Study of the effect of drought stress on some biochemical and physiological parameters of Lippia citriodora H.B.K.

The application of medicinal plants for the treatment diseases in humans have a long history. It is estimated that more than 10% of the thousands of plant species known to have medicinal uses. Drought causes plants osmotic imbalance and inhibits plant growth and productivity. The aim of this study was to investigate the effect of drought on some biochemical and physiological trait of Lippia citriodora genus of verbeneceae family. Drought stress induced by polyethylene glycol (PEG) with different concentrations, 0%, 5%, 10%,20% and 25%. Result showed that FW (Fresh Wight) and RWC (Relative Water Contents) decreased significantly under drought stress in comparison to control. Root length not show significant changes under drought stress. At low levels of PEG Pigment content under drought stress increased significantly while reduced significantly in high level of PEG. Under drought stress, protein, proline, MDA (malondialdehyd) and hydrogen peroxide (H2O2) contents have been increased significantly. The antioxidant enzyme activity increased under drought stress when compared with control plants. Under drought stress Decreases in some parameter such as FW and RWC indicative sensitivity of this plant to stress on the other hand it responses to stress by increases in some compounds such as prolin, H2O2 and also increases in antioxidant enzyme activity.