Silicon Dioxide Nanoparticles Regulate the Growth, Antioxidant Response, and Nitrogen Metabolism of Fragrant Rice Seedlings under Different Light and Nitrogen Conditions

Nanoparticles have been widely used in agriculture, but few studies have reported the effect of silicon dioxide nanoparticles (SiO2NPs) application on rice growth. This study is the first to investigate the effect of SiO2NPs on rice under the interaction of light and nitrogen. This study aimed to investigate the effects of SiO2NPs on the growth, antioxidant response, and nitrogen metabolism of rice seedlings under different light and nitrogen conditions. Two fragrant rice cultivars, Meixiangzhan 2 and 19 Xiang, were grown under four SiO2NPs concentrations (SiO2NPs at 0 mg L-1, 50 mg L-1, 100 mg L-1, and 500 mg L-1) and four light and nitrogen levels. The results showed that the application of SiO2NPs significantly affected root and shoot length, total fresh weight, dry weight, and some physiological parameters. The application of SiO2NPs resulted in changes in growth and physiological parameters, which varied with different light and nitrogen levels. The total dry weight significantly increased after the application of SiO2NPs at 50 mg L-1 under normal light and nitrogen conditions by 28.95% and 15.81% for Meixiangzhan 2 and 19 Xiang, respectively. In addition, the application of SiO2NPs modified the superoxide dismutase activity, nitrate reductase activity, soluble protein content, and hydrogen peroxide content under different light and nitrogen conditions. The correlation between the investigated parameters under the application of SiO2NPs at different light and nitrogen levels was assessed. Overall, this study suggested that the application of SiO2NPs alleviates light stress and nitrogen deficiency stress by regulating soluble protein content, nitrite reductase activity and the antioxidant reaction system, thus promoting rice growth. This study provides theoretical support for the application of nano-fertilizer technology and SiO2NPs to alleviate low light stress in rice.