Comparative studies on the effect of salinity and drought stress on enzymatic antioxidant defense system of two maize (<i>Zea mays</i> l.). varieties

Abstract

Soil salinization and drought are serious threat to crop productivity and predicted to increase in face of global climate change. Studies have shown that as much as the 12 billion US dollar will be lost globally each year, due to the reduction in agricultural production from drought and salt-affected areas. Maize is an economically important cereal crop affected by high salinity and drought stress, maize seedling was subjected to 50 mM, 100 mM and 150 mM NaCl and 4, 6 and 8 days to emulate high soil salinity and drought stress. Root and mature leaves were harvested after 21 days of sowing. High salinity induced oxidative stress in the root and mature leaves. The root and matured leaves showed increased malondialdehyde (MDA) and the hydrogen peroxide (H2O2) concentration at 50, 100 and 150 mM NaCl and 4, 6, and 8 days of drought strss. Activities of enzymatic antioxidants, Catylase (CAT, E .C 1.11.1.6) increase in all organs of salt treated maize seedling, while superoxide dismutase (SOD, 1.15.1.1) and peroxidase (POX, E.C. 1.11.1.7) increased specifically in mature leaves. This indicates a possible role of reactive oxygen species (ROS) in the systemic signaling from roots to leaves, allowing leaves to activate their defense mechanism for better protection against salt and drought stress.