Optimized application strategy of Nitrogen-Silicon (N-Si) fertilization improves nitrogen metabolism, grain yield,...

Significant efforts have been devoted to assessing the effects of nitrogen (N) fertilization or silicon (Si) addition on plant growth yield. However, their combined effects were not well documented, especially of rice under dry cultivation. In this study, we examined the effects of N addition (N₀, 0; N₁, 130; N₂, 160; N₃, 190 kg·ha^-1 of N) on the N content, growth, photosynthetic characteristics, nitrogen metabolism, elemental content, and yield of rice under dry cultivation with or without Si incorporation (45 kg·ha^-1).

Based on the average results of two years, silicon application increased the yield of rice under dry cultivation by 36.19% and 16.71% with the addition of silicon in N₁ and N₂ treatments, respectively. Silicon application enhanced agronomic traits of rice under dry cultivation, effectively alleviated the growth and development deficiencies due to nitrogen deficiency under low and medium nitrogen conditions, and delayed the reduction in plant height and leaf area during the filling stage, which in turn improved the photosynthetic capacity. Silicon application also boosted the activity of key nitrogen metabolism enzymes in rice under dry cultivation. This, in turn, promotes the increase in nitrogen-containing substances in plants at different nitrogen levels, supporting nitrogen transport and accumulation of rice under dry cultivation. In conclusion, our findings demonstrate that adding silicon alongside nitrogen fertilizer supports plant growth, especially under low and medium nitrogen conditions, by enhancing the uptake and utilization of both nitrogen and silicon, ultimately increasing yield.