Exogenous Potassium Silicate Improves Drought Tolerance in Cotton Genotypes by Modulating Growth, Gas Exchange and Antioxidant Metabolism

Cotton is a highly sensitive crop to drought stress. Consequently, it is crucial to devise strategies that optimize crop production in conditions of limited water availability. While potassium silicate has demonstrated effectiveness in mitigating drought stress in various crops, its specific impact on different cotton cultivars under drought conditions remains not fully clarified. This research aimed to assess the efficacy of six potassium silicate levels (0, 100, 200, 300, 400 and 500 mg L⁻¹) on four cotton genotypes (Zong main-113, Xin Nong-525, Xin lu Zhong-55, and Xin lu Zhong-66) under two field capacity levels (80% and 50% FC) in a sand culture. Foliar applied potassium silicate significantly improved photosynthetic efficiency, shoot biomass, root biomass, and leaf area under water stress (50% FC). The most substantial reduction in H₂O₂, malondialdehyde levels, and electrolyte leakage was recorded with potassium silicate applied at a rate of 400 mg L⁻¹. This concentration effectively mitigated reactive oxygen species accumulation, safeguarding plants against oxidative damage at 50% FC. Furthermore, potassium silicate contributed to maintaining water status, resulting in increased leaf water content and elevated water-soluble proteins in cotton plants. The order of drought resistance (50% FC) with the application of potassium silicate at 400 mg L⁻¹ was Zong Mian-113, Xin Nong-525, Xin lu Zhong-55, and Xin lu Zhong-66. The findings could help in selection of drought resistance cultivars of cotton in water limited conditions.