Silicon at the Frontline: Enhancing Plant Multistress Tolerance

Abstract The intensity of climate change has increased in recent years, intensifying multiple environmental stresses, including water-related stresses (drought, flooding), ionic and chemical stresses (salinity, nutrient and metal toxicities), temperature extremes, and radiation stress. This climate-induced increase in stress severity has led to the development of combined stress conditions that worsen their negative impacts on agricultural productivity and present a critical hazard to the stability of the global food supply, particularly with the increasing population. Primarily, current research has been largely directed towards developing practical strategies aimed at improving crop tolerance to individual stress conditions. Nevertheless, addressing the challenges posed by simultaneous stresses is of paramount importance for ensuring sustainable crop production. Among these, the application of silicon (Si) has been demonstrated to improve plant tolerance to various abiotic stresses through a range of physiochemical, physiological, and transcriptomic mechanisms. The present review discusses the involvement of Si in mitigating both individual and combined stress conditions. Furthermore, the underlying mechanisms influenced by Si application are examined, including its involvement in hormonal regulation, gene expression, and the potential contribution of silicate fertilization to carbon sequestration. At the mechanistic level, Si enhances plant stress tolerance by improving root hydraulic properties, water uptake, and photosynthetic performance, thereby maintaining carbon assimilation under adverse conditions. In addition, Si contributes to stress resilience by regulating ion homeostasis and osmotic balance, optimizing nutrient uptake and stoichiometric stability. From a practical perspective, this review demonstrates Si application as a promising strategy to enhance crop resilience under increasing climate-induced individual and combined stresses to be incorporated into sustainable agricultural management practices. Graphical Abstract