| With the social and economic development, more and more mineral resources were exploited, which caused severe pollutions and many other problems: natural ecological systems were destroyed, lots of land were wasted and heavy metals, such as Cu,Pb,Zn and As, came into soil to produce serious pollution, and so on. Ecological reclamation of mineral wasteland have been one of the urgent tasks we are facing nowadays. Kinds of the reclamation methods of pollution soil have been tested worldwide so far. However, compared with physical and chemical ways of reclamation, biological and ecological reclamation is a prior one due to its lower cost, effectual outcome and no secondary pollution. The key step for the ecological reclamation is the selection of heavy metal-resistant plants. To do so, we first need to study effects of heavy metal on plants and the reactions and resistant mechanism of the plants.Based on investigations of the copper tail mining wasteland and vegetation condition in Wugongli, Tongling, we found that a grass Trifolium repens was a Cu resistant plant species, which was also a dominant species in community. The effects of Cu,Cd in single or combined pollution on the growth and activate oxygen metabolism of T. repens seedling were studied with water cultivated and pot experiments. We also studied the correlation of toxic effects of Cu and four kinds of soil enzymatic activities, trying to found indicating enzymes of heavy-metal-pollution in soil. Results were as follows:1. There existed totally 49 species of settling plants, which belong to 46 genuses in 22 families. The vegetation primarily composed of annual or biannual and perennial herbs, which formed 4 types of relatively-stable communities. The dominant species in communities were T. repens, Cynodon dactylon, Imperata cylindrical, Medicago lupulina, Conyza Canadensis, Erigeron annuus,etc.2. Hoagland cultivation experiments showed that the growth of T. repens seedling could be improved by low concentration of Cu(<10mg·L-1).Also,the fresh/dry weight, content of soluble protein, number and height of fibrous roots and the above-ground height of the seedling were slightly increased. Moreover, SOD,CAT and POD activities increased slightly in the activate oxygen metabolism system of seedling, and the balance of protective enzyme system was hold. However, with the increase of concentration of Cu(10~100mg·L-1), the seedling grew slowly and the content of leaf pigments decreased. The activate oxygen metabolism system was destroyed and its balance was broken. Activities of SOD and CAT decreased respectively by 26.67% and 71.31%, while POD activity increased 10.6 times. Furthermore, the increasing of MDA content under high concentration of Cu induced the membrane penetration and electric conductivity of leaf cells to rise greatly. It would produce disorder in physiological metabolism of seedling, and speed up their senility and death.3 It was showed in pot experiments that the growth of T. repens seedling was improved by low concentration of Cu(<500mg·kg-1). The fresh/dry weight, content of soluble protein, the above-ground height of the seedling, SOD,CAT and POD activities in the activate oxygen metabolism system of seedling also increased slightly. And the balance of protective enzyme system was still hold. However, with the increase of concentration of Cu(500~3000mg·kg-1),the seedling grew slowly, the biomass and content of leaf pigments decreased drastically. The activate oxygen metabolism system was destroyed and its balance was broken, and activities of SOD and CAT decreased respectively by 33.4% and 37.7%,while POD activity increased 3.4 times. Furthermore, the increasing of MDA content induced the membrane penetration and electric conductivity of leaf cells to rise, which would produce disorder in physiological metabolism of seedling and speed up their senility and death.4 It was found that in the pot experiments of Cu/Cd pollution in single or combined:(1) The growth of seedling could be restrained, and the leaf grew yellow and co...
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