Changes in Antioxidant Enzyme Activities in Casuarina equisetifolia Seedlings Under NaCl Stress and Ca~(2+) Regulation in Them

The activities of SOD , CAT and POD and protein concent of Casuarina equisetifolia seedlings underNaCl stress and Ca2+ regulation in them were studied. The results showed that SOD activity decreased, proteincontent and POD activity increased with the treatments of increased NaCl concentration. At the meantime, CATactivity decreased at low NaCl concentrations and increased at high NaCl concentrations. When seedlings weretreated by Ca2+ with proper concentrations, negative effect on protein content and POD activity graduallydecreased, and SOD activity increased. The treatments of Ca2+ enhanced CAT activity when it was low, andweakened it when it was high.