Response of Rice (Oryza sativa L.) to Different Levels of Nano Fertilizers and Conventional Fertilizers on Growth and Yield

Abstract

Background: Nano fertilizers offer improved uptake, prolonged availability, and reduced losses. Conventional fertilizers exhibit low nutrient use efficiency due to losses via leaching, volatilization and fixation, leading to reduced yields, higher costs and environmental concerns. Aims: The study aims to evaluate the response of rice (Oryza sativa L.) to different levels of conventional fertilizers integrated with foliar applications of nano fertilizers (Nano Urea and Nano DAP) on growth parameters, yield attributes and overall productivity under rainfed conditions. Methodology: A field experiment was conducted during kharif 2024 at the Agricultural Research Station, Mugad, Dharwad, Karnataka, India. The experiment was laid out in a split-plot design with three replications. The main plot treatments consisted of three nutrient levels: N₁ – 50% RDN + 50% RDP + 100% RDK, N₂ – 75% RDN + 75% RDP + 100% RDK and N₃ – 100% RDN + 100% RDP + 100% RDK. Thus, a total of 19 treatment combinations were evaluated, including a control plot without foliar spray. Foliar applications of nano-fertilizers were carried out at the tillering and panicle initiation stages, while conventional fertilizers were applied as per the treatments. The recommended package of practices (RPP) for rice under rainfed conditions, comprising RDF: 100 kg N, 50 kg P₂O₅ and 50 kg K₂O ha-1 along with common FYM at 8.5 t ha-1, Azospirillum @ 2 kg ac-1 and PSB @ 2 kg ac-1, was applied uniformly to all plots.  Growth and yield observations included plant height, tillers per meter row length, leaf area index, SPAD chlorophyll content, dry matter production, panicle length, grains per panicle, test weight, grain and straw yields. The collected data were statistically analysed using the split-plot design procedure. Results: Among the treatments, the combination of 100% recommended nutrients with foliar Nano Urea + Nano DAP at 6 + 6 ml L⁻¹ (N₃F₆) recorded the highest values for key growth parameters: plant height (110.0 cm), number of tillers (86.00 m⁻¹ row length), leaf area index (5.21 at 90 DAS), SPAD chlorophyll values (44.00–45.35) and dry matter production (37.37 g plant⁻¹). This treatment also produced the maximum grain yield (55.63 q ha⁻¹) and straw yield (63.41 q ha⁻¹), representing a significant 29.37% increase in grain yield over the recommended package of practices (43.00 q ha⁻¹). Both main effects (nutrient levels and foliar nano treatments) and their interaction showed statistically significant differences for most parameters (based on CD values at 5% level of significance). Conclusion: Integration of nano fertilizers, particularly the combined foliar application of Nano Urea and Nano DAP at higher concentration, with the full recommended dose of conventional fertilizers significantly enhances nutrient use efficiency, vegetative growth, photosynthetic activity and ultimately grain and straw yields in rainfed rice. This approach offers a promising, sustainable strategy to improve productivity and reduce reliance on excessive conventional fertiliser inputs under rainfed ecosystems.