Quality Improvement in Tomato through Integrated Application of Nano and Conventional Fertilizers in Mid-Hill Conditions of Himachal Pradesh, India

Background: The overuse of conventional fertilizers in tomato cultivation has led to reduced nutrient use efficiency and environmental concerns. Integrating nano-fertilizers with conventional sources offers a sustainable approach to enhance fruit quality and nutrient efficiency under field conditions. Methodology: The present study was conducted to evaluate the impact of integrated application of conventional and nano-fertilizers on the quality parameters of tomato (under field conditions in the mid-hill zone of Himachal Pradesh. The experiment was laid out during the summer season of 2023 in a Randomized Block Design (RBD) with 11 treatment combinations involving different levels of recommended dose of fertilizers (RDF) along with foliar-applied nano-NPK at 0.25%, 0.5%, and 1.0% concentrations. The standard RDF was applied through conventional sources, while nano-NPK was applied at 30 and 60 days after transplanting. Results: The results revealed significant improvements in fruit quality attributes under integrated nutrient treatments compared to the absolute control and sole RDF. Among all treatments, T7 (80% RDF + 1.0% nano-NPK) recorded the highest total soluble solids (4.56 °B), reducing sugar (2.69%), total sugar (3.55%), antioxidant activity (41.58%), and total chlorophyll content (1.80 mg g⁻¹). The highest ascorbic acid content (83.50 mg 100⁻¹ g) was observed under T4 (80% RDF + 0.5% nano-NPK), indicating improved physiological and biochemical traits. The absolute control (T11) consistently recorded the lowest values across all parameters. Conclusion: The enhanced performance of integrated treatments may be attributed to improved nutrient use efficiency, greater metabolic activity, and enhanced biosynthesis of primary and secondary metabolites promoted by nano-fertilizer application. The study demonstrates that the conjoint use of nano and conventional fertilizers, particularly at 80% RDF + 1.0% nano-NPK, is an effective and sustainable strategy for improving tomato fruit quality while reducing chemical fertilizer input.