Effect of gamma-radiation and sodium azide on quantitative characters in rice (Oryza sativa L.)

Seeds of rice cultivar IAC-1246 received single and combined treatments of 10 or 20 Krad gamma-rays and 0.5 mM sodium azide (SA). The experiments were carried out to assess the effect of treatments on the mean and variance in second generation plants of the following quantitative traits: number of days to flowering (NDF), culm length (CL) and tiller number (TN). Ln general, the mutagenic treatments increased variance, but did not change the mean for the characters NDF and CL in the M-2 generation. There was no increase in the mean or variance of TN. The combined treatments of gamma-rays and SA resulted in larger variance in CL than for the treatments with,gamma-rays alone, but not higher than obtained with SA alone. Combined treatments with gamma-rays and SA did not increase the variance of NDF and TN when compared with the corresponding single treatments.