Stress Tolerance Of Koelreuteria Paniculata To Polluted Soils Of Manganese Mining Wasteland

Owing to abandoned mining, a series of biological environmental problems such as the wrecked sighting, the terrible pollution of heavy metals, the deteriorated water quality of groundwater and Lower Reaches, the fearful decrease of biological diversity and so on, has become an important factor to affect the development of the regional economy. Thus, ecological restoration of abandoned mining region has been an urgent task in China. A large research is shown that some plant can grow well in the abandoned mining with plenty of heavy metals. By the tracing experiment of Koelreuteria paniculata planting in the different treatment six soil in one year:tail mine, tail mine mud, semi-tail mine and semi-soil, semi-tail mud and semi-soil, soils of admixture from tail mine and tail mine mud, contrasting soil, the adaptation strategy of root in morphology and behavior in polluted soils by heavy metals is attempted to find, and meanwhile the accumulation and transferability of heavy metals in plants are also sated. Therefore, scientific basis is supplied for revealing the mechanism of adaptation and mitigated contamination by heavy metalsBased on the experiments, the main conclusions are as follows:the early of late order of germinator of Koelreuteria paniculata under different kinds of soils is:tail mine, semi-tail mine and semi-soil, the contrasting soil, semi-tail mud and semi-soil, tail mine mud. The content of chlorophyll of the Koelreuteria paniculata leave is related to the content of heavy metals. The result from the testing results of above various soils is shown that the higher content of the heavy metals in the soil leads to the lower content of the chlorophyll.Lateral root branch, root hairs of the Koelreuteria paniculata in the contrasting soil are lower than those in the tail mine and are higher than those in the tail mine mud. Lateral root radius of the Koelreuteria paniculata in the contrasting soil are higher than those in the tail mine. The biomass, the above ground biomass, the underground biomass, the biomass of lateral root, the number and the length of the first lateral root, the number of the fine root, the total length of root of the Koelreuteria paniculata in the tail mine and in the semi-tail and semi-soil are higher than those in the contrasting soil:While, those in the semi-mud and semi-soil are lower than in the contrasting soil, which, of course, are much lower than in the tail mine and in the semi-tail and semi-soil. The biomass, the above ground biomass, the underground biomass, the biomass of lateral root, the number and the length of the first lateral root, the number of the fine root, the total length of root of the Koelreuteria paniculata in the semi-soil and semi-mud basically keep in the original stage or slight increase with the adding time. That is to say the Koelreuteria paniculata could accommodate to live in the tail mine but in the tail mud, which makes it dead.The concentration of the heavy metals, Mn, Zn, Fe in the lateral root of the Koelreuteria paniculata is evidently higher than in the stump, in the leave, and in the stem, where the content of heavy metals is lowest, in all of the tested soils but the Mn the concentration of which in the lateral root is less than in the leave.According to the three conditions of the hyperaccumulator:firstly, the content of heavy metals of the above ground(including the stem and the leave) of the vegetable should reach the critical standard(10000mg/kg); secondly, the ratios of the EC(the content of heavy metals of the above ground of the vegetable compared to that in the soil) and TF(the content of heavy metals of the above ground of the vegetable compared'to that in the root) are both more than 1; moreover, the vegetable should grow well and be not distinctly damaged even if it could meet the above two conditions, the Koelreuteria paniculata belongs to the patient vegetable of the heavy metals, Mn, Zn, Fe, but the hyperaccumulator because for one thing, the highest content of heavy metals, Mn, Zn, Fe of the above ground of the Koelreuteria paniculata could not reach the critical standard; for another, their EC and TF are simultaneously less than 1 or could not be more than 1 at the same time.In the mining polluted soils, the branches of root increase as well as the number of the fine root does, too; the period of transformation of the fine root is fast. The phenomena that the most Mn enrich in the lateral root and only few Mn transfer to the stem and the leave is a kind of accommodation to the contaminated soil by the heavy metals.