Genotypic variations in diverse accessions of linseed (Linum usitatissimum L.) germplasm under PEG-induced water stress and its implications for drought tolerance

Abstract

Water constraint is a crucial factor in determining the productivity and production of linseed or flaxseed globally. The root system of flaxseed consists of a single taproot mainly confined to the topsoil; thus, the structure of the root system significantly impacts the uptake of water from the soil. This research conducted root–shoot phenotyping on a diverse range of linseed germplasm under PEG-induced water deficit stress conditions to unravel the potential of genebank germplasm for drought tolerance. Varied responses to stress and substantial diversity in genotypic response were observed among the linseed accessions for all growth parameters under both normal and stress conditions. The application of PEG led to a decrease (ranging from 7.39% to 62.02%) in all parameters except chlorophyll content, which exhibited an increase of 13.76% in response to stress conditions. Principal component analysis revealed that the first four principal components (PCs) with Eigenvalue >1 explained 74.23% of the total variance, with the first PC alone accounting for 42.15% of the total variance contributed by various traits such as leaf width, shoot length, root–shoot biomass, root length, surface area, and volume. Assessing the comparative performance based on the stress susceptibility index (SSI) for shoot–root length and root surface area, a subset of 12 drought tolerant (SSI ≤ 0.50) and 5 susceptible (SSI > 1.00), genotypes was constituted for validation at the adult plant stage. The accessions IC0096648, IC0523799, IC0249015, IC0096587, IC0385336, IC0498744, IC0499170, EC0041481, IC0526017, IC0623723, IC0113110, and IC0621685 exhibiting tolerance to PEG-induced water stress during the initial (seedling stage) growth maintained physiological efficiency and yield at the adult plant stage. The elite drought-tolerant genotypes identified in the present study will provide access to genetically diverse material in breeding to enhance drought tolerance in linseed.