Positive effects of salicylic acid on some biochemical and physiological parameters of Aloysia citrodora under drought stress

Lippia citriodora H.B.K. is a valuable medicinal plant of Verbenaceae family. This study was calculated to evaluate potential role of salicylic acid (SA) in diminish the harmful effects of drought stress on L. citriodora plants. SA (0.5 and 1 mM) was used to L. citriodora plants grown under stressed (5, 10, 15 and 20% PEG) and unstressed conditions. Fresh weight (FW) and relative water content (RWC) significantly decreased under water deficit stress. Increase in hydrogen peroxide (H2O2) and malondialdehyde (MDA) content indicated drought-induced oxidative stress in L. citriodora. Water deficit stress significantly increased the protein content, proline content and antioxidative enzymes activities. The exogenous application of SA to drought-stressed plants reduced the content of MDA and H2O2 and increased superoxide dismutase (SOD), peroxidase (POX) and chlorophyll content. It is suggested that SA minimizes the negative effects of drought stress and could be used for amelioration of drought stress in L. citriodora.