Effects Of Fe²⁺ And Mn²⁺ Stress On The Growth Of Panax Quinquefolium L.

Iron and Manganese are essential elements for plant growth and development, and play animportant role in the physiological metabolism process. But if they are excessive the growth of theplants will be influeced. In this study, the2-year-old American ginseng as the test material, five Fe²⁺andMn²⁺concentrations are installed to study the effects of the growth of American ginseng by Fe²⁺andMn²⁺stress. The main results are as follows:1. The physiological metabolism of American ginseng was directly affected by Fe²⁺and Mn²⁺stress.Fe²⁺stress reduced the contents of chlorophyll a, chlorophyll b and carotenoids of American ginsengand their contents showed a high correlation with the level of Fe²⁺supplying and the correlationcoefficients were0.966,0.9732and0.9547. Respectively, the chlorophyll a, chlorophyll b andcarotenoids content of Mn processing concentration showed a trend of decreasing at first and increasingthen. The chloroplast pigment reached a low level at Mn3treatment. The carotenoids contents showed ahigh correlation with the level of Mn²⁺supplying, and the correlation coefficient was0.9462. Theactivity of POD increased under the Fe²⁺stress. The activity of CAT increased at first and decreasedthen under the Fe²⁺stress. The activity of POD and CAT increased at first and decreased then under theMn²⁺stress. The activity of POD showed a high correlation with the level of Fe²⁺and Mn²⁺supplying,and the correlation coefficients were0.9156and0.9802. Respectively, the contents of proline increasedat first and decreased then under the Fe²⁺stress. The contents of proline increased under the Mn²⁺stress.The contents of proline showed a high correlation with the level of Mn²⁺supplying, and the correlationcoefficient was0.9844. The contents of MDA increased at first and decreased then under the Fe²⁺stress.Mn²⁺stress increased the contents of MDA. The contents of MDA have a good correlation with thelevel of Fe²⁺supplying, and the correlation coefficient was0.9121.2. Fe²⁺and Mn²⁺stress resulted in the disorders of mineral metabolism of American ginseng.Fe²⁺and Mn²⁺stress influenced the absorption and distribution of Mn, Fe, Cu and Zn. Theyresulted in the deficience of nutriens or the lost of balance of the essential elements and disrupted thenormal physiological metabolism. Finally the growth of the American ginseng will be influenced. In theFe4processing, the Fe and Zn contents of the aerial parts, the Mn, Cu and Zn contents of the roots areminimum, lower than the control38.18%,16.41%,27.87%,23.18%and8.80%. While the Fe content ofthe roots, the Cu content of the aerial parts are higher than the control31.93%and344.98%. In the Mn4processing, the Mn content of the roots, the Cu content of the roots are higher than the control88.92%and168.19%; while the Fe, Cu and Zn contents of the roots, the Zn content of the aerial parts areminimum, lower than the control33.04%,41.17%,27.08%and59.80%.3. The contents of ginsenosides of American ginseng were affected by Fe²⁺and Mn²⁺stress.Fe²⁺and Mn²⁺stress affected the contents of monomer saponin at different degrees and reduce thetotal saponins. The contents of total saponins decreased with the increasing of Fe²⁺and Mn²⁺concentrations. The content of the control32.021mg/kg, the highest, the content of Fe4and Mn4 processing were26.579mg/kg and27.502mg/kg, lower than the control17.00%and18.77%, and thetreatment groops are significantly different with the control group （P<0.05）.4. Fe²⁺and Mn²⁺stress have a certain effect on the leaves and roots of American ginseng.Fe²⁺stress significantly damaged the leaves, the roots and the microstructure of Ameican ginseng.The extent of damage increased with the increasing of the Fe²⁺concentration. The leaves of Americanginseng were damaged by Mn²⁺stress. The growth of the roots were promoted at low Mn concentration,but were inhibited at high concentration.Fe²⁺and Mn²⁺stress affect the vivo metabolism of American ginseng. The synthesis of thephotosynthetic pigment was affected. The antioxidant enzyme systems and the penetration regulatingsubstances would mitigate the effects of the stress causing. Fe²⁺and Mn²⁺stress eventually lead to thedamage of the leaves and the root and the metabolic disorders of the mineral elements, and thus thesaponins synthesis would be affected.