Frequency and spectrum of gamma ray induced variations in the weight of ears in rice variety jaya

Abstract

The relative magnitude of induced variability in the weight of ear was assessed after treating dry seeds of rice variety jaya with 10, 20 and 30 kR exposures of gamma rays. The treated population showed a significant reduction in mean value both in M, and M:: without any significant differences between the seven M, panicle categories. Studies on the phenotypic frequency distribution of the mutants in M, and M8 showed bidirectional shift compared to control. The analysis of variance showed significant variation both in M, and M9 for negative mutation frequency. Both in negative and positive mutation frequencies there were no significant differences among the seven M, panicle categories. As there is a reduction in segregation values in later generations it is better to have selection for desirable mutants in M, than in M.2. The higher values both in genetic advance and heritability observed in this study suggest that improvement through gamma ray irradiation is possible in this particular character.