Genetic divergence analysis of field pea (Pisum sativum L.) genotypes across multiple environments for yield and associated traits

Abstract

The present investigation assessed genetic divergence among 70 field pea (Pisum sativum L.) genotypes across four distinct environments, employing pooled Mahalanobis D² statistics and Tocher’s procedure for multivariate cluster analysis. Environment-wise clustering patterns consistently delineated a single predominant cluster encompassing 26-39 genotypes, alongside multiple monogenotypic clusters, thereby indicating the concurrent presence of genetically related germplasm and highly divergent genotypes within the experimental material. Pooled analysis partitioned the genotypes into 14 discrete clusters, with Cluster I (42 genotypes) and Cluster II (10 genotypes) showing numerical predominance. Substantial inter-cluster distances were observed in pooled analysis between Clusters XI and XIII (22.65), substantiating extensive genetic divergence and indicating considerable potential for exploiting heterosis through strategic hybridisation programs. Cluster means revealed environment-specific as well as pooled superiority for economically important traits: under pooled analysis, Cluster VI exhibited maximum seed yield per plant (55.70 g), Cluster VII demonstrated superior biological yield per plant (63.14 g) and harvest index (28.21%), whereas Cluster XIII excelled in seeds per pod (9.43) and hundred-seed weight (26.42 g). Contribution analysis of morpho-physiological attributes toward total genetic divergence identified number of nodes per plant (12.46%), plant height (11.84%), and number of pods per plant (11.43%) as principal contributors in pooled analysis, with congruent patterns manifested across individual environments. The findings underscore the utility of divergent, trait-superior clusters as potential donor parents in breeding programs aimed at developing high-yielding, early-maturing, and resource-use-efficient ideotypes in field pea.