Silicon in agriculture: role, mechanisms, and applications for climate-smart crop production

Silicon (Si), an extremely abundant metalloid in the Earth’s crust, is increasingly recognized as a beneficial element for plants, particularly under escalating abiotic and biotic stresses associated with climate change. This review synthesizes current knowledge on the role of silicon in agroecosystems, focusing on its physiological functions, uptake and transport mechanisms, stress‐mitigating effects, and application strategies relevant to climate-smart crop production. Plants predominantly absorb silicon as monosilicic acid [Si(OH)₄], with root-to-shoot transport mediated by the Lsi1 influx and Lsi2 efflux transporters, while soil pH, texture, organic matter, and temperature strongly regulate silicon solubility and bioavailability. Silicon supplementation enhances plant performance through cell wall reinforcement via phytolith deposition, improved plant–water relations, and activation of metabolic and transcriptional responses. Consequently, silicon improves seed germination, growth, photosynthesis, gas exchange, photosystem efficiency, and yield across diverse cropping systems. Key mechanisms include aquaporin-mediated increases in root hydraulic conductivity, regulation of abscisic acid signaling and stomatal behavior, osmotic adjustment through compatible solutes, and enhanced antioxidant capacity that mitigates reactive oxygen species–induced damage. Silicon also contributes to salinity tolerance by maintaining Na⁺/K⁺ homeostasis, improves resistance to temperature extremes and heavy metals, and enhances biotic stress resistance through physical barriers, defense priming, secondary metabolite accumulation, and modulation of rhizosphere microbiomes. Soil, foliar, hydroponic, and seed-priming applications are effective delivery pathways but require optimization of source, rate, crop specificity, and safety. Overall, silicon fertilization represents a promising, context-dependent tool to enhance crop resilience, productivity, and quality, although broader adoption requires improved mechanistic understanding, standardized evaluation, economic validation, and robust regulatory frameworks, particularly for nanoparticle-based formulations.