Tang and Loo (1940) first reported the induction of tetraploid soybeans by soaking day-old seedlings in 0.05 to 0.1% colchicine solution for 24 or 48 h. Oinuma (1952) obtained tetraploids by soaking dry soybean seeds in 0.1% colchicine solution for 24, 48 and 72 h. His results showed that the survival of resulting plants was poor.