The Study Of The Effects Of Iron Tailings Matrix Improvement On Plant Photosynthetic Physiological Characteristic And Growth

This study was conducted in the botanical garden from the west campus of Agricultural University of Hebei, and local native species Castanea mollissima, Juglans regia, Robinia pseudoacacia and Amorpha fruticosa were adopted as the experiment objects. By improving the soil matrix and observing the effect of different tailings matrix methods on the growth of the plants, we can explore the method matrix modified of mining wasteland and the mode of vegetation restoration which is low cost, easy to operate and good effect. This study had carried out many improvements methods on matrix of iron tailings in order to observe the impacts different substrate-improved methods of iron tailings on growth of economic tree species of Castanea mollissima and Juglans regia, and to determine the best substrates on the growth of economic tree species improvement in two ways, ultimately, ecological and economic benefits bumper ends. Li-6400 portable photosynthetic system was used in this study to accomplish the determination of the diurnal changes of photosynthesis, transpiration and water use efficiency from 7:00 to 17:00, in order to determine the effects of different treatments for the growth of two species. In order to disscuss effects of different iron tailings matrix improving methods on photosynthetic physiological characteristics of Robinia pseudoacacia and Amorpha fruticosa, the studies on diurnal change of photosynthetic characteristics of Robinia pseudoacacia and Amorpha fruticosa were also conducted, in order to find the best mode of abandoned mines’soil and vegetation restoration, and provide experimental basis for the further mining wasteland restoration. The results showed as followings:(1) The growth of Castanea mollissima in the sand of iron tailing is the best, and Juglans regia grown under half- sand and twice-times fertilizer is best.(2)The diurnal change of net photosynthetic rate(Pn) of Robinia pseudoacacia and Amorpha fruticosa mostly presented single-peak curves, the peak value occurred at 9:00-10:00. Only the sand matrix of Robinia pseudoacacia shows a double-peak curve, the first peak value occurred at 10:00 and the second one at 15:00, with midday depression of photosynthesis.(3)The diurnal course of stomatal conductance of Robinia pseudoacacia and Amorpha fruticosa exhibited also a similar diurnal course of photosynthetic rate and transpiration rate(Tr) simutaneously, and shown that Pn play instructions regulatory role on Gs.(4)The diurnal change of water use efficiency(WUE) in different matrix of Robinia pseudoacacia mostly presented double -peak curves, but Amorpha fruticosa all presented singel-peak curves.(5) All kinds of photosynthetic physiological parameters of two tree species in different matrix had no obvious difference, so we can implement vegetation restoration on half soil matrix even the whole sand matrix. From the economic point of view, in mining wasteland vegetation recovery, fertilization is unnecessary.(6)The experiment proved that the best method is to half mixed with soil and rational fertilizing, as well, making sure to have enough sunlight. Considering the costs, Robinia pseudoacacia and Amorpha fruticosa can directly be planted in the mine tailings,to achieve the retention of soil fertility.