Field application of silicate suppresses rice insect pest populations and damage in association with defense‐related chemicals

Abstract BACKGROUND It is widely documented that silicon (Si) application plays a crucial role in enhancing crop resistance against pests. However, such effects have been rarely tested in a field context together with varietal resistance and related to defense chemicals. A randomized 2 × 2 factorial combinations of variety [susceptible Taichung Native 1 (TN1) and moderately resistant Zhongzheyou8 (ZY8)] and Si application (treated at 300 kg SiO 2 hm −2 , +Si and untreated, Si) was employed to test the hypothesis that Si amendment interacts with varietal resistance to suppress planthopper populations and damage caused by the rice leaf folder (RLF) and the rice stem borer (RSB) through modulation of defense‐related chemicals. RESULTS The results showed that varietal resistance and Si amendment decreased the overall size of planthopper populations, with ZY8 + Si treatment harboring lower populations than the other treatments. Likewise, both RLF and RSB damage were lower in ZY8 + Si than in TN1 − Si. Chemical analyses indicated that Si supplementation significantly increased plant contents of Si, soluble sugar, carbon:nitrogen (C:N) ratio, cellulose and oxalic acid. Compared with TN1 − Si plants, ZY8 + Si plants had lower N, but higher Si, soluble sugar, C:N ratio, lignin, cellulose, flavonoids, oxalic acid and total phenol. While the accumulation of N was positively correlated to pest population size or damage, the other chemicals each showed an overall negative correlation, with Si accumulation in significant negative correlation. CONCLUSION The current results demonstrate that Si amendment coupled with a resistant variety suppresses planthopper population size and lepidopteran pest damage, which is achieved in association with defense‐related compounds. © 2025 Society of Chemical Industry.