Polyethylene glycol mediated early stage screening of drought responsive traits for rainfed condition in rice (Oryza sativa L.) germplasm

Rice (Oryza sativa L.) is an important staple crop and drought stress is a major constraint on its productivity. Early-stage seedling screening offers a rapid means of identifying drought related traits before field evaluation. This study aimed to evaluate genetic variability and identify key physiological and growth-related traits associated with drought tolerance among 25 rice genotypes using a two factor completely randomised design (CRD), comparing normal (control) conditions with polyethylene glycol (PEG-6000) induced drought stress (10 and 15 % PEG, pooled as a single stress treatment for analysis). Analysis of variance (ANOVA) revealed significant differences among genotypes, treatments and their interactions for most traits, indicating considerable genetic variability. Stress markedly reduced growth and water status traits, including germination percentage (GP), seedling vigour index (SVI) and relative water content (RWC), while proline content increased substantially, reflecting its role in osmotic adjustment. Traits with the highest coefficients of variation under stress, namely proline, SVI and RWC, indicated the greatest potential for genotype selection. Principal component analysis showed a shift from growth dominated variation under normal conditions (principal component 1 (PC1), 50.27 %) to a survival dominated pattern under stress (PC1, 61.67 %), driven primarily by proline, RWC and root length (RL). Based on this integrated analysis, genotypes such as Sahbhagi, CSR-23 and NDR-2064 exhibited superior performance by maintaining higher seedling vigour, water status and osmotic balance under stress conditions, indicating their potential as donor parents for drought tolerance breeding.