Silicon application promotes rice growth and negatively affects development of Spodoptera frugiperda (J. E. Smith).
Silicon (Si) has been reported to enhance plant resistance against biotic and abiotic stressors and also benefit plant growth. These effects are more pronounced in grass species, especially with soil-applied Si. This study investigated the effects of Si application on rice resistance to Spodoptera frugiperda development and plant vegetative growth. Effects of Si on rice were assessed via soil and foliar applications and compared with untreated plants (control). Si was soil- and foliar-applied as 1% silicic acid solution at a dosage equivalent to 1.4 t Si per ha. After application, leaf material was collected from Si-treated and untreated plants and placed in Petri dishes with individual S. frugiperda neonate larvae, where development was followed to adult emergence and biological parameters recorded. Vegetative growth parameters recorded in rice plants were the height, chlorophyll content, fresh and dry weights of shoots, and shoot Si content. No effects of Si application were observed on the durations of larval and pupal stages, larval and pupal survival, and sex ratio of S. frugiperda. Insects fed leaves from Si-treated plants exhibited lower leaf consumption, larval and pupal weights, longevity of males and females, number of eggs, and egg viability. The negative effects were correlated with higher rice Si content. Si application to rice increased plant height, chlorophyll content and dry weight. Our study demonstrates that foliar-applied Si is as efficient as soil-applied Si in negatively affecting S. frugiperda development and providing beneficial effects on rice plant growth.