Physiological Responses of Quercus variabilis Seedlings to Soil Drought Stress

Using the cork oak annual potted seedlings as experimental material,we studied the physiological and biochemical responses of Quercus variabilis seedlings under different soil drought stress systematically by way of weighing to control water content in soil.The result showed:(1)Under the CK stress(relative soil water content is 19.5%~21.5%),SOD,POD and CAT activities in the leaves of Q.variabilis seedlings kept stable,however,under the moderate and severe stress,with the time of drought stress,SOD,POD and CAT activities were increased firstly and then declined.But the ranges were different under different drought degrees.(2)In the whole process,the content of MDA kept an upward trend under different drought degrees,but the ranges were different.In addition,the content of soluble protein and the root activity raised firstly and then decreased with increasing of drought stress.(3)The content of proline become increased firstly and then declined,and the contents of chlorophyll a,chlorophyll b,chlorophyll in total and a/b were decreased in the process of drought stress.It was resulted that Q.variabilis seedlings improved the characteristic of resistance to soil drought stress by increasing the activities of protective enzymes,the content of soluble protein,proline content,root activity and so on in the short time and mild stress.Under severe stress,the metabolism in vivo and self regulation ability were in disorder and deprived,causing the protective enzyme activities,proline content,soluble protein content and root activity decreasing.