Silicon-mediated alleviation of salinity stress in wheat is linked to reduced sodium accumulation but depends on cultivar and silicon source

Abstract Background and aims Soil salinity constrains crop productivity globally, yet mitigation strategies often involve economic or environmental trade-offs. Silicon (Si) supplementation is a potential approach to alleviate salinity stress, although responses are inconsistent and may depend on Si source and plant genotype. This study aimed to quantify growth responses of contrasting wheat cultivars to salinity and evaluate whether different Si sources modify these responses by reducing sodium (Na + ) accumulation. Methods Ten wheat cultivars were grown under saline or non-saline conditions and treated with one of three Si supplementation regimes: granular amorphous Si, liquid amorphous Si, and liquid potassium silicate. Plant biomass and foliar Si and Na + concentrations were measured and compared with non-supplemented plants. Results Salinity reduced root and shoot biomass by approximately 36% and 26%, respectively, across cultivars, with substantial cultivar variation in sensitivity. Si-mediated mitigation of salinity-induced biomass loss was strongly dependent on cultivar and Si source, ranging from substantial growth improvements (+ 114% and + 133% in roots and shoots, respectively) to neutral or negative responses. Liquid Si formulations provided the most consistent alleviation of salinity-induced biomass loss. Where effective, Si supplementation reduced shoot Na + accumulation under saline conditions and there was a negative correlation between foliar Si and Na + in five of the ten cultivars. Conclusion Si supplementation mitigates salinity stress in wheat, potentially by reducing Na + accumulation, but its effectiveness depends on both cultivar and Si source. Liquid Si offers more consistent short-term benefits. Cultivar selection with targeted Si management may therefore underpin crop resilience to salinity.