Integrative effects of nano and conventional fertilizers on performance and economics of onion (Allium cepa L.)

Onion productivity is often remains below the attainable levels inspite of its wide adaptability and high yield potential, largely due to inefficient nutrient management practices. Onion has a shallow and sparsely distributed root system, which limits its ability to absorb nutrients efficiently from the soil applied fertilizers, making it highly responsive to foliar application of nutrients. But only foliar application of nutrients will not able to meet the nutrients requirement of the crop. The integration of nano-fertilizers with conventional fertilizers offer a potential strategy to reduce conventional fertilizer inputs without compromising crop yield and quality. With this hypothesis, a field experiment was conducted during Rabi season of 2024-25 to evaluate the integrative effects of nano and conventional fertilizers on growth, yield, quality and economics of onion (Allium cepa L.) at Bengaluru conditions. Integrated application of 100% RDF with three foliar sprays of nano-fertilizers had recorded the highest plant height at 90 DAT (55.99 cm), maximum dry matter accumulation in onion bulb (11.27 g bulb⁻¹) and superior yield attributes, resulting in the highest bulb yield of 32.43 t ha⁻¹. This treatment also produced bigger bulbs with higher equatorial diameter (6.54 cm), more number of rings (12.1) and maximum average bulb weight (83.75 g). Besides, quality traits were markedly improved, with the highest total soluble solids (13.95 °Brix) under integrated nutrition. However, maximum ascorbic acid (76.00 mg 100g⁻¹) and antioxidant activity (229.70 mg 100g⁻¹) were observed in onion bulbs grown under only foliar application of nano-fertilizers and 100% RDF, respectively. Economically, integrated nutrient management recorded higher gross and net returns, whereas foliar application of nano-fertilizers alone had achieved the highest benefit-cost ratio due to lower input costs. The study demonstrates that combining foliar application of nano-fertilizers with soil application of conventional fertilizers is an efficient and economically viable strategy for enhancing growth, yield and quality of onion under Eastern Dry Zone conditions of Karnataka.