The Study On The Drought Resistance And Heat Resistance Of Four Kinds Of Sedum Plants For Roof Greening

This paper had chosen four kinds of sedum plants as the research objects which were Sedum lineare,Sedum reflexum,Sedum spectabile and Sedum spurium "Coccineum". The research made two experiments, one observed the plants morphology and studied physiology and biochemistry features when the plants were under drought stress; the other was to compare the heat resistance. The main results were shown as follows:1. Drought stress had an effect on the morphology of plants. In the early days on drought stress, plants grew up slowly; during the middle stage, the leaves began to lose water and wilt, and the leaves of Sedum lineare and Sedum spurium "Coccineum" changed obviously; late under drought stress, the leaves of Sedum spurium "Coccineum" and Sedum reflexum wilted seriously, and began to dried-up and fall off, but Sedum lineare and Sedum spectabile had relative small changes.2. Soil water content changed obviously under drought stress. During the early and middle stages soil water content went down rapidly whereas it went down slowly and gradually during the later stages. The decline of water content in leaves was small, and the dehydrating rate of Sedum lineare in leaves was the lowest and that of the Sedum spurium "Coccineum" is the highest.3. With the increasing time of drought stress, the relative electric conductivity in leaves went up slowly with the Sedum spurium"Coccineum"rising the highest and the other three relatively slowly. The soluble protein content in leaves presented the trend that first increased then decreased, the increase of Sedum spectabile was the highest, the next were Sedum lineare and Sedum reflexum, the Sedum spurium "Coccineum" was the lowest. The MDA content in leaves of Sedum spectabile and Sedum reflexum increased slowly and that of Sedum spurium "Coccineum" increased rapidly. The content of free proline in leaves increased gradually, Sedum spurium "Coccineum" changed slowly and Sedum lineare increased more obviously. The SOD activity of four kinds of plants all presented the trend that first increased and then decreased. The soluble sugar content began to reduce at first ,but increased after 10 days under drought stress.4. Adopting the relative electric conductivity method, the paper studied the heat resistance of plants. According to the half lethal temperature, the order of the strengths and weakness of heat-resistance of four kinds of plants were: Sedum spectabile>Sedum lineare >Sedum reflexum>Sedum spurium "Coccineum".