Mahalanobis D² Analysis of Genetic Divergence in Soybean (Glycine max (L.) Merr.) for Selecting Suitable Parents in Hybridization

Abstract

Soybean (Glycine max (L.) Merr.) is an important grain legume and oilseed crop, and sustained genetic improvement depends on the availability and effective utilisation of diverse germplasm. Assessment of multivariate phenotypic divergence can assist in identifying complementary parents for hybridisation and broadening the genetic base of breeding populations. Thirty soybean genotypes were evaluated during Kharif 2018 at the Agricultural Research Station, Kasbe Digraj, Sangli, Maharashtra, in a randomised block design with three replications to quantify phenotypic genetic divergence and identify parents for hybridisation. Eleven agro-morphological and quality traits were subjected to Mahalanobis D² analysis and Tocher clustering. The genotypes were grouped into eleven clusters; Cluster I contained 12 genotypes and Cluster II contained nine, whereas Clusters III–XI were monogenotypic. Average inter-cluster D² values ranged from 4.32 (Clusters III–VI) to 13.06 (Clusters III–IX). Other highly divergent combinations included III–XI (12.98), VI–XI (11.84), VI–IX (11.81), V–IX (11.66) and II–X (11.39). Pods per plant contributed most to total divergence (31.26%), followed by seeds per pod (18.39%), plant height (15.86%), days to 50% flowering (10.11%) and seed yield per plant (9.20%). Cluster X recorded the highest mean seed yield per plant (14.81 g), Cluster III the highest 100-seed weight (18.32 g), Cluster VIII the highest SPAD value (48.83), and Cluster V the highest protein (41.27%) and oil content (19.97%). The results identify phenotypically contrasting parental combinations for soybean improvement. Validation across environments and where possible, with molecular or genomic diversity information is required before routine use in a breeding programme.