Effect of Salinity Stress on Enzymatic Antioxidants Defense System of Two Maize (Zea mays L.). Varieties

Maize is an economically important cereal crop cultivated worldwide depending on suitable climate condition. maize production is hindered by biotic and abiotic factors. Salinity is one of the major factors that affect maize yield. Plant respond to salinity by changes in their antioxidant enzymes activities which include Catalase (CAT), Superoxide dismutase (SOD), Peroxidase (POX), ascorbate peroxidase (APX) and glutathione reductase (GR). In the present study, maize seedlings were subjected to salinity stress at a different concentrations of 50 mM, 100 mM and 150 mM NaCl and were watered regularly with normal pure water. Root, mature leaves and young leaves were collected after 21 days of sowing and antioxidant enzyme activities in the collected samples were assayed using enzymatic method. A significant (P<0.05) increase in MDA and H2O2 concentration was observed in the roots and young leaves for NaCl-treated samples as compared to the control. Activities of CAT increased significantly (P<0.05) in all organs (root, mature leaves and young leaves) of salt treated maize seedling, while SOD and POX increased specifically in mature leaves. This indicates a possible role of reactive oxygen species (ROS) in the systemic signalling from roots to leaves, allowing leaves to activate their defence mechanism for better protection against salt stress.