Phase-specific responses of soil fungal communities to drought stress in cultivated soils

Soil fungal communities contribute to soil health and plant growth by regulating nutrient cycling, decomposing organic matter, and forming symbiotic associations; however, their stage-specific responses to drought remain unclear. To address this, we investigated the effects of drought stress on cultivated soil fungal communities across three summer maize growth stages the jointing-tasseling stage, tasseling-filling stage, and filling-maturation stage. Specifically, we measured the soil properties (soil water content, ammonium nitrogen , accessible phosphorus, available potassium, organic matter, and soil pH) and evaluated their links to fungal dynamics through structural equation modeling and co-occurrence network analysis. Our results demonstrated that drought stress induced highly stage-specific fungal responses. Although dominant phyla (Ascomycota, Mortierellomycota, and Basidiomycota) exhibited robust drought resistance, fungal co-occurrence networks were profoundly restructured. Drought reduced network complexity during the early-to-mid stages, whereas it triggered a massive topological expansion and a drastic loss of stability during the filling-maturity stage. Furthermore, environmental driving mechanisms shifted from a direct moisture-nitrogen coupled constraint in the early stage to an indirect, phosphorus-dominated regime in the late stage. Ultimately, these findings highlight the dynamic ecological adaptations and specific vulnerabilities of the plant-soil microbiome under prolonged drought, providing essential insights for agricultural and ecological management.