Maize Silk-Based Biostimulant Seed Priming Enhances Salt Resilience and Productivity in Zea mays by Upregulating Antioxidant Defenses and Targeted Ion-Transport Genes.
Abstract
Biostimulant-rich plant extracts offer a sustainable agricultural strategy to mitigate plant stress. Two-year field experiments (2024-2025) evaluated maize seed priming with maize silk extract (MSE) at 5%, 10%, and 15% (based on dry weight) under normal (NC, ECe=1.48 dS m⁻¹) and saline (SC, ECe=8.90 dS m⁻¹) conditions. SC significantly impaired photosynthesis, leaf integrity, and nutritional balance, ultimately reducing plant growth and grain yield. These detrimental effects were driven by elevated oxidative stress (superoxide and H2O2) and cellular damage (electrolyte leakage and malondialdehyde). Consequently, stressed plants exhibited basal increases in osmolytes, enzymatic (SOD, CAT, POD, APX, and GR) and non-enzymatic antioxidants, the expression of targeted ion-transport genes (SOS1 and NHX2), and total antioxidant activity. However, MSE seed priming significantly alleviated salinity-induced damage. The 10% MSE concentration emerged as the most effective treatment. Under SC, it remarkably enhanced photosynthesis indicators, leaf integrity, essential nutrient contents, and the K⁺/Na⁺ ratio. Consequently, overall plant growth and grain yield increased significantly. These agronomic improvements were mechanistically linked to a pronounced reduction in oxidative stress and cellular damage. Furthermore, the 10% MSE treatment synergistically boosted osmoregulators, antioxidant compounds, defensive enzyme activities, the expression of these specific ion-homeostasis genes, and total antioxidant capacity compared to unprimed plants. These biochemical and targeted transcriptional enhancements were also observed under NC. Conclusively, seed priming with 10% MSE orchestrates a robust, multi-tiered defense system against salinity stress. This highly effective and sustainable approach maximizes maize productivity in saline environments, ultimately contributing to future global food security.