Effects of Zinc Concentration on Growth, Ginsenoside Content and Zinc Content of Panax ginseng by Foliar Application

In order to identify appropriate Zn concentration range of foliar spraying for ginseng, effects of zinc spraying concentration on growth, ginsenoside content and zinc absorption efficiency by leaves of ginseng were studied through field experiments. Results showed that ginseng leaves can efficiently uptake Zn²⁺ of foliar applied, and transformation of Zn from leaves to roots was found. The amount of Zn uptake by leaves had significant (P<0.01,R ²>0.9) positive correlation with applied Zn mass concentration range from 20-20 000 mg/L. As spraying concentration increased, the amount of zinc transferred from leaves to roots was also enhanced. Increment of fresh mass and ginsenoside content of root were found when appropriate Zn nutrient solution(200 and 2 000 mg/L) was applied, and peroxidases (POD) and catalase (CAT) activities increased when applied rate was 200 mg/L, but spraying 2 000 mg/L Zn²⁺ led to POD activity increase and CAT activity decrease compared to control. Although malondialdehyde（MDA）content increased, CAT activity decrease and leaf burn were observed when 2 000 mg/L was supplied to ginseng leaves, and ginsenoside significantly increased in root. This may be due to of environmental pressure induced by secondary metabolite accumulation. Appropriate Zn mass concentrations of foliar application in ginseng ranged from 200-2 000 mg/L.