Insights Into the Salt Tolerance of Lentil (Lens culinaris Medik): Characterisation of Germplasm Resource to Accelerate Crop Improvement

Abstract

Evaluating diversity panels for their ability to endure salt stress conditions is essential for the development of breeding lines. A set of 100 lentil genotypes was characterised for their salt tolerance during 2021–22 and 2022–23. Salt stress lead to an average reduction of 43.96% in plant height, 19.46% in primary branches per plant, 44.45% in pods per plant, 47.26% in seed weight, 36.39% in photosynthetic rate (Pn), 34.03% in transpiration rate, 33.95% in stomatal conductance (gsw), 27.75% in chlorophyll content, 30.04% in relative water content and 18.99% in membrane stability index (MSI). The K⁺ content decreased while the Na⁺ content increased in plant tissues of all genotypes with higher salt levels. Notably, genotypes IC241532, IC241529, LL1813, EC223237B, KM4, IC78387, LL1804, KM1, LL1823, LL1641, IC78387 and EC223212A demonstrated superior performance due to an enhanced antioxidant system. It was evidenced by increased proline content, alongside increased activity of superoxide dismutase, catalase, glutathione reductase, aspartate peroxidase activity and higher total soluble sugar content. Interestingly, a positive correlation was observed between yield per plant (YPP) and seed K⁺, shoot K⁺, Pn, gsw, shoot fresh weight (SFW) and root fresh weight (RFW) highlighting the importance of these key traits in enhancing plant tolerance to salt stress. Principal component analysis of 26 indices indicated a considerable level of genotypic variability among genotypes as well as a significant correlation between YPP and SFW, RFW under control and Pn, MSI, gsw, SFW, root dry weight (RDW) and 100-seed weight under salt stress. This study provides valuable insights into diverse lentil genotypes' agro-physiological and antioxidant responses to salt stress.