Genetic Diversity in Indian Mustard [Brassica juncea L. Czern & Coss.] Genotypes for Yield & Its Attributing Traits under Terai Agro-climatic Zone of West Bengal, India

A comprehensive investigation was undertaken to evaluate the genetic variability among seventy-one genotypes of Indian Mustard (Brassica juncea L.) during the rabi season (winter season) of 2019-2020, employing a randomized complete block design with three replications. The primary objective of crop improvement programmes is to identify and use diverse lines, as genetic diversity is essential for agricultural phenomena such as heterosis and transgressive segregation. The analysis encompassed seven agronomic traits: plant height (cm), number of siliquae on the main shoot, siliquae on branches, seeds per siliqua, 1000-seed weight (g), oil content (%), and seed yield per plant (g). Genetic divergence was quantified using Mahalanobis D² statistics, classifying the genotypes into six distinct clusters. Cluster III, comprising 32 genotypes, was the largest, followed by Cluster I (17 genotypes), Cluster VI (10 genotypes), Cluster V (8 genotypes), and Clusters II and IV, each containing two genotypes. The greatest mean intracluster divergence was observed in Cluster VI, whereas Cluster II displayed the least. The maximum intercluster distance between Clusters I and VI, while the minimum was noted between Clusters II and IV. Among the traits assessed, seed yield per plant emerged as the most substantial contributor to genetic divergence, followed sequentially by siliquae on branches, oil content, 1000-seed weight, seeds per siliqua, siliquae on the main shoot, and plant height.