Field-Based Evaluation of Rice Genotypes for Enhanced Growth, Yield Attributes, Yield and Grain Yield Efficiency Index in Irrigated Lowlands of the Indo-Gangetic Plains

Nitrogen (N) fertilizers are widely used worldwide to increase agricultural productivity. However, significant N losses contributing to air and water pollution ultimately reduce the nitrogen use efficiency (NUE) of crops. Numerous research studies have emphasized the use of a low dose of N fertilizer, but few have focused on screening N-efficient rice genotypes. This study aimed to identify and screen ten rice genotypes that are N-use-efficient under different N fertilization treatments using the surface placement of neem-oil-coated urea: N-0 (control), N-60 (1/2 of recommended N), and N-120 (recommended N) for two consecutive years (2020 and 2021) under a split plot design. In both growing seasons, the application of N-120 yielded the highest panicles m(-2) (PAN = 453), filled grains panicle(-1) (FGP = 133), leaf area index (LAI = 5.47), tillers m(-2) (TILL = 541), grain yield t ha(-1) (GY = 5.5) and harvest index (HI = 45.4%) by the genotype 'Nidhi', being closely followed by the genotype 'Daya'. Four genotypes ('Nidhi', 'Daya', `PB 1728' and `Nagina 22'), out of the ten genotypes evaluated, responded well to different fertilization treatments with N with respect to the grain yield efficiency index (GYEI >= 1). Regarding N fertilization, N-60 and N-120 recorded the highest increase in PAN (28.5%; 41.4%), FGP (29.5%; 39.3%), test weight (29.5%; 45.3%), LAI at 30 days after transplanting (DAT) (143.7%; 223.3%), and LAI at 60 DAT (61.6%; 70.1%) when compared with N-0. Furthermore, the application of N-60 and N-120 improved GY and HI by 47.6% and 59.4%, and 3.4% and 6.2%, respectively, over N-0. Nitrogen addition (N-60 and N120) also significantly increased the chlorophyll content at 60 DAT (8.8%; 16.3%), TILL at 60 DAT (22.9%; 46.2%), TILL at harvest (28%; 41.4%), respectively, over N-0. Overall, our research findings clearly indicate that 'Nidhi' and 'Daya' could be efficient candidates for improved nitrogen use, grain yield and GYEI in the Indo-Gangetic plains of India.