Variation in Quantitative Characters in the F₂ Population Derived from Unirradiated and Irradiated Hybrids of Rice*

The hybrid seeds from japonica × indica crosses of Oryza sativa were irradiated to induce and measure the variability for quantitatively inherited characters and recover types combining good quality of indica and resistance to bacterial blight available in japonica parents. The results suggessed that the irradiation of F_: seeds resulted in significant increase in the range of variation for most of the characters observed in the F₂ generation. However, the means either remained same or shifted to either direction. The recovery of segregants with good quality coupled with bacterial blight resistance, was more in the irradiated than in the non-irradiated F₁ population.