Study on Morphological Variations among Winged Bean (Psophocarpus tetragonolobus L.) Genotypes under Foothill Conditions of Nagaland, India

Abstract

Winged bean (Psophocarpus tetragonolobus L.) is a highly nutritious but underutilised tropical legume with considerable potential for enhancing food and nutritional security. The present study was conducted to assess morphological diversity among 30winged bean genotypes and one check variety (KAU Nitya) under the foothill conditions of Nagaland during the Kharif seasons of 2022–23 and 2023–24. The experiment was laid out in a Randomised Complete Block Design (RCBD) with three replications. Morphological characterisation was carried out using IBPGR (1982) descriptors and RHS colour standards for vegetative, floral, and pod traits. Considerable phenotypic variation was observed among the evaluated genotypes. Abundant plant growth (74.19%), medium leaflet size (77.42%), deltoid leaflet shape (87.10%), and green stem colour (90.32%) were the predominant vegetative traits. Similarly, green calyx and blue corolla colours (90.32%), green pods without specks (93.55%), and green pod wings (93.55%) were the most frequent reproductive characters. Pod shape exhibited comparatively greater variability, with four distinct phenotypic classes identified. Cluster analysis based on qualitative traits grouped the 31 genotypes into four clusters, with the greatest inter-cluster distance observed between Clusters II and III (9.482), indicating substantial morphological divergence. Principal component analysis revealed that the first three principal components accounted for 84.88% of the total variation, with pigmentation-related traits contributing most strongly to genotype differentiation. Genotypes NUWB-19, NUWB-33, NUWB-11, NUWB-26, NUWB-35, and NUWB-32 exhibited distinct morphological characteristics and occupied divergent positions in both cluster and PCA analyses. These genotypes represent valuable germplasm resources for parental selection, conservation, and pre-breeding programmes aimed at broadening the genetic base of winged bean and developing improved cultivars adapted to diverse agro-ecological conditions.