Abstract
Drought is one of the major threats to potential yield of crop as it strongly impair growth both at vegetative and reproductive stage leading to decrease in yield and productivity. Thus, identification of the key system in drought tolerance is essential for better crop yield. Roots of two maize varieties i.e. Azam and Baber were evaluated in this study based on the enzymatic defence system. The withdrawal of water for 7 days, the roots of the drought stressed plants not only exhibited reduction in fresh weight but also total soluble proteins were deceased by more than 50 % in comparison to well watered. Cations such as Na+ , K+ and Ca+ were also strongly accumulated. Moreover, the huge accumulation of more than 2-fold in H2O2 and MDA contents in both varieties upon water deficiency indicating that roots experienced severe oxidative stress. In response to drastic increase in Reactive Oxygen Species (ROS), the enzymatic based defense system actively enhanced to minimize the detrimental effect of ROS. Almost all the enzymes including APX, CAT, SOD and POD were increased 1.4- to 2-fold in roots of drought-stressed plants. Thus, plants with strong scavenging mechanism can be used as an important indicator for drought tolerance.
