Study On Water Physiology And Drought Assessment Of Some Landscape Trees In Hohhot

Water shortage has become a global problem. Especially in arid and semiarid areas in China, water shortage has affected social and economic development. In recent years,with the development of economy, the improvement of living standards, urban area is constantly expanding, the urban green space area is increasing. It has become an important measure of urban civilization progress and sustainable development ability index. With the increase of urban green space area, and urban greening water consumption is rising, the contradiction increasingly prominent between the urban greening water and water tension. So using water-saving and drought tolerant tree species is an effective way to save water. It is also the most direct and effective way in the construction of water-saving city green space. In this paper, 13 kinds of garden tree species which is green space usage larger were as the research object in semi-arid area in Hohhot. To study the photosynthetic rate, transpiration rate, water use efficiency, water potential, PV curve and its physiological and ecological indexes such as water parameters. And analysis of the test tree species drought resistance and water physiological ecology characteristics. By membership function method, the multidimensional space coordinate comprehensive evaluation value accumulation method, clustering analysis and principal component analysis（pca） has carried on the comprehensive evaluation of drought resistance about 13 species of landscape plants.And to screen the drought resistance index according to different evaluation methods, to sure drought resistance of reliable indicators and the comprehensive evaluation method which simple and easy to operate. It will be comprehensive evaluation to provide theoretical and practical basis for drought resistance. The results of the study are as follows:（1）The evaluation of drought resistance and reliable water parameters:Which may reflect the beginning of water absorption and water retention of the plants,the main parameters are Ψ_s^sat and Ψ_清晨.The secondary parameters are Ψ_s^tlp and ε_max.If taking into account the WUE,the main parameters are Ψ_清晨、Ψ_s^tlpand RWCtlp,the secondary parameters are WUE and Ψ_s^sat.（2） A reasonable evaluation method:Which may reflect the beginning of water absorption and water retention of theplants, the evaluation method are multidimensional space coordinate comprehensive evaluation value accumulation method, cluster analysis and principal component analysis.If taking into account the WUE, the evaluation method are subordinate function, cluster analysis, multidimensional space coordinate comprehensive evaluation value accumulation method and principal component analysis.（3） Comprehensive different drought resistance evaluation method, the test sample the order of drought resistance:Which may reflect the beginning of water absorption and water retention of the plants, the order is Sabina chinensis>Buddleja alternifolia>Weigela florida>Tamarix chinensis>Sorbaria kirilowii>Syringa oblate. If taking into account the WUE, the order is Pinus tabuliformis > Platycladus orientalis > Sophora japonica > Rhus typhina >Euonymus bungeanus > Prunus ansu > Prunus davidiana.