Efficacy of nitrogen and Azolla spp. on growth and yield of black rice (Oryza sativa L.)

An experimental field study was carried out in the Kharif season of 2023 at the Crop Research Farm, Department of Agronomy, SHUATS, Prayagraj (U.P.). The experimental replications were conducted using a Randomized Block Design, with three levels of Nitrogen (0, 60, 90kg N/ha) and Azolla spp. (2, 4, 6t/ha), and one Control (NPK 120:60:60 kg/ha). In all, there were a total of ten treatments, each reproduced three times. The tested field had sandy loam soil texture with a neutral soil pH of 7.6, low organic carbon content of 0.372%, nitrogen content of 278.4 kg/ha, phosphorous content of 29.5 kg/ha, and potassium level of 217.3 kg/ha. The experimental results showed that treatment T₉ obtained significantly higher plant height (107.77 cm), dry weight (66.05 g), crop growth rate (57.27 g/m2/day), relative growth rate (0.0279 g/g/day), highest number of tillers per hill (22.07), panicles per m2 (282), test weight (15.23 g), grain yield (3.67 t/ha), stover yield (6.7 t/ha), and harvest index (35.74%). Transplanted Black Rice of variety BPT-2841 exhibited significantly greater maximum gross return (1,80,551.40 INR/ha), net return (1,05,496.30 INR/ha), and B:C ratio (1.41) in treatment T9. The investigation concludes that Nitrogen, being easily transportable in soil and plants, is a constituent of amino acids, nucleic acids, chlorophyll, enzymes, and hormones. These factors are essential in plant physiology and are associated with increased tillering, biomass production, protein synthesis, grain filling, yield, and quality. The availability, absorption, and utilization of nitrogen have a significant impact on these processes. Therefore, in the present experiment, the nitrogen requirements are met by applying 90kg of nitrogen through urea combined with 6t/ha of Azolla spp. This approach revealed superior performance in terms of both crop yield and economic returns .