Funneliformis mosseae and selenite synergistically enhance rice tolerance to soda saline-alkali stress via regulating photosynthetic-ionic homeostasis and GSH-Px/GSH system

Soda saline-alkali soils severely limit rice productivity. While arbuscular mycorrhizal fungi (AMF) and selenium (Se) are known to alleviate abiotic stresses, their synergistic interaction during critical growth stages remains underexplored. In this study, a pot experiment was conducted using natural soda saline-alkali soil to explore the interactive impacts of Funneliformis mosseae inoculation and selenite application at different growth stages. The results showed that selenite application at the booting stage combined with F. mosseae treatment (F Se4 ) significantly enhanced the saline-alkali tolerance of rice ( P < 0.05), with a 20% increase in yield compared to the control treatment (CK). Mechanisms enhancing rice's saline-alkali tolerance included: (i) optimizing photosynthetic efficiency, with increases in C i-D , T r-D , and P n-D of 30.7%, 70.1%, and 70.3%, respectively, and a 130% increase in G s-D compared to CK; (ii) regulating ion homeostasis, with significant increases in K + , Ca 2+ , and Mg 2+ contents in leaves and roots, and decreased Na + content, maintaining higher K + /Na + , Ca 2+ /Na + , and Mg 2+ /Na + ratios; (iii) activities of antioxidant enzymes (SOD, POD, CAT, APX, LAP, GSH, and GSH-Px) showed significant increases relative to CK, with the largest response observed for GSH-Px ( P < 0.05); and (iv) enhancing membrane lipid protection, with Pro content in leaves reaching 97.8 μg/g, and MDA accumulation reduced by 45.5%. This study identifies booting stage as the critical window for selenite- F. mosseae synergy, where GSH-Px/GSH system activation and photosynthetic-ionic homeostasis coordination form a dual protective mechanism against soda saline-alkali stress. These findings provide an innovative theoretical framework and practical strategy for rice cultivation in saline-alkali soils. • Combined selenite- F. mosseae application at different growth stages significantly enhances rice saline-alkali resistance. • Co-application of F. mosseae and selenite optimizes rice physiological traits. • Booting stage selenite application in combined treatment exhibits a significant interactive effect. • Synergistic interaction at the booting stage elevates rice yield by 20% relative to CK under saline-alkali stress ( P < 0.05).