Foliar Silicon Application at Multiple Growth Stages Can Improve Lodging Resistance, Yield, and Grain Quality in Rice.

Silicon is an essential element for enhancing the yield, quality and lodging resistance of rice, which are mainly applied through a base application or foliar application during critical growth stages in current practice. The effect of foliar application of water-soluble silicon fertilizer at different growth stages on rice yield, quality and lodging resistance were studied to screen the optimal spraying period that enhances both high yield and lodging resistance. The experiment used "Nanjing9108 and Nanjing5718" as test materials; three treatment combinations were established, corresponding to the following spraying periods: tillering stage + elongation stage (Si1), tillering stage + elongation stage + grain-filling stage (Si2), elongation stage + grain-filling stage (Si3). Applying with plain water served as the control (CK). The results showed that a foliar application of silicon fertilizer significantly increased rice yields, with the Si2 treatment yielding the best results, increasing the yields of the NJ9108 and NJ5718 by 4.82-5.70% and 4.02-5.29%, respectively, over the two-year period. Foliar silicon fertilization significantly enhanced stem wall thickness and shortened the length of the basal internodes, thereby enhancing the lodging resistance of rice. The lodging resistance of the second basal internodes by 5.52-7.79% for NJ9108 and 4.80-7.15% by NJ5718, while that of the third basal internodes increased by 3.42-4.97% and 5.67-6.76%, respectively. In addition, silicon application treatments exhibited enhanced N uptake at maturity with increases of 6.19-13.56% and 5.37-13.86%, respectively. N use efficiency increased with the number of silicon applications. Silicon application during the grain-filling stage effectively delayed leaf senescence, providing sustained photosynthesis to support dry matter accumulation during the mid-to-late growth stages and further facilitating nitrogen transport and utilization. In summary, the synergistic application of silicon fertilizer during the tillering, elongation, and grain-filling stages is the most effective strategy for achieving the dual objectives of high yield and lodging resistance.