From Photosynthesis to Antioxidants: How Silicon (K₂Si₂O₅) Improves Yield and Grain Quality in Rice

Aims Silicon is increasingly recognized as a beneficial element for rice growth, yet limited research has explored how it regulates photosynthesis to influence yield and quality. Methods Through pot experiments and three years of field validation, this study systematically investigated the effects of different silicon concentrations on photosynthetic characteristics throughout the entire growth cycle of rice, as well as on yield and quality parameters. Results The results show that silicon application significantly increased the net photosynthetic rate of leaves at all growth stages and optimized photosynthetic parameters (elevated Fv/Fm, Fv'/Fm', qP, Y(II), and ETR; reduced NPQ). It also enhanced photosynthetic pigment content, improved photosynthase activity and membrane integrity. Additionally, silicon activated the antioxidant defense system, boosting the activity of antioxidant enzymes (CAT and SOD) and stimulating the ASA-GSH cycle, thereby comprehensively enhancing antioxidant capacity. Under field conditions, silicon application significantly increased grain yield and biomass yield while improving quality metrics: reduced chalkiness, optimized starch content and composition, and enhanced processing quality and nutritional value. Notably, silicon treatment increased the content of key aromatic compounds (particularly 2-AP), leading to an overall improvement in quality. These findings indicate that silicon improves yield and quality by enhancing photosynthetic efficiency and strengthening the antioxidant system, with the most pronounced effects observed at 0.75 mM pure silicon (applied as H ₂ Si ₂ O ₅ ). Conclusions The study suggests that strategic silicon application can be an effective approach to ensuring food security and promoting sustainable development in the rice industry.