Salinization severely impairs crop growth by inducing oxidative stress and disrupting cellular homeostasis. This study systematically investigates the synergistic effects of salt-tolerant plant-growth-promoting rhizobacteria (ST-PGPR) and foliar silicon fertilizer spraying (FSFS) on antioxidant responses in Pak choi under salt stress. Two-season pot experiments were carried out to evaluate key indicators, including antioxidant enzyme activities (superoxide dismutase: SOD; peroxidase: POD; catalase: CAT), oxidative stress (malondialdehyde: MDA), osmolyte accumulation (proline, soluble protein), and hormones (Jasmonic Acid: JA; Salicylic Acid: SA; Abscisic acid: ABA). The results demonstrate that combining ST-PGPR with FSFS significantly enhances SOD (6.18-2353.85%), POD (3.44-153.29%), and CAT (25.71-319.29%) activities while reducing MDA content (8.12-35.87%). Proline and soluble protein levels increased by 1.56-15.71% and 5.03-188.87%, respectively. Hormonal regulation increased JA, SA, and ABA levels by 1.05-31.81%, 2.09-34.29%, and 3.18-30.09%, respectively. Notably, ST-PGPR treatments at 104 and 106 cfu·mL-1, combined with foliar silicon application, consistently ranked highest in overall antioxidant performance across both seasons based on a principal component analysis. These findings provide novel insights into microbial-mineral interactions for sustainable saline agriculture.
Keywords: antioxidant enzyme activation; hormonal regulation; osmolyte accumulation; principal component analysis; sustainable saline agriculture.