| Salvia miltiorrhiza seedlings were employed to study the effects of exogenous salicylic acid(0.75 mmol/L)treatment on some physical characteristics of S. miltiorrhiza under drought stress, such as relative water content(RWC), electrolyte leakage (EL)，content of H2O2 and malonyldialdehyde(MDA), and activity of superoxide dismutase(SOD), peroxidase(POD), catalase(CAT) and ascorbate perxidese(APX). The results showed that with drought stres, RWC of leaves of S. mitiorrhiza seedlings decreased, and EL, content of H2O2 and MDA increased gradually, however, ex-ogenous SA treatment alleviated these changes. Although the activity of CAT and APX decreased temporally at the begin-ning of SA treatment , the activity of SOD, POD, APX and CAT in the leaves of seedlings treated by SA was higher than that in single drought stress in the subsequent progress of drought stress . Therefore, these results indicated that SA en-hanced the activity of anti-oxidative enzymes in leaves of S. miltiorrhiza seedlings and strengthened the tolerance of S. miltiorrhiza seedlings against drought stress. |