Abstract: Physiological and biochemical responses of Potentilla flagellaris and Nepeta cataria grown in pots to drought stress were studied, aiming at understanding drought tolerance ability of the two ground cover plants and their differences in it. The results showed that soluble sugar, soluble protein and proline contents of the two species increased with the aggravating drought degree, with the smaller varied range for that of P. flagellaris. SOD activity of N. cataria had no significant changes under the drought stress treatment but the POD activity appeared a very significant decreasing. SOD activity of N. cataria during the drought stress increased very significantly while the POD activity changed little. Root activities of the two tested plants declined at the beginning and trended to rise afterwards during the drought stress, with the higher activity maintained by P. flagellaris. MDA content of N. cataria in moderate drought stress and that of P. flagellaris in high one had very significant increasing. Based on comprehensive analysis of the indexes and the plants observation, the two tested species can be considered as the plants with strong drought tolerance ability, of which P. flagellaris is more stronger.

Key words: drought stress, Potentilla flagellaris, Nepeta cataria, physiological and biochemical characteristics