Exploring the role of endogenous and exogenous silicon in reducing arsenic accumulation in rice: A multi-scale hydroponic to field study

Introduction Traditionally, Silicon (Si) fertilizers are applied externally to the soil or sprayed on the leaves to reduce rice’s arsenic (As) accumulation. However, in practical agricultural production, the economic benefits of lowering As in rice grains often fail to outweigh the production costs. Objectives This study investigated an innovative technology—Si-rich seedlings (endogenous Si)—that is simple to implement, cost-effective, and highly effective in reducing As accumulation in rice grains. Methods The effects of exogenous and endogenous Si supplementation on As dynamics in rice were investigated in hydroponics in field experiments. Results Both methods significantly reduced As accumulation in the rice grains (22.23 % and 17.70 %, respectively). There was no significant difference in the treatment effects. However, endogenous Si supplementation demonstrated a significantly lower cost per unit of As reduction (88.61 % decrease), and it was easier to implement when compared with exogenous Si supplementation. The main processes by which various Si treatment techniques decrease As accumulation in rice differed, even though Si was crucial to As absorption in rice through a combination of mechanisms, such as gene regulation, iron plaque inhibition, and node I sequestration. The fundamental mechanism was Si/As antagonism, which regulated Si absorption through gene regulation in both methods. Interestingly, the exogenous Si treatment improved the barrier function of the root surface iron plaque against As. At the same time, laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) demonstrated that endogenous Si had a more pronounced impact on rice node I. Furthermore, experiments conducted at multiple scales (including variety, pot, and field experiments) validated the stability and reliability of the Si-rich seedling technology under complex environmental conditions. Conclusion Si-rich seedlings provide a cost-effective, stable, and practical solution for mitigating As contamination in paddy fields. This approach holds significant potential for enhancing soil health and improving food safety, contributing to the sustainable development of rice cultivation.