| The ginseng planted in farmland which brought the risk of heavy metal pollution. At the same time it increased the risk of lead pollution to ginseng. So we need to do the prevention research in advance to discuss some effects of ginseng which accumulated lead. This study selected two-year-old healthy ginseng seedlings as raw materials. The way of soil culture imitated natural growth environment. According to the soil environmental quality standard, the contents of Pb were set up at five processing levels, in order to explore more effects on ginseng growth and metabolism under different concentrations of Pb stress. This study could provide scientific evidence for the influence of the quality and safety of ginseng under Pb stress. We should raise our vigilance to the serious environmental pollution of the hazards of safety of ginseng as food or drug. This research mainly had the following findings:1 The effects of ginseng growth and physiological characteristics under lead stress. The change of the relative growth rate is the integrated embodiment of ginseng to Pb stress. In this experiment the relative growth rate of ginseng appeared reducing gradually with the increase of Pb stress. Through the regression analysis, the relationship between the relative growth rate of ginseng and Pb concentrations was becoming significantly negative linear correlation(P<0.05,y =-15.27 x + 71.084). In the leaf-expansion period the SPAD of ginseng leaf had increased while Pb concentration was higher than 500 mg/kg. Then in the green fruit period, red fruit period and mature period, the SPAD of ginseng leaf decreased under Pb stress which means that the chlorophyll content decreased.With the increase of Pb content, the activity of SOD of ginseng root, stem and leaf in different periods increased firstly and then reduced. At the same time and same level under Pb stress, the content of the SOD of ginseng root, stem and leaf were compared as follows: leaf>stem>root, which showed the ability of removing superoxide anion compared as leaf>root>stem. The activity of POD of ginseng increased with Pb content to enhance leaves in fall. The activity of POD of ginseng root in different periods was higher than the other two parts, and it was also found that in the green fruit period the POD of ginseng leaf was always higher than the other two periods. The CAT activity of different parts of ginseng under Pb stress increased at different levels, the CAT activity of ginseng root in different periods reached the highest when the content of Pb2+ was 250 mg/kg. The CAT activity of ginseng stems increased with the increase of concentration of Pb firstly and then decreased, peaked at 250 mg/kg. The variations of the CAT activity of ginseng leaves were little through these findings. In each growth period under the same Pb stress, the MDA content of ginseng in different organs compared as: leaf > stem > root. From the influence of MDA content of ginseng each organ under different Pb contents, the MDA content of ginseng in different growth periods were rising.2 The influence of ginseng flower organ under lead stressThe control of ginseng pollen vitality was 44.08%. By linear regression analysis, ginseng between the pollen vitality and Pb concentrations was significantly negative linear correlation(P<0.05,y =-0.045 x + 0.432). Under Pb stress of pollen surface condition and its dynamic relationship was unclear, but compared with the normal growth under the condition of pollen morphology, the surface condition was bad for pollination and fertilization. Ginseng crabapple period between fruit-bearing rate and concentration of Pb added was significantly negative linear correlation(P<0.05,y =-7.727x+51.023).3 lead stress effects on ginseng medicinal ingredientsFrom the perspective of the content of ginseng total saponins, as with the increase of Pb concentration, the trend of total ginsenosides was increasing. Pb2+ concentration of 100 and 250 mg/kg treatment on the influence of ginseng total saponin content was not significant, but at 500 and 1 000 mg/kg content the total amount of ginseng saponin was significantly increased, increased 33.2% and 35.9% respectively than the control, but it is not significant different between the two ones. The relationship between lead concentrations and ginseng total saponin content was significant linear correlation(P<0. 05,y=1.78x+18.62). Soluble total sugar of ginseng roots ranged from 10.19% to 12.59% of their weight. When the concentration of Pb2+ was at 100 mg/kg, there was no significant impact on ginseng total sugar content. With the increase of concentration of lead processing, ginseng total sugar content increased. When the concentration was at 1000 mg/kg, ginseng root soluble total sugar made up 12.59% of ginseng’s total weigh. By linear regression analysis, the lead concentrations and ginseng total sugar content of present was significant positive linear correlation( P<0. 01,y=6.059x-11.944). |
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