Nano nitrogen application enhances the physiological response of rice leaves under different soil types

Nano-nitrogen (nano-N) fertilizers have been developed to boost the efficiency and lessen the environmental footprint of conventional nitrogen (N) fertilizers in lowland rice cultivation.This study examined the impact of combining nano-N with existing N fertilization on rice leaf physiology.A greenhouse experiment tested five concentrations of nano-N (0 to 4 mL L -1 ) alongside a one-third reduction in the standard N rates across Aeric Epiaquents, Vertic Endoaquepts, and Typic Endoaquepts.Observations were made primarily on leaf dry weight, leaf area, chlorophyll content, photosynthesis rate, dissolved sugar levels, nitrate reductase activity (NRA), and glutamine synthase activity.The results showed that nano-N application increased chlorophyll a and b levels and enhanced NRA even with a 50% reduction in top-dressed nitrogen, equivalent to 46 kg of urea.In particular, the 2 mL L -1 nano-N treatment resulted in 34% higher starch and 28% more total non-structural carbohydrates than farmer-practice fertilization, driven by increased chlorophyll at panicle initiation and elevated NRA during grain filling.These findings suggest that nano-N fertilization can increase chlorophyll content, enzyme activity, and carbohydrate accumulation in rice leaves, providing a promising approach to improve nitrogen use efficiency, reduce environmental risks linked to overfertilization with N, and enhance yields through improved plant physiological processes.