| According to the contaminated situation of plantation around a electric zinc factory in southwest China, three representative contaminated sample area and unpolluted sample area (0) were selected around this factory (1,2,3), and soil was collected from these sample area, determining its physical and chemical properties, and main content of Cu, Zn, Pb, As. In addition, pot experiment was adopted to discuss three different level of soil heavy metal pollution (including the original soil planting1,2,3, recorded as Ti, T2and T3, respectively), and the original soil and unpolluted soil were diluted by1:1(recorded as T1+0, T3and T2+0, respectively) and then used to plant alder (Alnus cremastogyne) and pepper (Capsicum annuum). Morphological characteristics, photosynthetic physiological characteristics and the resistance physiological characteristics of these three plants were analysed. The results are as follows:(1)1,2, and3soil were detected having significantly higher content of Cu contentof Cu, Zn, Pb and As than0soil, and Cu, Pb and Zn were the main heavy metal pollutants, especially in3. The content of heavy metals Cu, Zn and Pb were as81times,91times and25times as that of the CK, respectively. The soil pH under different level of heavy metal pollution were significantly lower than0(P<0.05). The total nitrogen, total phosphorus content of1,2and3soil were significantly higher than0(P<0.05), and soil total potassium content was lower than0(P<0.05), but their variation had no significant effect on plant growth.(2)1,2soil had strong inhibitory effect on the growth of the alder. The alder sapling could not survive in the soil. Hot pepper seeds were difficult to germinate in these three kinds of contaminated soil. The inhibition of diluted original polluted soil and unpolluted soil in a ratio of1:1for pot experiment on plant growth were obvious, but its effect was weaker than the undiluted contaminated soil.(3) the treatment of T1+0and T2+0could inhibit the pigment synthesis of chili and alder, while the treatment of T3+o would interfere with the normal pigment decomposition or transformation of them to make its content increase significantly. From the plant photosynthetic parameters, the net photosynthetic rate of alder will be significantly reduced along with the degree of soil pollution (P<0.05), and when the stomatal conductance decreases along with the degree of soil pollution, the intercellular CO2concentration will ascend along with the degree of soil pollution, which illustrates the decline of photosynthetic rate of alder is caused by non-stomatal limitation factors. By the way, the photosynthetic rate of pepper is not significantly affected.(4) SOD and CAT activity of alder increased with the increasing concentration of heavy metal, the T2+0and T1+o could remove excessive reactive oxygen species, making MDA content had no significant change. However, in the T3+0, SOD and CAT could not remove excess reactive oxygen species timely and effectively, thus the MDA content significantly increased; The activity of POD was still significantly lower than CK (P<0.05). But SOD activity of pepper under T2+0and T1+o had no significant difference with CK (P>0.05). SOD and CAT activity of T3+o were significantly lower than CK (P<0.05), while POD activity rose with the increasing concentration of heavy metal and then declined, the MDA content of hot pepper did not increase under different treatments.(5) In T1+0, alder increased its soluble protein to regulate osmotic potential, but under T3and T2+0its content decreased significantly (P<0.05), and its soluble sugar content and proline content showed a decreasing trend with the degraded degree of heavy metal pollution. Under T2and T1+o, soluble protein, soluble sugar and proline content of pepper were not significant difference with CK (P>0.05), but soluble sugar and proline content of T3+0were significantly lower than CK (P<0.05), and there was no significant difference of soluble protein between T3+0and the CK (P>0.05).Overall, the growth of the alder was inhibited significantly by the contaminated soil that around the electric zinc factory. It had a serious impact on the physiological characteristics of alder and the growth of pepper. However, there is no obvious influence on pepper physiological characteristics. |
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