Effect of nitrogen, phosphorus and potassium deficiency on content of phenolic compounds in exudation of American ginseng

Abstract

Some of the phenolic compounds detected in the soil of commercially cultivated American ginseng could inhibit the seed germination and seedling growth of American ginseng. In this paper we studied the root exudation of American ginseng induced by deficiency of nitrogen, phosphorus and potassium on the content of phenolic compounds. Two years old American ginsengs were cultured in hydroponic culture with different nutrient solution. The culture solution was collected after 14 days. The exudations of different polarities in the culture solution were enriched by the amberlite XAD4 and XAD7. The content of the total phenolic acids in the exudation was analyzed by Folin-Ciocalteu colorimetry; the contents of vanillic acid, p-coumaric acid and trans-cinnamic acid were detected and quantified by HPLC. Both in the situation of nitrogen and potassium deficiency, the concentration of total phenolic compounds increased significantly in the exudation of American ginseng comparing with the complete nutrient solution (P < 0.05) , while decreased significantly under phosphorus deficient conditions (P < 0.05). The contents of the 3 autotoxic phenolic acids decreased significantly under nitrogen, phosphorus and potassium deficient conditions (P < 0.05). The contents of total phenolic compounds and the 3 autotoxic phenolics in the root exudation of American ginseng altered variously in the deficiency of nitrogen, phosphorus and potassium.