Efficient nitrogen (N) management is vital for sustainable rice production, given the heavy reliance on urea and substantial environmental losses associated with its use. This study evaluated the integrated use of nano urea plus [n-UP; 20 % N (w/v)] and nano DAP [n-DAP; 8 % N (w/v) and 16 % P (w/v)] to improve growth, physiology, biochemical, yield and nitrogen use efficiency (NUE) of rice under a reduced recommended dose of nitrogen (RDN). A field experiment was conducted during rabi 2023 using the rice variety ADT 53 in a randomised block design (RBD) with 8 treatments and 3 replications. The results revealed that 75 % RDN along with foliar applications of n-UP at the active tillering (AT) stage and n-DAP at the panicle initiation (PI) stage significantly enhanced physiological traits such as photosynthetic rate (35.5 µmol CO₂ m-2 s-1), stomatal conductance (0.568 mol H₂O m-2 s-1), Fv/Fm ratio (0.836) and biochemical traits such as soluble protein (SP) (24.1 mg g-1) and nitrate reductase (NR) activity (135.5 µg NO₂- g-1 h-1). This treatment also recorded the highest grain yield of 6.3 t ha-1, grain N (0.75 %), straw N (1.44 %) and improved NUE indices, including N uptake efficiency (41.0), AE (25.9), physiological efficiency (32.1) and NUE(yield-based) (17.7). Correlation and cluster analyses revealed strong positive associations between NUE indices and yield, demonstrating that 75 % RDN with nanofertilisers was equally effective as 100 % RDN. The study confirms that staggered foliar application of n-UP and n-DAP can achieve 25 % fertiliser savings while sustaining yield and enhancing NUE.
