| Acid rain is one of serious environmental problems in the world. However, its dangers and pollution mechanisms haven't been completely understood yet, because of the complexity of the influences of acid rain on eco-system. Casuarina shelter forests are very important to breaking wind and fixing sand in China's southeastern seashore. They play a remarkable role in improving the ecological environment and promoting the economic development. Obtained the highly purified plasma membrane vesicles from Casuarina equisetifolia seedlings cultivated under artificial acid rain stress as experiment materials, which isolated by aqueous two-phase partitioning methods, the study first focused on the responses of plasma membrane transport system activities to acid rain stress or the double stresses of acid rain and NaCl, to study the harm to Casuarina equisetifolia done by those stresses and the chemical regulation of the impair, and to probe into the mechanism of receiving and transferring the stress signals. The study also analysed the effects of acid rain to the organic solutes and trace elements metabolize in Casuarin equisetifolia -soil system. The mainly results of the study are as following:There were some effects of acid rain on the growth of casuarina equisetifolia seedlings based on pot experiments. In comparison with control, there isn't significant change of the apparent growth of above ground seedling and fresh weight of the seedling, but the elongation of root system and the dry matter accumulation of the individual seedling were obviously reduced, and the levels of producing nodule also markedly fell under the acid rain stress with a series of acidity (pH4.5~2.5) for 3 months.The plasma membrane H-ATPase and Ca2 + -ATPase of Casuarina equisetifolia seedling were both sensitive to acid rain, and the inhibition of their activities were more and more strongly with the acidity increase of acid rain generally. pH4.5~2.5 acid rain led to the reduce of PM KT-ATPase activities to 76.64%~85.88% and made the PM Ca2+-ATPase activities 14.12%~4.7% of CK. But pH3.0 acid rain enhanced H^-ATPase and Ca2+-ATPase activities 175.32%and 91.28% separately. The rebound was probably due to a kind of physiological stimulated respond to resist stress of the Casuarina equisetifolia seedlings when the intension of acid rain stress accumulation to a certainty in the system of Casuarina equisetifolia and pot soil after period of time.Acid rain brought obvious effects on the plasma membrane redox system of potted Casuarina equisetifolia seedling. The activities of NADH oxidase,Fe(CN)^ reductase, EDTA -Fe3+ reductase, and nitrate reductase have similarresponses to pH4.5~2.5 acid rain. In generally, with the acidity of acid rain increased, it showed the activities decreased at first, then with the accumulation of acid rain stress intension, the activities were stimulated to rebound higher than CK, while the activities decreased severely under the acid rain stress with high acidity. The peak values of the plasma membrane redox enzymes activities all appeared at pHS.O acid rain treatment, and the lowest values all represented at pH2.5 acid rain treatment except for nitrate reductase (the lowest value of nitrate reductase activities represented at pH4.5 acid rain treatment). The results also showed that the feedback actions with stimulation of the plasma membrane redox enzymes to acid rain are earlier than those responses of plasma membrane ion pumping to acid rain.The PM H^-ATPase and Ca2 + -ATPase activities of Casuarina equisetifolia seedling under the double stresses of pH4.5 acid rain and NaCl(2~8g/kg soil) were both higher than those under the single stress of pH4.5 acid rain, which indicated the double stresses of acid rain with low acidity and NaCl might partly alleviate the single acid rain stress on the physiological process of Casuarina equisetifolia. While acid rain stress with high acidity(pH3.0) might cooperate with the NaCl stress, which brought severe effects on PM H*-ATPase and Ca2+-ATPase activities of...
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