Comparative effects of urea and nano-urea on growth and yield performance of transplanted rice in the inner Terai Region of Nepal

Efficient nitrogen management is essential for enhancing rice productivity and nitrogen use efficiency. Overdependence on conventional urea often leads to suboptimal crop response and significant nitrogen losses to the environment. To address this, a field experiment was conducted during the 2023 rainy season in the Inner Terai region of Deukhuri, Dang, Nepal, to assess the effect of integrating conventional granular urea with nano-urea on the growth and yield of transplanted rice (Oryza sativa L., variety Hardinath-6). The study included eight treatments: a control, 100% recommended dose of nitrogen recommended dose of nitrogen (RDN) using ures, and six combinations of 75% or 50% RDN with nano-urea applied at vegetative and/or booting stages. Growth and yield parameters such as plant height, tiller number, panicle length, thousand-grain weight, grain and straw yield, filled grains per panicle, and sterility percentage were measured. The highest grain yield (4.38 t ha-1) was obtained under 100% RDN, while the treatment with 75% RDN + 25% nano-urea applied at the vegetative stage produced a statistically comparable yield (4.16 t ha-1). This treatment also recorded higher straw yield (7.07 t ha-1), longer panicles (23.96 cm), and more filled grains per panicle (198.67). In contrast, treatments with nano-urea alone resulted in lower yields, despite slightly reducing sterility. Overall, the findings indicate that partial substitution of urea with nano-urea, particularly at 25% applied at the vegetative stage, can sustain rice yield and thereby offering a more resource-efficient nitrogen management strategy.