Evaluation of Genetic Diversity in Sorghum Genotypes for Drought Tolerance Using Mahalanobis’ D2 Analysis

Genetic diversity is vital in plant breeding and crop improvement, enabling the development of varieties resilient to biotic and abiotic stresses. Mahalanobis' D² analysis is a robust multivariate statistical method for assessing genetic diversity, offering precise measures of genetic divergence. This study aimed to evaluate the genetic diversity of twenty sorghum (Sorghum bicolor L. Moench) genotypes under rainfed and irrigated conditions using Mahalanobis’ D² statistics. The experiment was conducted at the Main Agricultural Research Station (MARS), Dharwad, involving twenty genotypes sourced from the AICRP sorghum, Dharwad, India. The genotypes were sown in medium black soil under two moisture levels: rainfed and irrigated. Morphological, physiological, phenological, and yield-related traits were recorded to identify drought-tolerant genotypes. Genetic divergence was estimated using D² statistics, and genotypes were grouped into clusters using Tocher’s method. Under rainfed conditions, the genotypes were classified into six clusters, while under irrigated conditions, they were grouped into three clusters. The intra-cluster distances ranged from 7.79 to 12.14 under rainfed conditions and from 8.14 to 15.74 under irrigated conditions. The inter-cluster distances revealed significant genetic variation, with the highest divergence observed between Clusters III and V under rainfed conditions and Clusters II and III under irrigated conditions. These findings highlight the presence of substantial genetic diversity among sorghum genotypes, facilitating the selection of diverse parental lines for breeding programs aimed at enhancing drought tolerance. The insights gained from this study contribute to the development of resilient sorghum varieties capable of withstanding water scarcity, ensuring sustainable agriculture, and promoting food security in drought-prone regions.