Mutagenic effect of gamma rays on induced mutation and principal component analysis of yield characters on green gram in M₂ generation

The present study was aimed to evaluate the effect of gamma irradiation on green gram through chlorophyll mutation frequency, leaf mutation frequency, mutagenic effectiveness and efficiency and principal component analysis. Eight different types of chlorophyll mutants, namely albino, aurea, striata, tigrina, xantha, chlorina, viridis, xanthaviridis and variegated were observed at different doses of gamma irradiation in M-2 generation. Albino showed the highest frequency percentage (0.229) followed by Viridis (0.163) and Xantha (0.131) and the highest frequency was noted at 500 Gray (Gy). Though, chlorophyll mutants can be lethal in nature, they increase genetic variability and induce new traits. Leaf mutant is another key indicator for induced mutations that induce leaf morphology changes and the highest frequency was noted in 500 Gy. Among the mutagenic treatments, the mutagenic effectiveness shows the maximum at 100 Gy and efficiency shows at 500 Gy. This indicated that low to moderate doses are more effective for induced mutation. This was also confirmed by Principal Component Analysis (PCA) results, which specified that gamma irradiation of 500 Gy indicated that the first five principal components were attributed to 70.82% total variability of traits studied. From this, the experimental finding evidently showed that 500 Gy of gamma irradiation, an optimum dose, resulted in considerable variation in all the parameters analyzed.