| Using woody plants for ecological restoration and reconstruction for southern heavy metal slag wasteland which are mainly hills and mountains is an important method. Studying on heavy metal stress on the photosynthetic characteristics of some species, and revealing their adaptive mechanisms, it is of great significance to choosing the correct species for restoration of the slag wasteland,controlling heavy metal pollution of the soil and ecological restoration. By using the slag wasteland soil in Xiangtan Manganese Mine, five different mixed soil treatments by which potted plant tests are conducted, five treatments are as follows:(CK:100% untreated soil; Wl:25% slag wasteland soil+75% untreated soil; W2:50% slag wasteland soil+50% untreated soil; W3:75% slag wasteland soil+25% untreated soil; W4:100% slag wasteland soil). This paper focuses on the impacts of heavy metal polluted soil in slag wastelands of manganese mine on photosynthetic physiological reactions,relevances among Pn and all factors,and inhibits on the growth by comparative study of Koelreuteria paniculata Laxm and Elaeocarpus decipens which have many promising uses so as to reveal physiological and ecological responses of the overground part of the two species. The results showed that:1. The diural net photosynthetic rate of W1,W2 and W4 treatments of Koelreuteria paniculata Laxm in July varies with double peak curves, while the diural net photosynthetic rate of the contrast(CK) and W3 varies with single peak curve. The diural net photosynthetic rate of Elaeocarpus decipens (except W4 treatment) varies with double peak curves. The daily average net photosynthetic rate (Pn) of Elaeocarpus decipens is higher than that of Koelreuteria paniculata Laxm in July. For Koelreuteria paniculata Laxm, the daily average net photosynthetic rate (Pn) of each treatment (W1,W2,W3,W4) is 66%,87%,106%,117% compared to the contrast and increases with the concentration of heavy metals in the soil. While for Elaeocarpus decipens, the daily average rates of (Pn) are 73%,83%,72.7%,57% compared to the contrast and raises when the soil heavy metal concentration increases, and then decreases. Impacts of soil heavy metal concentrations on Koelreuteria paniculata Laxm are relatively smaller than that of Elaeocarpus decipens. Heavy metal treatments make the range of diural variation of (Gs) and (Tr) decrease of both two species. For Koelreuteria paniculata Laxm, Wl and W4 treatments make the range of diural variation of (Ci) increase, while W2 and W3 treatments make it decrease. For Elaeocarpus decipens, W1,W2 and W4 treatments make the range of diural variation of (Ci) increase, while W3 make it decrease.2. Focused on net photosynthetic rate (Pn) of the two species in Summer and Autumn, the results showed that the average net photosynthetic rate (Pn) of both two species in Summer are higher than in Fall, and the relationship among all treatments (W1,W2,W3,W4) of the average net photosynthetic rate (Pn) has changed in Autumn. For Koelreuteria paniculata Laxm in Summer, the average value of Pn of W3 is the largest, that is 4.74μmol·m-2·s-1, only the value of Pn of W3 is bigger than the contrast, W1 is the minimum, that is 2.36μmol·m-2·s-1, While in Autumn, the average value of Pn of W2 is the largest which is 2.56μmol·m-2·s-1, W3 is the minimum which is 2.12μmol·m-2·s-1, the value of Pn of all treatments are higher than the contrast which is1.72μmol·m-2·s-1. For Elaeocarpus decipens in Summer, the average value of Pn of W2 is the maximum, that is 4.52μmol·m-2·s-1, while W4 is the minimum, that is 3.59μmol·m-2·s-1, the value of Pn of all treatments are lower than the contrast which is 6.04μmol·m-2·s-1; In Autumn, the average value of Pn of W1 is the largest which is 2.36μmol·m-2·s-1, while W4 is the minimum which is 1.73μmol·m-2·s-1, the value of Pn of all treatments are lower than the contrast which is3.05μmol·m-2·s-1.3. For Koelreuteria paniculata Laxm relevances among Pn and heavy metals Mn,Cu,Zn,Pb,Ni,Co,Cd contents in soil all fail to meet the significant level; while relevances among Pn and Pb,Cd and Cu contents in soil reach negative significant level of Elaeocarpus decipens. Relevances among Pn and N,Chlorophyll contents in leaves reach significant negative level, while Pn among Zn and Mn contents in leaves of Koelreuteria paniculata Laxm reach positive significant level; For Elaeocarpus decipens, Relevances Pn among N,P,K,Mg,Ca,Fe,Mn,Zn and Chlorophyll contents in leaves all fail to meet the significant level.4. Survival rate and height growth rate of Koelreuteria paniculata Laxm are lower than those of Elaeocarpus decipens. height growth rate of Koelreuteria paniculata Laxm each treatment (exceptW3) is higher than that in fall; the average diameter growth in order is W3>W4>CK>W2>W1, W1 and W2 are less than the contrast, while W3 and W4 are larger than the contrast. It means that low concentration inhibits diameter growth, while high concentration promotes it.Elaeocarpus decipens grow fast and grow well, height growth rate in summer is far more higher than that in autumn. The average diameter growth in order is CK> W2> W1> W3> W4, all treatments are lower than the contrast, heavy metal treatments in the soil inhibits diameter growth, and with the increase in the concentration of heavy metal, the inhibitory effect gets more obvious.5. Among all the heavy metals, content of Mn losses the most. Compared with its in the early stage of experiment, for both of the two species, W2 lost the most Mn content, W1 lost the least, at the end stage of the experiment, Mn content in the soil of each treatment of Koelreuteria paniculata Laxm in order is 62.9%,21.34%, 50.33%,43.38% of its early stage; For Elaeocarpus decipens, Mn content in the soil of each treatment in order is 63.45%,21.1%,41.2%,41.66% of its early stage. The causes of so much loss in Mn content are mainly due to rainfall,irrigation and absorption of the plants. Elaeocarpus decipens has better capacity to absorb Mn and Pb elements than Koelreuteria paniculata Laxm, while Koelreuteria paniculata Laxm absorbs more Cu and Zn elements than Elaeocarpus decipens.
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