Multivariate analysis of phenotypic traits and trait associations for identifying elite lentil (Lens culinaris Medik.) genotypes using STI and MFV indices for breeding in salt-affected soil

Aims This study aimed to identify superior lentil genotypes with tolerance to both salinity and alkalinity stress through field phenotyping and robust trait selection indices. Methods A total of 500 lentil genotypes (317 indigenous, 183 exotic) were evaluated under natural field conditions—control, salinity (ECe ~7 dS/m), and alkalinity (pH ~9.3)—at the ICAR-CSSRI, Karnal. Data on seven agro morphological traits were analyzed via ANOVA, correlation, regression, and PCA. Two indices—the stress tolerance index (STI) and membership function value (MFV)—were employed to identify salt-tolerant genotypes on the basis of yield and multivariate trait performance. Results Highly significant variation was observed among the genotypes across the treatments. Compared with salinity, alkalinity stress had a more pronounced effect on key traits such as seed yield and pod number. Regression and PCA highlighted pods per plant, test weight, and plant height as key yield determinants. STI was more effective under salinity, whereas both STI and MFV performed equally well under alkalinity. Six genotypes (IC267104, IC248956, IC268241, IC267658, IC267657, and IC268240) consistently ranked highly under both stress types across indices. This study provides a comprehensive field-based evaluation of the salinity and alkalinity tolerance of lentil germplasm via integrated selection indices. The identified genotypes offer valuable resources for breeding programs targeting salt-affected soils and can serve as parents for mapping populations aimed at dissecting the genetic basis of stress tolerance in lentils.