Silicon-induced drought resilience in maize (Zea mays L.): uncovering the integrated physiochemical and transcriptomic insights into stress mitigation

Drought stress is a major environmental constraint in maize cultivation, causing substantial yield reductions across agricultural systems. Silicon (Si) has been recognized as an effective mitigator of drought stress in crops. However, the molecular mechanisms underlying Si-mediated drought resistance at different developmental stages in maize remain poorly understood. This study employed a controlled column soil experiment under rain-shelter conditions to systematically investigate Si-mediated drought regulation during three critical growth phases: jointing stage (DV6), tasseling stage (DVT), and filling stage (DR2), through integrated analysis of physiochemical and transcriptomic data. The results revealed that foliar Si supplementation significantly improved both shoot and root growth, and increased photosynthetic parameters and chlorophyll content under drought stress. Exogenous Si application also enhanced the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), which consequently reduced the contents of superoxide radical (O2·−) and malondialdehyde (MDA). Additionally, Si application elevated soluble sugar and protein contents. Yield analysis revealed that the treatments of DV6, DVT, and DR2 significantly decreased maize yield by 16.7%, 96.3%, and 37.4%, respectively compared with the control (CK), whereas Si supplementation substantially mitigated these losses to 3.5%, 67.7%, and 34.7% respectively. Transcriptome analysis revealed differentially expressed genes (DEGs) functionally annotated to photosynthesis, plant hormone signaling, mitogen-activated-protein-kinase (MAPK)-mediated signal transduction, and secondary metabolite biosynthesis pathways. Foliar Si supplementation significantly upregulated the expression of genes related to photosystem I, photosystem II, and light-harvesting chlorophyll protein complex under drought stress compared with non-Si-treated plants. Silicon application reduced the expression of genes encoding abscisic acid (ABA) and jasmonic acid (JA) signaling pathway, while upregulated the expression of genes related to Cytokinins (CKs) and auxin (IAA). In conclusion, silicon supplementation enhanced drought tolerance and promoted maize development by coordinating the regulation of key drought response pathways, including physiological adaptations and regulatory pathway involving plant hormones.