Evaluation of mutant lines of rice (Oryza sativa L.) for drought tolerance at seedling and reproductive stages

Abstract

Rice productivity severely decreases due to the drought stress at seedling and reproductive stage. This study evaluated drought tolerance in 20 rice mutant lines at seedling and reproductive stages, comparing them to tolerant (Nagina-22) and susceptible (IR-64) varieties. Experiments were conducted in tunnels and fields using an Augmented Randomized Complete Block Design during the Kharif season 2023. Seedlings were subjected to 15 days of drought stress by withholding irrigation, and 14 traits were recorded. In the field, reproductive-stage drought stress was imposed for 30 days by ceasing irrigation.  Analysis of variance revealed significant (p<0.05) and highly significant (p<0.01) differences among mutant lines for seedling traits under drought stress. Highly significant (p<0.01) differences were also observed for all traits during reproductive-stage drought stress. Seedling vigor is positively and strongly correlated with other traits. Seedling recovery was strongly and positively correlated with seedling height, leaf rolling, seedling dryness, and seedling vigor. Grain yield strongly and positively correlated with productive tillers per plant, panicle length, primary branches per panicle, number of spikelets per panicle, 1000 grain weight, harvesting index, filled spikelets per plant, chlorophyll content, photosynthesis rate and Stomata conductance rate. In quarter 1, quarter 2, quarter 3 and quarter 4 in the biplot, the traits which were closed to each other are correlated and same color of the mutant lines were similar on the bases of traits. Cluster Analysis on the basis of traits recorded after drought stress at seedling stage and reproductive stage divided the mutant lines into 3 clusters and 4 clusters, respectively. Results of the research indicated that mutant lines such as 54, 58-1, 129-1, 130-2, 582-1, 631, 931, 1227-1 and 1230-1 showed drought tolerance during drought stress at seedling and reproductive stage.