Evaluation of induced genetic variability in agronomic traits by gamma irradiation in canola (Brassica napus L.)

摘要

In the present study, the induced variability caused by gamma rays in agronomic traits comprising plant height, days to flowering, days to maturity, number of fruits/plant, number of seeds/fruit, 1000-seed weight and seed yield/plant was investigated. Seeds of two canola cultivars ('RGS003' and 'Sarigol') were treated with 0, 800, 1000, 1200 Gy of gamma rays and the resultant M2and M3lines were grown under field conditions. Heritability (h2), genotypic coefficient of variation (GCV), phenotypic coefficient of variation (PCV) and genetic advance of mean (GAM) were also estimated. The relationships between traits were also determined using correlation coefficient, path analysis and multiple stepwise regression analyses. Results of analysis of variance indicated highly significant effect of mutagenic doses, genotypes and genotype × dose interaction on the traits, indicating the differential response of genotypes to mutagenic treatments in terms of inducing genetic variations. The results revealed a higher variation in the treated populations than the control for all of the traits, with the highest GCV, PCV and GAM belonging to seed yield per plant. The highest variations induced with treatment of 1000 Gy of gamma rays in most of the traits in 'RGS003' cultivar, while 800 Gy gamma rays induced similar conditions in 'Sarigol' cultivar. The relationship between traits revealed major contribution of number of fruits per plant on justifying seed yield variation in both M2and M3generations. These results indicate that this yield component is the major determinants for fruit-yield differences among plants which also positively influences by irradiation mutagen (γ rays).