Studied On Drought Tolerance Of Reaumuria Soongorica In Different Geographical Population Under Water Gradient

Using Reaumuria soongorica which are ultra-xeromoph shrub as materials,this paper analized the difference of biomass and Leaves physiological characteristics of Reaumuria soongorica in different geographical population from the east to the west . Meanwhile,physiological responses of Reaumuria soongorica,comparing with caragana korshinkii and nitraria sibirica was studied. The mechanism of drought tolerance was disscussed. Main result were as follow:1. The biomass of Reaumuria soongorica in different geographical population under different water gradient studied showed that: with water gradient decreasing from east to west, all the shape index and biomass were decreasing. However,one-year branches weight of WuWei were lighter than JiuQuan and ZhangYe. From the regressional equation of shape index,biomass and relative humidity ,it ingdicated that there was a close relationship between shape index,biomass and relative humidity.2. With water gradient decreasing from east to west, the activities of superoxide dismutase (SOD),peroxidase (POD)and catalase(CAT) increased while the content of malondialdehyde ( MDA) and O-?2 production rate increased, but the activities of superoxide dismutase (SOD),peroxidase (POD) and catalase(CAT) decreased at jiuquan. Meanwhile, the contents of osmoregulatory substances such as free-proline and soluble sugar increased. Expect WuWei,the change of Chlorophyll a and chlorophyll b content was not significant.3.Comparative physiological responses of Reaumuria soongorica and caragana korshinkii and nitraria sibirica under PEG osmotic stressed. Study showed that: the decrease of Reaumuria soongorica's relative water content was less than others two shrubs, but its potential decrease more rapidly than others shrubs. Reaumuria soongorica could preserve water most efficiently and kept more bond water than other two shrubs. The increasing rate of proline of Reaumuria soongorica was higher than that of caragana korshinkii and nitraria sibirica. The Soluble sugar content of Reaumuria soongorica was also increased more rapdily than caragana korshinkii and nitraria sibirica during PEG osmotic stressed. SOD and POD activity of Reaumuria soongorica kept increasing. Its CAT activity increased under low concentration of PEG osmotic stressed. However,it decreared when deeper osmotic stressed. With the PEG osmotic stressed increasing, Chla content of Reaumuria soongorica leaves on top of mountain was increaring at first and then decreased,but Chlb was decreased. Both of Chla and Chlb content of Reaumuria soongorica leaves on bottom of mountain were decreased.The MDA content enhanced with the deeper of PEG osmotic stressed, the degree of membrane injury of caragana korshinkii was deeper than Reaumuria soongorica and nitraria sibirica. O₂^-· generation rate of Reaumuria soongorica and caragana korshinkii on top and bottom of mountom were increased,then decreased, but nitraria sibirica were decreased frist,then increased.Principal component analysis: The information carried by drought-resistance index from shrubs on top of mountain is basically in consistence with it on bottom of mountain. It was considered that the information in first principal and second principal components of Reaumuria soongorica were water condition indices ,rotective enzymes and osmoregulation matters. the information in first principal and second principal components of caragana korshinkii were water condition and the indices about the stability of plasmalemma, and the third principal components were protective enzymes and osmoregulation matters; the information in first principal and second components of nitraria sibirica were protective enzymes,osmoregulation matters and the indices about the stability of plasmalemma,and the third principal components were Chlorophyll.By analyzing comprehensive appraisal of all physiological and biochemical indices, the results showed that the ability of drought resistance of three species were Reaumuria soongorica>caragana korshinkii>nitraria sibirica.Drought-resistance of shrubs at top of mountain was better than bottom in north mountain of lanzhou.