Deciphering Salinity Tolerance in Mungbean (Vigna radiata L.) through Root System Architecture, Multivariate Divergence Analysis and Multi-trait Ideotype Selection

Background: Soil salinity is a major abiotic constraint on mung bean (Vigna radiata L.) productivity. Breeding resilient varieties requires an understanding of genetic diversity and the identification of salt-tolerant genotypes, with root system architecture being a key determinant of adaptation to saline conditions. Methods: The experiment was conducted at Lovely Professional University, Punjab, using a factorial randomized block design (FRBD) with three replications. Root architecture was examined via scanning, while genetic divergence was assessed using Mahalanobis D2 cluster analysis and principal component analysis. Genotype screening employed nine stress tolerance indices along with the multi-trait genotype Ideotype distance index (MGIDI). Result: Root structure progressively deteriorated with increasing salinity, with KDMB-5023 and KDMB-5025 showing relatively greater structural resilience. Mahalanobis D2 analysis grouped genotypes into four clusters, with the maximum inter-cluster distance observed between Cluster I and Cluster IV (D2 = 8.498). Principal component analysis retained three components explaining 92.40% of total variation, with plant height, shoot length, vigour index and leaf area collectively contributing 82.47% of genetic divergence. Multi-index stress tolerance analysis identified KDMB-5020, KDMB-5030, KDMB-5014, KDMB-5025 and KDMB-5001 as the most tolerant genotypes, while MGIDI ranked KDMB-5001 (3.210), KDMB-5018 (3.459) and KDMB-5011 (3.500) as genotypes closest to the ideal type, indicating substantial potential gains through selection.