Effect of Nitrogen and Phosphorus on Yield and Yield Attributes of Rice (Oryza sativa L.)

This study investigated the effects of nitrogen (N) and phosphorus (P) fertilization on the growth, yield, and yield-related attributes of rice (Oryza sativa L.) under submerged conditions at Yezin Agricultural University, Myanmar. The experiment utilized a factorial randomized complete block design, testing four N levels (0, 43, 86, and 129 kg N ha⁻¹) and four P levels (0, 6, 12, and 18 kg P ha⁻¹), with three replications during both dry and wet seasons using the Sin Thu Kha rice variety. Results showed that increasing N levels significantly improved plant height, tiller number, SPAD readings, and yield components in both seasons, with maximum yields achieved at 129 kg N ha⁻¹. Phosphorus application also positively influenced growth and yield parameters, though its impact was less pronounced than N, with optimal results observed at 12–18 kg P ha⁻¹. Significant interaction effects between N and P were noted across most parameters, highlighting synergistic nutrient interactions. Notably, N and P had a stronger influence on grain yield during the wet season compared to the dry season. The highest grain yield was obtained with 129 kg N ha⁻¹ and 18 kg P ha⁻¹, highlighting the importance of balanced fertilization for maximizing productivity. These findings offer practical guidelines for optimizing fertilizer use in Myanmar's rice production and emphasize the need for integrated nutrient management tailored to seasonal variations.