Assessment of Genetic Variability Parameters in Indian Mustard (Brassica juncea L.)

Knowledge of genetic variation and how yield-related characteristics are inherited forms the foundation for crop improvement programs in Indian mustard (Brassica juncea L.). This study was conducted to examine variability parameters, heritability estimates, and expected genetic gains for seed yield and associated characteristics. The experimental material comprised ten parental genotypes and their forty-five F₁ hybrids evaluated across fifteen quantitative traits using a randomized block design with three replications. Analysis of variance demonstrated highly significant differences among genotypes for all characteristics under study, confirming the presence of considerable genetic diversity within the material. High phenotypic and genotypic coefficient of variation values (>20%) were recorded for biological yield per plant, seed yield per plant, harvest index, siliquae number per plant, and primary and secondary branch numbers. These findings point to substantial opportunities for improvement through phenotypic selection. Moderate GCV and PCV values characterized plant height, leaf area index, test weight, and flowering duration traits. The minimal differences observed between phenotypic and genotypic coefficients across most characteristics suggested limited environmental interference in their expression. Traits including siliquae number per plant, plant height, harvest index, seed yield per plant, biological yield per plant, and main raceme length exhibited high heritability combined with high genetic advance (as percentage of mean). This pattern indicates predominance of additive gene effects and supports the efficacy of direct selection methods. Oil content, while showing high heritability, demonstrated low genetic advance, suggesting non-additive gene effects may be involved. The results collectively indicate that selection focused on key yield determinants can substantially improve seed yield and productivity in Indian mustard breeding initiatives.