Abstract
Silicon (Si) is recognized as a beneficial element that enhances crop growth and productivity under both optimal and stress conditions. Increasing cotton productivity using sustainable strategies hold great promise amidst unprecedented climatic challenges. Here, we investigated the comparative effects of two soil-applied Si sources e.g., sodium metasilicate (MS), and silicic acid (SA) on upland cotton. Five treatments namely, 1 mM and 2 mM of both MS and SA, along with a water-treated control (no Si) were applied. Results showed that both MS and SA, applied at seedling stage, significantly improved plant biomass and key physiological traits like relative water content and total chlorophylls compared with the control. Notably, 2 mM MS treatment led to substantial enhancements in fiber yield and quality, increasing lint weight by 47%, seed weight by 47%, and staple length by 11% relative to Si-untreated control. This treatment aslo promoted the highest uptake and accumulation of silica (91%), which was associated with improved uptake of essential soil nutrients—nitrogen (37%), phosphorus (32%), potassium (64%), calcium (25%), magnesium (21%), and a 49% increase in K
+
/Na
+
in cotton leaves in comparison with that of Si-untreated plants. Correlation matrix and principal component analysis revealed that both 1 mM and 2 mM MS, as well as 2 mM SA, significantly contributed to enhanced growth and yield of cotton primarily through increased acquisition of major nutrient elements from soils. These findings provide a foundation for formulating suitable Si supplementation regimes to promote sustainable cotton production with greater nutrient use efficiency at field scale.