Induced micro-mutations in rice - the frequency and spectrum of gamma ray induced height variations in rice variety-Jaya

Seeds of rice variety, Jaya, treated with moderate doses of (10, 20 and 30 kR) gamma rays were subjected to study the relative magnitude of induced variability and the type of mutations induced for height of plant in M2 and M3 generations. Progenies of 3352 M1 spikes, totalling to 35691 M2 plants and their subsequent progenies in M3 were analysed. To get wider variability, very large populations in all the generations were studied. The mean value, genetic variance and phenotypic frequency distribution with and between generations were studied. The treated population showed no significant shift in mean values from that of control. The variance was greater in the irradiated material compared to control. The variability was found to shift in both plus and minus direction from that of control with a higher frequency in the minus direction in M2. A high frequency of dwarf mutants was observed in 20 kR treated population in the M2 generation. The segregation ratio was higher in M2 compared to M3 generation. (author)