Effects Of Drought Stress On Growth And Physiological Characteristics Of Loropetalum Chinese

The Loropetalum chinense is precious garden greening tree species in China. It is with beautiful tree shape, flowers and leaves and also resistant to clip and easy to shape, so it is widely used in bonsai, garden greening and other fields; but the landscape effect will be greatly affected when it is in drought. In order to find out its physiology of drought resistance, this paper studied the changes of growth, resistance physiology and photosynthesis physiology index of annual Loropetalum chinense seedlings which were cultured in pots in different soil drought conditions (soil moisture were 80%,60%,40%,20% of matrix maximum water holding capacity), which provide the reference basis for the water management and landscape demand of Loropetalum chinense in the process of landscape management, introduction and cultivation. The main results of this study were as follows:(1) Loropetalum chinense became wilting, dry and dead and the growth and blossom of which was inhibited Under drought stress. The phenomenon and inhibition wereobvious with the depth of drought stress degree. there was no phenomenon appearing to the drought at the beginning of the mild and moderate drought stress, but the Loropetalum chinense became dead under severe drought stress. And the moderate and severe drought stress inhibited the blossom ofLoropetalum chinense, which impacted seriously on the exterior of theLoropetalum chinense.(2) The leaves of Loropetalum chinense had a higher RWC which was decline slow under mild and moderate drought stress and decreased rapidly under severe drought stress. RA decreased extremely significantly with stress deepening.(3) The plasma membrane permeability of Loropetalum chinense increased under drought stress. REC raise with the extension of time and the deepening of stress. The MDA content fist increased in the beginning and then decreased after under the mild and moderate drought stress, but which was on an upward trend under severe drought stress.(4) The content of Pro, SS and SP in chinense Loropetalum leaves all increased under drought stress, but there were some differences in the accumulation process with the deepening of stress, which were the accumulation of SS and SP was earlier than that of Pro, and sp accumulation stopped earlier than Pro accumulation.(5) Activity of SOD, POD and CAT in Loropetalum chinense leaves all strengthened under drought stress, but activity of CAT changed little, while activity of SOD and POD changed violently with the stress deepening and There was a reciprocal relationship between them.(6) The content of Chla, after Chlb, Chl and Car in Loropetalum chinense leaves first raise and then decreased under drought stress, but the overall content was increased, while the Chla/Chlb first decline and then raise, which in experimental group was decreased compared with the control.(7) Pn, Tr and Gs of Loropetalum chinense leaves decreased significantly with the stress deepened under drought stress, while Ci dropped fist and then raise with the stress deepening and kept highest in the severe drought stress conditions. WUE raise fast fist and then slowly with the stress deepening, changed little under mild drought stress, increased significantly under moderate drought stress and increased sharply under severe drought stress. There were some certain correlations among the photosynthetic indices, which were the changes of Pn, Tr and Gs trended the same and the change tendency of Ci was consistent with that of WUE.