Exploring rice genotypes for nitrogen use efficiency under different nitrogen regimes

Rice (Oryza sativa L.), relies heavily on nitrogen for growth and development. This study examines the effects of nitrogen levels on various growth parameters in forty rice genotypes. The crop features viz., tiller numbers, leaf area index and total dry matter production showed significant result with 50% and 100% RDN. This suggests that nitrogen aids crop growth and biomass accumulation by converting absorbed nitrogen into photosynthates. Among the 40 rice genotypes, IRGC 6386-1 exhibited higher chlorophyll fluorescence measurements indicating superior photosynthetic efficiency, enhanced chlorophyll and soluble protein content under varied nitrogen levels. The genotypes IRGC 6386-1 (3.01%), WAS 20 (3.32%), IRGC 116967-1 (3.98%), WAS 207 (4.36%) and among the variety, IR 64 (6.3%) showed least reduction in grain yield under 50% RDN. The genotypes IRGC 6386-1, WAS 207 and IR 64 consistently exhibited superior performance in physiological traits. Notably, IRGC 6386-1 displayed higher photosynthetic NUE trailed by TSIPALA FOTSY 1883, NIONOKA and WAS 20 at reduced N level. In this study, the best performing rice genotypes (IRGC 6386-1, WAS 20, IRGC 116967-1 WAS 207) including popular variety (IR64) yielded higher under reduced nitrogen level. A positive correlation was recorded with physiological traits, grain yield and NUE.