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Hibiscus syriacus is a kind of plants,which applies widely to landscape of Beijing in summer,with good ornamental characters and strong drought resistance.It is very important for saving water to construct the botanical garden.At present,the new introducted cultivars have not been applicated widely, they may enrich the landscape of Beijing.so,the studies on the drought resistance of the introduced cultivars of Hibiscus syriacus is significent.On the other hand,the present research of drought resistance of hibiscus syriacus are in the stage of direct-viewing observation and the qualitative description and lacked the research of the physiological biochemistry and systematic analysisUsing a movable rain shelter to keep of precipitation,field experiments on the morphological and physiological-Biochemical characteristics of Hibiscus syriacus L.,which is two yeas old from Shanghai were conducted under different soil moisture treatments.By testing and analysis of many indexes,the results as follows:1、Under water deficit shoot grown,branch growth mass,leaf water content,chlorophyll content, photosynthetic rate and water use efficency.decreased obviously with the increase in treatment intensity, however,The cytomembrance permeability and malondialdehyde（MDA）conient increased.2、The decrease of photosynthetic rate of Hibiscus syriacus was the consequence of stomatal limitation and non-stomatal limitation working together.The processing eary period（0-8th day）,becourse of stomatal limitation,photosynthesizes and intercellular CO2 concentration of hibiscus syriacuses both increase and stomatal conductance reduce.And then,（the 16 days later）,the intercellular CO2 concentration and stomatal conductance of Hibiscus syriacus L.reduce,because non-stomatal limitation is working.The water use efficiency of H15 is higher than others.3、The drought resistance index of eight cultivers of Hibiscus syriacuswas studied under different drought stress,mensurating the physiological drought resistance characteristics such as branch growth mass,leaf water content,chlorophyll content,cytomembrance permeability,MDA content,photosynthetic rate and water use efficency.And a comprehensive evaluation on drought resistance of different cultivars of Hibiscus syriacus L was given based on subordinate function values analysis.Results indicated that the order of drought resistance is:H15>H5>H10>H2>H4>H1>H13>H6.4、According to the comprehensive anlysision for the drought stress and cold hardniss of Hibiscus syriacus,3 cultivars:H1、H3、H15 can be used widely in landscape of Beijing.
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