Physiological Response of Magnolia wufengensis 'Jiaohong 1' to Water Stress

One-year-old grafted seedlings of Magnolia wufengensis 'Jiaohong 1' were used as test materials. The potting soil water content was set as 20%(HD), 40%(LD), 60%(CK), 80%(LF), 100%(HF) of the maximum field water capacity(FWC), and the photosynthetic characteristics and physiological indexes of 'Jiaohong No. 1' leaves were measured under different treatment conditions. The results showed that: under water stress, all the 'Jiaohong 1' seedlings under HD treatment died on the 10th day of stress(the survival rate of the rest was 100%), the chlorophyll content of the 'Jiaohong 1' leaves in the CK treatment group decreased first and then increased, and the rest treatments decreased with the extension of stress time. The diurnal variation of P_n and G_s showed a double peak phenomenon, the diurnal variation of T_r showed an upward trend and then a downward trend, the diurnal variation of C_i showed an upward trend, and that of WUE and L_s showed a downward trend. The daily mean values of P_n, G_s, C_i and T_r under CK treatment were the largest, while those of WUE and L_s under HF treatment were the largest. With the extension of stress time, the contents of soluble sugar, soluble protein and MDA in the leaves of 'Jiaohong 1'seedlings increased first and then decreased. The content of Pro and activity of SOD showed an upward trend.The activity of APX decreased first, then increased and then decreased, and the activity of APX was the lowest under CK treatment when the stress was maintained to the 40th day. In the study, 60%～80% FWC is the best condition for the growth of Magnolia wufengensis'Jiaohong 1'.