Differential Modulation of Antioxidant Defense and Salinity Tolerance in Maize by Selenium, α-Tocopherol, and Ascorbic Acid

Selenium, α-tocopherol, and ascorbic acid are important antioxidants that mitigate abiotic stresses in plants, yet their comparative effects under salinity remain insufficiently studied. This study aimed to evaluate and compare the effects of selenium, α-tocopherol, and ascorbic acid on growth, carbon metabolism, and ion uptake in salt-stressed maize plant. Deionised water (control), selenium (0.5 mM), α-tocopherol (200 ppm), or ascorbic acid (500 ppm) were applied to maize seeds, which were then cultivated at NaCl concentrations of 0, 100, 150, and 200 mM. Plant samples were examined for ionic, physiological and biochemical characteristics after 40 days. Salt stress caused concentration-dependent reductions in growth, chlorophyll, insoluble sugars, carbohydrates, phenolics, flavonoids, and ion uptake, while enhancing soluble sugars, α-amylase activity, and sodium accumulation. On the other hand, growth performance, pigment content, carbohydrate and secondary metabolites, and the K⁺/Na⁺ and Ca²⁺/Na⁺ ratios were all improved by antioxidant treatments administered in non-stressful environments. Among the tested compounds, ascorbic acid was most effective in alleviating salt-induced damage. It enhanced antioxidant activity, improved carbon metabolism and ion homeostasis, and induced proteins linked to salt tolerance, leading to better growth under salinity. In conclusion, ascorbic acid shows promise as a way to reduce salt stress and increase maize yields in salty soils.