The foliar potassium silicate enhances wheat terminal-drought tolerance and yield via physiological, biochemical and genetic regulation

Drought stress limits wheat productivity at terminal stage by disrupting physiological activities, impairing cellular homeostasis, and decreasing grain yield. Present study elucidated the role of potassium silicate (K2SiO3) in mitigating drought-induced damage in wheat through integrated physiological, biochemical, agronomic, and molecular approaches. Wheat plants were subjected to terminal drought-stress under four different levels (0, 2, 4, and 6 mM) of K2SiO3. Application of K2SiO3, particularly at 6 mM, significantly improved relative water content, photosynthetic rate, and PSII efficiency. Antioxidant defense system was reinforced through higher SOD, CAT, and POD activities, accompanied by lower MDA and electrolyte leakage. Yield components were markedly increased, with grain yield increasing by 72% relative to control, alongside significant gains in thousand grain weight, grains per spike, and biomass. Gene expression analysis revealed significant upregulation of TaDREB2 and TaNCED1, supporting improved water relations, while TaSOD, TaCAT, and TaAPX1 regulation corresponded with increased antioxidant enzymes activities. Reduced expression of TaP5CS aligned with lower proline accumulation, whereas TaBADH upregulation was consistent with increased GB content. Moreover, TaLEA upregulation supported membrane stability, and yield-related genes TaCKX2 and TaGW2 expression improved spike fertility and grain weight. These results demonstrated that K2SiO3 treatment activates multiple drought tolerance mechanisms that integrate gene regulation, osmotic adjustment, antioxidant defense, and yield stabilization. Overall, the findings establish application of K2SiO3 especially at 6 mM, as an effective strategy for enhancing drought tolerance and sustaining the productivity of drought susceptible wheat cultivar (Galaxy-2013) at terminal stage of drought stress.