Genetic diversity of traditional and improved rice (Oryza sativa L.) genotypes assessed using agro-morphological and physiological traits

Abstract

Rice (Oryza sativa L.) is a major staple crop possesses extensive genetic variability, particularly among traditional landraces that serve as valuable resources for yield improvement, stress tolerance and nutritional enhancement. The present study evaluated 130 rice genotypes for 21 agro-morphological traits and physiological traits under field conditions using an augmented design during kharif 2024. Genetic divergence was estimated using Mahalanobis D² statistics and genotypes were grouped using Tocher’s clustering method. The analysis classified genotypes into 33 clusters, with Cluster 1 comprising the highest number of entries (22), while Clusters 12–33 were represented by highly divergent singleton genotypes. Large clusters were characterised by early flowering, moderate maturity and optimal plant height, whereas medium and singleton clusters exhibited distinct trait combinations such as higher grain yield, longer flag leaf, increased tiller number, elevated chlorophyll content (SPAD) and greater 1000-seed weight. The presence of substantial inter-cluster divergence suggests wide genetic variability among the studied genotypes. Selection of genetically distant parents, particularly from singleton and medium clusters, may enhance heterosis and recombination for yield and adaptive traits. These findings provide insights into the genetic diversity of rice germplasm and support strategic parent selection for developing high-yielding, climate-resilient and nutritionally improved rice varieties.