author(s)
Yashaswini KP, SM Prasanna and Somashekhargouda Patil

abstract
Tomato (Solanum lycopersicum L.) is a nutrient-intensive crop that requires efficient nitrogen management to achieve optimal growth and fruit quality. Traditional urea-based fertilizer, though widely used, suffers from low nitrogen use efficiency (NUE), resulting in substantial nutrient losses and environmental concerns. This study evaluated the influence of nano urea, a novel nitrogenous fertilizer, applied in combination with conventional urea under varying nitrogen regimes, on the primary nutrient content (N, P, K) in tomato leaves and fruits. Twelve fertilizer treatments were assessed, including full (100%), moderate (75%) and low (50%) recommended dose of nitrogen (RDN), applied through conventional urea and nano urea, at different growth stages. Results revealed that treatment T₄ comprising 100% RDN with 50% applied as basal dose and nano urea foliar sprays at both 30 and 45 days after transplanting (DAT) consistently recorded the highest nutrient content in leaves and fruits (N: 3.33% and 0.36%, P: 0.19% and 0.34%, K: 1.73% and 2.09%, respectively). Treatments combining nano and conventional urea (T₂ and T₃) also significantly improved nutrient uptake, while reduced nitrogen treatments (50% RDN) showed comparatively lower nutrient accumulation, even when supplemented with nano urea. The findings highlight that nano urea enhances NUE, nutrient uptake and fruit nutritional quality, especially when applied in conjunction with conventional nitrogen sources under optimal nitrogen regimes. While nano urea showed promise in partially mitigating nutrient deficiencies under reduced RDN, it could not fully substitute for conventional nitrogen. Thus, nano urea serves as an efficient complementary input in sustainable nutrient management strategies. Future research should focus on its long-term effects on crop productivity, soil health and economic viability under field conditions.