Enhancing nutrient use efficiency and productivity of transplanted Basmati rice through legume-based green manuring and nano-ZnO foliar fertilization

Widespread soil Zn deficiency limits productivity in flooded rice ecosystems. This highlights the need for integrated nutrient management to improve rice productivity. However, limited literature is available on the integration of green manuring and advanced zinc fertilizers along with microbial inoculants to enhance productivity and nutrient dynamics in rice. To address this gap, a two-year field experiment was conducted during the Kharif seasons of 2023 and 2024 at ICAR–IARI, New Delhi, using a split-plot design to evaluate the integrated effects of legume-based summer green manuring and different zinc fertilization strategies on growth, yield, nutrient uptake and efficiencies in Basmati rice. The results demonstrated that across two years, Sesbania aculeata green manuring (GM 1 ) significantly enhanced plant height (12.94%), number of tillers (16.63%), dry matter accumulation (10.82%), panicle length (3.39%), grains panicle −1 (8.70%), and grain weight panicle −1 (11.04%) over summer fallow. Foliar application of 0.2% nano-ZnO (NZO FA) further improved these growth and yield attributes. Grain yield increased by 13–15% with GM 1 and by 14–15% with 0.2% NZO foliar application. Both treatments significantly increased nitrogen content and uptake in husk, bran, kernel, and straw. On average over the two years, GM 1 increased nitrogen uptake in the kernel by 29.75% and total uptake by 29.49% over summer fallow, while 0.2% NZO FA enhanced it by 79.75% and 59.41%, respectively, over zinc control. GM 1 improved the agronomic efficiency of nitrogen, whereas zinc-induced nitrogen recovery efficiency, zinc agronomic efficiency, and zinc recovery efficiency were higher under summer fallow. Among zinc treatments, 0.2% NZO FA recorded the highest values for agronomic efficiency of nitrogen and Zn-induced nitrogen recovery efficiency. However, we found higher Zn agronomic efficiency with reduced application of Zn under 0.1% NZO FA and Zn-EDTA, which recorded a 9-fold increase in Zn recovery efficiency in Basmati rice. Overall, integration of leguminous green manuring with advanced Zn fertilization strategies, particularly nano-ZnO and Zn-EDTA, demonstrated potential in enhancing nutrient uptake, improving nitrogen and zinc use efficiencies and Basmati rice productivity.