Effect of Nano Nitrogen on Growth, Yield and Nutrient Uptake of Bt Cotton

Aims: Foliar application of nano nitrogen is aimed to reduce the soil application of conventional nitrogen. Nano fertilizers enhance crop growth, yield and quality while enhancing the faster nutrient uptake and reducing costs. They provide precise nutrient management, matching crop growth stage and offer increased surface area for metabolic reactions. This boosts photosynthesis, leading to higher dry matter production and crop yield. Foliar application of nano urea (liquid) at flowering, boll initiation and boll development stages in cotton fulfills the nitrogen requirement and reflects higher crop productivity and quality. Higher productivity of crops in sustainable manner could be achieved applying appropriate combination of conventional fertilizer and nano fertilizers.

Study Design: The experiment was laid out in split design with three replications.

Place and Duration of Study: A field experiment was conducted in shallow black soils at Main Agricultural Research Station, Raichur, during kharif 2022.

Methodology: There were fifteen treatment combinations, consisting of different doses of RDN (50 % N, 75 % N and 100 % N) with different concentrations of nano urea sprayed at 90, 100 DAS and 135 DAS for US-7067 BG-Ⅱ hybrid of Bt cotton.

Results: Application of 100% RDN has recorded significantly higher plant height, sympodial branches plant-1 and total dry matter accumulation (176.9 cm, 27.1 and 430.31g plant-1, respectively) followed by 75 % RDN (168 cm, 26.7 and 426.91 g plant-1, respectively) which found on par with each other. It also produced higher number of bolls plant-1 (50.3), boll weight (5.81 g) and seed cotton yield (3388 kg ha-1) followed by 75 % RDN (50.2, 5.36 g and 3376 kg ha-1, respectively) which found comparable with each other. Foliar application of nano urea @ 0.6 per cent each at 90, 100 and 135 DAS has recorded significantly higher plant height (180.8 cm), sympodial branches plant-1 (28.5), total dry matter accumulation (429.42 g plant-1), number of bolls plant-1 (52.2), boll weight (5.93 g) and seed cotton yield (3485 kg ha-1) followed by foliar spray of nano urea @ 0.4 per cent each at 90, 100 and 135 DAS (173.3 cm, 28, 428.52 g plant-1, 51.8, 5.67 g and 3465 kg ha-1, respectively) which found on par with each other. Similar trend was recorded with regard to nutrient uptake by cotton.

Conclusion: Foliar application of nano urea reduced the dosage of conventional nitrogen by 25 per cent. There was linear increase in seed cotton yield (kg ha-1) with increasing levels of nitrogen levels.