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: N0 (control), N60 (½ of recommended N), and N120 (recommended N) for two consecutive years (2020 and 2021) under a split plot design. In both growing seasons, the application of N120 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, N60 and N120 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 N0. Furthermore, the application of N60 and N120 improved GY and HI by 47.6% and 59.4%, and 3.4% and 6.2%, respectively, over N0. Nitrogen addition (N60 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 N0. 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.