The Effection Of Drought Stress On Structure And Physiology Of Four Potentilla Plants

In this paper, four Potentilla plants were chosen as the test material, which are Potentilla chinensis、P. discolor、P. leucophylla and P. verticillaris. The experiment was purposed to research the change of anatomical structure of vegetative organ and the ultrastructure, research the change of photosynthetic characteristics and physiological indicators of leaves with two-year growth under different drought stress. We aimed to establish a drought assessment evaluation system of four Potentilla plants, and provide a theoretical basis for the plants which adapt to the arid environment. The primary research results as follows:1. Under drought stress, the variation tendency of anatomical structure of roots、stems and leaves were generally consistent on four plants. But the changes of Potentilla chinensis and P. discolor were relatively obvious. According to the damage level of the different plants under drought stress, we could be judged for drought resistance ability is that P. verticillaris. better than Potentilla chinensis.2. Under drought stress, the ultrastructures of four plants were changed, but the degree of change is not the same. With the degree of drought stress increases, the damage to the chloroplast of four plants were more and more serious and the size of chloroplast gradually decreases. The chloroplast size changed more obvious than the number of chloroplast. Meanwhile, mitochondrial ridge was fracture, disintegration and vacuolization, but the damage degree of mitochondrial was lighter than the chloroplast. According to the damage level of the different plants on mesophyll cells under drought stress, we could be judged for drought resistance ability is P. verticillaris>P. leucophylla>P. discolor>Potentilla chinensis.3. Photosynthesis is associated with the structural changes of chloroplast. Under drought stress, the structural of chloroplast was changed. So with the drought stress intensifies, leaf net photosynthetic rate, transpiration rate, stomatal conductance and water use efficiency of four plants were gradually decreased, while intercellular CO2concentration had a slight rise.4. With the increasing degree of drought stress, the changes in the physiological indexes of four plants had similarity. Leaf relative water content and chlorophyll content showed a gradual downward trend. The SOD and POD activity were increased first then decreased. MDA, proline and soluble protein content were showed a significant upward trend. According to the change range of the indicators on different plants, we could be judged for drought resistance ability is P. verticillaris>P.leucophylla>P. discolor>Potentilla chinensis.