multivariate analysis of agronomic and physiological traits in a wheat recombinant inbred lines (rils) under drought stress

Drought stress is a primary constraint on global wheat production, necessitating the development of resilient cultivars. this study investigated the genetic basis of drought tolerance by evaluating a population of 169 wheat recombinant inbred lines (rils) across two growing seasons under well-watered and drought-stressed conditions. we assessed seven key agronomic and physiological traits: relative water content (rwc), chlorophyll content (spad), plant height (ph), thousand grain weight (tgw), biological yield (by), grain yield (gy), and harvest index (hi). combined analysis of variance (anova) revealed highly significant effects of genotype, year, and irrigation treatment on all traits. drought stress consistently and significantly reduced all measured traits, with mean gy declining by approximately 25–30%. correlation and principal component analyses (pca) demonstrated structured relationships among traits under drought. although by remained a key determinant of yield, rwc was identified as a reliable positive indicator of sustained gy and by under drought stress. in contrast, spad emerged as a prominent factor in the selection of drought-tolerant genotypes. cluster analysis identified distinct subpopulations, highlighting rils such as ril_101 and ril_41 that exhibited constitutive traits for high yield potential and robust water maintenance across environments (defined by the combination of irrigation treatment and year). our findings demonstrated that drought resilience is governed by the maintenance of water status coupled with yield stability, rather than by vegetative greenness alone. the identified elite rils provide valuable germplasm for breeding programs and for mapping quantitative trait loci (qtls) associated with drought tolerance, thereby offering a pathway to the development of high-yielding, drought-resilient wheat varieties.