Abiotic Factors Influencing Growth and Ginsenoside Content of Panax ginseng Roots

Abstract

We aimed to evaluate the effects of abiotic factors on root growth and ginsenoside content of Panax ginseng and on the tradeoff between these two properties. Three experiments tested the effects of fertilization, soil particle size and cultivation site, respectively, on root growth and ginsenoside content. Moderate applications of nitrogen, phosphorus, and potassium did not significantly influence ginsenoside content. Root weight was negatively correlated with ginsenosides Rg1 and Rg2 with excessive fertilization, suggesting that environmental stress caused by excessive fertilization might have created a tradeoff. We tested the effect of soil type by separating soil out according to particle size (ie, < 0.5, 0.5-1 and 1-2 mm, and a mixed control). Root weight was lower in soil of < 0.5 mm, and roots were longer in soil of 1-2 mm compared with those of the control. Total ginsenoside and ginsenoside Rb1 content was lower in soil of < 0.5 mm than those of the unsieved control. These results indicate that soil texture is an important factor determining ginsenoside yield and root quality. The effect of cultivation site was compared among 5 locations using the same soil type. There was a 2.8-fold difference in root weight and a 2.1-fold difference in total ginsenoside content between the highest and lowest values among 5 sites, and no significant correlation was found between root growth and ginsenoside content. Our results suggest that ginsenoside content was influenced by abiotic stresses caused by changes in nutrient, moisture, and temperature. We conclude that proper management of abiotic stresses can promote both root growth and ginsenoside content without a tradeoff between these two properties.