Mechanisms of silicon as a key modulator of maize defense under water deficit: Meta-analytical insights

Drought stress is one of the most critical abiotic constraints limiting maize ( Zea mays L.) productivity worldwide, a challenge expected to intensify under climate change scenarios. While numerous studies have highlighted the beneficial role of silicon (Si) in enhancing plant resilience to drought, its specific mechanisms and magnitude of effect vary considerably among species and environmental contexts. To clarify these relationships in maize, this study presents the first comprehensive meta-analysis quantifying the influence of Si supplementation on the physiological, biochemical, and morphological responses of maize under water deficit conditions. Thirteen independent studies were compiled, encompassing 410 paired observations across 26 experimental comparisons. Standardized mean differences (Hedges’ g) were computed using random-effects models according to data heterogeneity (I 2 ). The results revealed that Si supplementation markedly decreased oxidative stress indicators such as malondialdehyde (MDA) and hydrogen peroxide (H 2 O 2 ), primarily through the enhancement of antioxidant defense systems, including superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX). Additionally, Si-treated plants exhibited higher concentrations of ascorbic acid, proline, and total phenols, which collectively contributed to maintaining photosynthetic pigment integrity (chlorophylls a, b , and carotenoids) and sustaining gas exchange performance, including net photosynthetic rate ( A ), transpiration rate ( E ), and stomatal conductance ( gs ). These improvements translated into enhanced growth and biomass accumulation under drought stress. Despite the variability among studies, the overall findings confirm the positive influence of Si in activating physio-biochemical mechanisms that alleviate drought-induced damage in maize. This synthesis underscores Si as a promising tool for improving drought tolerance in maize cultivation. Future long-term and field-based investigations are encouraged to deepen understanding of the molecular and hormonal pathways underlying these beneficial effects.