Mechanistic study on integrated water-fertilizer management to alleviate Na+ toxicity and enhance salt tolerance and yield of pakchoi under salt stress.

The cultivation of salt-tolerant pakchoi is a promising strategy for utilizing coastal saline soils. However, supporting agronomic technologies are remain underdeveloped. This study investigates how coordinated water-fertilizer regulation mitigates sodium (Na+) toxicity under salt stress, thereby enhancing salt tolerance and yield in pakchoi and providing a scientific basis for optimizing agronomic management. A pot experiment was conducted with three irrigation methods (conventional, drip, and mulched drip) and three fertilizer types (conventional, controlled-release, and mixed), under soil salt stress adjusted by sodium chloride (NaCl) to 0.15% salinity by weight. The results showed that MP treatment (mulched drip irrigation + mixed fertilizer) can significantly improve yield performance, with fresh and dry weight increasing by 39% and 42% respectively, and enhancing ion balance by increasing potassium (K+) and calcium (Ca2+) and reducing Na+. In addition, MP enhanced antioxidant defense by increasing superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX) activities and reducing oxidative damage. The treatment also maintains better water status and photosynthetic efficiency. MP treatment can improve growth, physiology, and stress tolerance. This integrated approach represents a novel water-fertilizer strategy with high application potential for sustainable vegetable production in saline regions.