Studies On Drought And Strong Light Resistance Characteristics Of Tamarix Hispida

Ecological conditions are poor in lower reaches of Tarim river, where strong light,high temperature and drought are the main factors affecting survival of plants.Taking Tamarix hispida as study object, this paper determines diurnal variation of chlorophyll fluorescence parameters(Fo, Fm, Fv, Fv/Fm, NPQ), diurnal variation of contents of Car and Chl which are relation with xanthophyll cycle, diurnal variation of active oxygen(O2ˉ,H2O2)and diurnal variation of activity of antioxyenic(SOD,POD)in Tamarix hispida to study the way through which Tamarix hispida dissipating surplus light. Treat the Tamarix hispida which plant in the pot with drought (SRWC 90%,70%,50%,30%,10%),and determine the Contents of osmotic adjustment material,active oxygen(O2ˉ,H2O2) and activity of antioxyenic(SOD,POD,CAT),membran e permeation and the contents of MDA are determined to explore the mechanism of resisting drought in potting planted Tamarix hispida under drought treatment(SRWC 90%,70%,50%,30%,10%).Adaptability of Tamarix hispida under drought stress is analyzed by using the AMD technology to observe variation of microstructure of chlorophyll corpuscle.Main result following:1.The value of Fv/Fm and Fm of Tamarix hispida are decreasing along with increasing of light energy and reaches to the lowest level at 16:00 and then start to rise, showing light inhibition occurs at noon. Along with increasing of light energy,contents of Car,Car/Chl and NPQ are rising, indicating thermal dissipation depending on Xanthophyll Cycle is an important way for Tamarix hispida.Along with the increasing of the light energy,contents of O2ˉare increasing and activity of SOD is increasing too, showing SOD has played a certain role in clearing O2ˉ.Compared with SOD,the role of CAT in clearing O2ˉis very weak.2.The plotting results show that along with SRWC's declining, contents of proline,soluble sugar and soluble protein are increasing. Along with drought stress intensifying,contents of O2ˉand H2O2 are increasing and at the same time activity of SOD,CAT,POD is increasing too. When SRWC is 30%, activity of CAT is decreasing, while activity of POD is still increasing, showing that clearing H2O2 mainly depends on POD when drought stress is serious.Due to co-contribution of osmotic adjustment material and active oxygen in clearing H2O2,only when SRWC drops to 30%,the extent of injure to membrane permeation starts to increases evidently.3. Studies on microstructure of chlorophyll corpuscle show that the number of chloroplast in green branch would reduce,membrane envelop structure would become fuzzy,grana lamella would become loosen,the amount of starch particle would decrease and plascoglobulus would increase when groundwater level reaches 7.68 m, while clasping leaves would show same features only when groundwater level reaches 6.68 m.Along with decreasing of groundwater level,MDA contents of Tamarix Hispida would obviously increase.Therefore the paper comes to a conclusion that the chloroplast in green branch of Tamarix Hispida is more tolerant to drought than that of chloroplast in clasping leaves.When SRWC is 30%,the chloroplast ultrastructure of Tamarix hispida Willd potting planted is collapsing,inferring that the drought stress is very serious.