Study On Drought Resistance Of 4 Ground Cover Plants

Using Iris milesi,Vinca major var.variegate,Potentilla flagellaris and Nepeta cataria grown in pots as test materials,the effects of drought stress on growth,physiological,pigment content and photosynthetic characteristics of the four species were studied to understand the difference between the four species in respect of drought tolerance ability and to provide the application of the four species and taking appropriate management measures in landscaping and cultivation with the guidance.The results showed that with increasing degree of drought stress the relative growth rate of all four tested plants decreased,with the highest relative growth rate for Potentilla flagellaris and lowest one for Vinca major var.variegate,both the leaf thickness and chlorophyll content also decreased,with the largest decreasing extent for Nepeta cataria and the smallest one for Vinca major var.variegate.Under drought stress condition carotenoid content,the ratio of chlorophyll(a)to chlorophyll(b)contents and the ratio of carotenoid to chlorophylls contents changed a little while soluble sugar and MDA contents and electrolyte leakage rate of the four species increased significantly with relative larger increasing range for Nepeta cataria in soluble sugar content,for Potentilla flagellaris in MDA content and for Vinca major var.variegate in electrolyte leakage rate.The root and SOD activities of Iris milesi and Vinca major var.variegate increased firstly and then decreased during the drought treatment while their POD activity decreased at the beginning and then increased instead.The net photosynthetic rate of the Iris milesi and Vinca major var.Variegata increased at the beginning and then decreased while that of Potentilla flagellaris and Nepeta cataria kept decline during the drought treatment.The average value of membership function for Iris milesi,Vinca major var.variegata,Potentilla flagellaris,and Nepeta cataria is 0.614,0.372,0.533,and 0.521 respectively.A conclusion can be drown from the indexes analyzed and the phenotypes of the plants that the all four tested species can be considered as the plants with more or less strong drought resistance ability,of which the four tested plants are ranked as Iris milesi > Potentilla flagellaris > Nepeta catariaas > Vinca major var.variegata.