Selection parameters and genetic diversity studies in Indian mustard (Brassica juncea L. Czern & Coss)

Abstract

The present investigation was carried out at Crop Research Centre of Sardar Vallabhbhai Patel University of Agriculture and Technology, Meerut, U.P with 40 diverse genotypes of Indian mustard. Observations were recorded on various characters viz; days to 50% flowering, days to maturity, plant height, number of primary branches per plant, number of secondary branches per plant, numbers of siliquae on main axis, length of main axis, siliqua length, number of seeds per siliqua, 1000 seeds weight, biological yield per plan, harvest index, oil content, grain yield per plant. Analysis of variance revealed substantial amount of variability for all fourteen characters. It indicates the wide spectrum of variability among the genotypes. The phenotypic and genotypic coefficient of variation was found to be high for grain yield per plant. Moderate (10-20%) GCV and PCV was recorded for number of primary branches/ plant, number of secondary branches/ plant, number of siliquae on main axis, length of main axis, siliqua length, number of seeds per siliqua, 1000 seeds weight, biological yield per plant. Further, the phenotypic coefficient of variance was higher in magnitude than the respective genotypic coefficient of variance for all the characters. It is interesting to note that the differences between GCV and PCV values were minimum implying least influence of environment. Heritability values for the characters viz.,days to 50% flowering, number of secondary branches per plant, number of siliquae on main axis, length of main axis, siliqua length, number of seeds per siliqua, 1000 seeds weight, biological yield per plant and grain yield per plant was found to be high. Most of the characters viz., grain yield/ plant, biological yield/ plant, number of secondary branches/ plant, 1000 seeds weight, length of main axis, number of siliquae on main axis and siliqua length had shown high heritability and genetic advance as per cent mean. However, the direct selection of genotypes can be done through these characters for further improvement of genotypes. Grain yield per plant exhibited significant association in positive direction with biological yield/ plant, number of secondary branches/ plant, number of siliquae on main axis, number of primary branches/ plant, siliqua length, length of main axis and harvest index at both genotypic and phenotypic level. This could be because of linkage of genes determining these characters. Among the various traits studied biological yield per plant and harvest index had high positive direct effect followed by number of seeds per siliqua, length of main axis and siliqua length at both genotypic and phenotypic levels on grain yield per plant along with highly significant correlation in the desirable direction towards grain yield per plant. Biological yield/ plant and harvest index exposed the indirect positive effect via number of seeds/ siliqua, length of main axis, number of primary branches/ plant, number of secondary branches/ plant, number of siliquae on main axis, siliqua length and 1000 seeds weight at both genotypic and phenotypic levels on grain yield per plant. Based on D2 values 40 genotypes were grouped into 5 clusters, maximum genotypes eleven obtained in cluster IV after that cluster I with nine genotypes, cluster V with eight genotypes, cluster III with seven genotypes and cluster II with five genotypes. The maximum intra cluster was in cluster IV. The maximum inter cluster distance was revealed between cluster II and V. It is clearly indicated that the genotypes included in this cluster are having wide spectrum of genetic diversity.