Antioxidant Enzyme Responses to NaCl Stress in Cassia angustifolia

Seeds of Cassia angustifolia Vahl. were subjected to 0, 20, 50, 100 mM NaCl for 7 d in order to study the effect of salt stress on growth parameters, endogenous Na⁺ and Cl^– concentrations, antioxidant system, lipid peroxidation, hydrogen peroxide, and proline contents. Salinity affected all of the considered parameters and caused a great reduction in plant biomass. The root and shoot length, fresh and dry mass and germination percentage were inhibited by NaCl treatments. These changes were associated with an increase in the Na⁺ and Cl^– contents in the seedlings and increased activities of superoxide dismutase, catalase, peroxidase, and polyphenol oxidase. The increased enzyme activity coincided with decreased ascorbate content and enhanced H₂O₂ and proline content.