Co-application of salicylic acid and potassium induce salinity tolerance by modulating ion homeostasis, chlorophyll pigments and photosynthetic apparatus in wheat

Salinity is a major abiotic stress limiting global agricultural productivity, particularly affecting the physiological functions, nutrient uptake, and gas exchange processes of crops like wheat (Triticum aestivum L.). As salinization of arable land continues to expand, identifying effective and sustainable mitigation strategies is critical. This study evaluated the impact of foliar-applied salicylic acid (SA) (0, 0.01, 0.02, and 0.03%) and potassium (K) (0, 0.05, 0.1, and 0.15%) at two key growth stages (vegetative and grain filling) on two wheat varieties (WL-711 and Kohistan-97) grown under saline (120 mM NaCl; ≈12 dS/m) and non-saline conditions in a controlled pot experiment. Results showed that foliar application of SA (0.02%) and K (0.1%) significantly improved leaf nutrient concentrations (N, P, K, Ca, and Mg) and enhanced photosynthetic pigments (chlorophyll a, b, total chlorophyll, and carotenoids) under salt stress. These treatments also alleviated the adverse effects of salinity on gas exchange parameters, with WL-711 displaying higher tolerance than Kohistan-97. Overall, exogenous application of SA and K effectively improved physiological resilience and nutrient homeostasis in salt-stressed wheat. Notably, this study demonstrates, for the first time, the synergistic effect of optimal foliar doses of SA and K at two critical developmental stages, offering a practical and low-cost strategy to mitigate salinity stress in wheat. The findings provides a valuable basis for future field-scale interventions to enhance wheat productivity in salt-affected regions.