Electrophysiological sensors reveal silicon–selenium interaction of dynamic leaf intracellular water–nutrient metabolism in rice under cadmium stress

Silicon (Si 4+ ) and selenium selenite (Se 4+ ) exhibit antagonistic effects on cadmium (Cd 2+ ). While plant electrophysiological sensors can quantify intracellular water and nutrient metabolism, the dynamic interactions between silicon and selenium in rice under cadmium stress remain unclear. This study focused on a rice variety (Yixiangyou 876, Enshi, Hubei Province, China), examining growth, photosynthesis, Se and Cd transport, and intracellular water and nutrient metabolism under varying silicon concentrations. Compared to Cd stress alone, the application of MSi (10 mM Si 4+ and 8 μM Se 4+ ) increased rice growth, significantly increasing water transfer rate (WTR), nutrient active translocation capacity (NAC), and nutrient transfer rate (NTR) by 148.57%, 192.01%, and 148.57%, respectively. This synergistic treatment promoted Se translocation and decreased Cd concentration. In contrast, HSi (15 mM Si 4+ and 8 μM Se 4+ ) suppressed rice growth, decreasing intracellular water holding capacity (IWHC) and NAC by 33.21% and 46.52%, respectively. Thus, 10 mM Si 4+ in combination with Se 4+ improved growth, photosynthesis, and intracellular water and nutrient transfer capacity in rice leaves and mitigated cadmium transport. This study provides scientific evidence for Enshi selenium-enriched cadmium-reduced rice. Its core value lies in converting complex physiological processes into quantifiable electrical signals, enabling researchers and farmers to precisely regulate the absorption and metabolism of selenium and cadmium in rice, ultimately achieving the agricultural goal of "high-quality, safe, and efficient" selenium-enriched agriculture.