Potassium and Silicon Nanoparticles Stimulate Photosynthesis and Antioxidant Activity in Citrus aurantiifolia Seedlings Under Drought Stress
摘要
Drought is one of the main abiotic stresses that limit plant growth and productivity. Identifying simple and effective strategies to mitigate its impact is therefore crucial. Potassium and silicon are recognized for their vital roles in regulating water balance and enhancing stress tolerance, and their nanoparticle forms may further amplify these effects. In this study, we examined how foliar application of potassium nanoparticles (K-NPs, 150 mg L⁻1) and silicon nanoparticles (Si-NPs, 20 mg L⁻1), applied individually or in combination, influenced the drought tolerance of acid lime seedlings. The combined treatment showed significant improvements in growth, photosynthetic rate, transpiration, and water-use efficiency. These physiological gains were supported by higher nutrient uptake, chlorophyll concentration, and accumulation of carbohydrates, phenolics, flavonoids, tannins, and essential oils. Enhanced antioxidant activity and balanced phytohormone levels, particularly increased gibberellins and reduced abscisic acid, also contributed to stress mitigation. Overall, foliar application of K‑ and Si-based nanoparticles helped acid lime seedlings maintain better physiological and biochemical performance under drought conditions, suggesting their potential as a promising strategy to improve drought tolerance and productivity in water-limited environments.