Influence of conventional and nano fertilizers on growth, yield, quality traits, and economics of Bt cotton

Cotton (Gossypium hirsutum L.) is one of the most important fibre crops, contributing significantly to the textile industry and rural economy of India. Enhancing its productivity requires balanced and efficient nutrient management, and the use of nano-fertilizers has recently emerged as a promising alternative to conventional fertilization. A field experiment was conducted during Kharif 2023 at AICRP on Cotton, Chamarajanagar, to study the effect of conventional and nano fertilizers on a Bt-cotton hybrid. The experiment was laid out in a split plot design with three replications, comprising three levels of conventional fertilizers in the main plot (50 %, 75 % and 100 % RDNP) and four dosages of nano fertilizers in the subplot (nano urea @ 2- and 4-mL L⁻¹, nano DAP @ 2- and 4-mL L⁻¹), sprayed at 40, 60 and 80 DAS. The results revealed that among the conventional fertilizer levels, application of 100 % RDNP recorded significantly higher growth attributes, including plant height (172.7 cm), number of sympodial branches (31.8 plant⁻¹), and total dry matter production (326.32 g plant⁻¹). Yield attributes such as total number of bolls (47.3 plant⁻¹), good opened bolls (42.2 plant⁻¹), and seed cotton yield (1453 kg ha⁻¹) were also superior in this treatment, along with maximum gross returns (₹1,23,491 ha⁻¹) and net returns (₹47,049 ha⁻¹). Among nano fertilizers, foliar application of nano DAP @ 4 mL L⁻¹ at 40, 60 and 80 DAS resulted in higher plant height (197.4 cm), number of sympodial branches (31.1 plant⁻¹), total dry matter production (369.86 g plant⁻¹), total number of bolls (46.7 plant⁻¹), good opened bolls (41.9 plant⁻¹), and seed cotton yield (1420 kg ha⁻¹), with gross returns (₹1,20,709 ha⁻¹) and net returns (₹43,049 ha⁻¹). The study faced challenges such as variability in nutrient uptake efficiency and the limited field validation of nano-fertilizers under diverse soil and climatic conditions, which may influence the consistency of results. Nevertheless, it contributes valuable insights by demonstrating that both conventional and nano fertilizers play a significant role in improving growth, yield, and economic returns of Bt-cotton, with 100 % RDNP and nano DAP @ 4 mL L⁻¹ showing promising results for sustainable nutrient management.