 6 cm, but no seedling em ergence occurred when seed were planted below 12 cm (Y = 10.2 + 17.8X - 1.6X(2), R(2) = 0.93). Optimum germination occurred at a depth of 5. 6 cm. Mechanical and sulfuric acid scarification increased the rate of germination but not the overall percentage. Tap water or hot water in creased the rate of germination 26% and KNO3, GA(3), or ethephon incre ased it 53%. Tropical soda apple seed germinated in response to variab le environmental and edaphic conditions which could allow establishmen t in diverse ecosystems.