RECONFIGURING RICE PRODUCTION UNDER COMPOUND CLIMATE EXTREMES: GENOTYPIC VARIATION IN YIELD STABILITY, RESOURCE-USE EFFICIENCY, AND ADAPTIVE RESPONSES UNDER HUMID SUBTROPICAL CONDITIONS

Abstract

Rice genotypes often respond differently when heat and water-related stresses occur together, and these differences can lead to considerable variation in yield stability between seasons. This study evaluated genotypic variation and yield stability of twelve rice genotypes under contrasting reference, heat–moisture-deficit and excess-moisture environments during the 2022 and 2023 kharif seasons at KVK Dhalai, Tripura, India. The genotypes were evaluated in a randomized complete block design with four replications across six year × environment combinations. Environment strongly influenced grain yield: pooled mean yield was approximately 5.60 t ha−1 under reference conditions, 4.05 t ha−1 under heat–moisture deficit and 4.92 t ha−1 under excess moisture. Across environments, mean yield ranged from 4.46 t ha−1 in Swarna to 5.26 t ha−1 in CR Dhan 802. CR Dhan 802 (5.26 t ha−1), CR Dhan 801 (5.19 t ha−1), Gomati Dhan (5.12 t ha−1) and Tripura Chikan Dhan (5.09 t ha−1) recorded comparatively high mean yields. Sahbhagi Dhan showed the lowest yield variability (CV 8.8%) and retained 84% of its reference yield under heat–moisture deficit, whereas Swarna-Sub1 and Ranjit-Sub1 retained 96% and 92% of reference yield, respectively, under excess moisture. Grain yield showed GCV and PCV values of 6.8 and 8.8%, respectively, with an entry-mean broad-sense heritability of 70.9%. Combined analysis indicated significant effects of genotype and genotype × environment interaction on grain yield. Overall, the genotypes differed appreciably in productivity, response to stress and yield stability, highlighting the value of evaluation across contrasting environments when selecting rice material for variable climatic conditions.