Analysis on the Physiological Characteristic of Populus euphratica with Different DBH under Drought Stress

In order to study drought tolerance of Populus euphratica with different dbh,the contents of leaf chlorophyll,water,soluble sugar,the contents of proline,protein of lower leaves of Populus euphratica of typical communities were researched.The results showed that the contents of carotenoid(Car),carotenoid/chlorophyll,soluble sugar and protein of Populus euphratica with aggravating of different dbh increased when they suffers drought stress.But with aggravating of different drought stress,the contents of chlorophyll b and praline of Populus euphratica with different dbh were decreased,when they suffer a slight drought stress,the contents increased,but when they suffer a severe drought stress,the contents deceased sharply.Every kind of physiological index of Populus euphratica increased with dbh being greater.The conclusion was drawn as follows: under a certain water stress Populus euphratica continually could adjust its drought tolerance,under a certain water stress physiological activity of Populus euphratica will be destroyed.And the greater the dbh of Populus euphratica is,the stronger its drought tolerance will be.