Seeds of rice (Oryza sativa L. cv.lTA 150) were exposed to varying concentrations of 0.063–1.00 per,cent of hydroxylamine, streptomycin and urea for 24 hours at 28°C. Treatment effects on germination, survival, maturity time, number of leaves/plant, dry weight, yield/plant and 100 seed weight as well as polled viability and chlorophyll content have been evaluated. Streptomycin was a more efficient mutagen than hydroxylamine and urea in inducing chlorophyll deficiencies and male sterility. All the three chemicals, induced increased spectrun) of variability in the characters under study. The viable materials possessing variability may, therefore, be used for the genetic improvement of rice. The effectiveness of the three chemicals on rice is ranked as Streptomycin > Hydroxylamine > Urea. The genetic factors from a sporophytic male sterile plant isolated from streptomycin treatment are currently being transferred to other rice varieties to enhance production ol hybrid seeds.
