Studies on genetic divergence and isozyme variability in rice (Oryza sativa L.)

摘要

Fifty-four elite gei mplasm lines being maintained at Agricultural Research Station, Nellore were evaluated for their genetic diversity with regards to yield, yield components and quality trails. The genotypes were classified into nine clusters, basedon Mahalanobis D~2 statistic. Geographical and genetic diversity were observed to be unrelated, as genotypes from diverse geographical regions were placed in the same cluster, while genotypes from the same centre were grouped into different clusters. Results on inter-cluster distances revealed maximum diversity between genotypes of clusters IV and VIII, Intra-cluster distance was maximum for cluster V, indicating the existence of variability within the cluster. A perusal of the results on cluster meansrevealed greater yield, number of grains per panicle, panicle length, plant height and days to 50% flowering for cluster IV, indicating the desirability of genotypes from the cluster for improvement of grain yield and the above yield components. Further, plant height and days to 50% flowering, together accounted for 82.04% of the total genetic divergence, indicating their importance in the choice of parents for hybridization programmes. Studies on isozyme variability of the nine best performing genotypes, obtained from each of the nine clusters, classified on the basis of Mahalanobis D~2 statistic confirmed their genetic diversity. The genotypes were distinguished based on presence, absence or intensity of the seven peroxidase and five esterase bandsobtained in the gel electrophoretic studies.