Assessment of Genetic Divergence in Sorghum [Sorghum bicolor (L.) Moench] using Mahalanobis D² Statistics

Abstract

Genetic divergence among genotypes can be measured using Mahalanobis D² statistics, which are widely used to classify genotypes into clusters based on multivariate traits. The present investigation was carried out during the kharif season of 2023 at the Instructional Research Farm, Rajasthan College of Agriculture, Maharana Pratap University of Agriculture and Technology, Udaipur, Rajasthan, to assess genetic divergence in sorghum [Sorghum bicolor (L.) Moench]. The experimental material comprised 60 sorghum genotypes and three standard checks, which were evaluated in an augmented design. Fourteen quantitative traits, including days to 50 per cent flowering, days to maturity, plant height, yield components, protein content and grain yield per plant, were recorded. Genetic divergence was estimated using Mahalanobis D² statistics, and genotypes were grouped using Tocher’s method. The 63 entries were classified into fourteen clusters, indicating considerable genetic variability among the material studied. Clusters III and IV each contained the highest number of genotypes, while clusters VIII to XIV were monogenotypic, suggesting the presence of distinct genotypes. Inter-cluster distances were generally higher than intra-cluster distances, indicating substantial divergence among clusters. The highest inter-cluster distance was observed between clusters II and IX, followed by clusters IX and XIV, suggesting that genotypes from these clusters may be useful in hybridisation programmes. Cluster mean analysis showed that clusters XIV, V and X had higher grain yield per plant, while cluster VII recorded the highest biological yield per plant. Grain yield per plant contributed the highest proportion to total divergence, followed by plant height, harvest index and biological yield per plant. The results suggest that selecting genetically diverse genotypes with desirable mean performance may help identify promising parents for hybridisation and selection in sorghum breeding.