Influence of Nitrogen Fertilization on the Growth and Yield of North American Ginseng

ABSTRACT

Information on nitrogen (N) fertilization of North American ginseng (Panax quinquefolius L.) is needed to optimize dry matter accumulation, ginsenoside concentration, and root yields. Field experiments were initiated in 1995 and 1996 to study the effects of N fertilization on dry matter accumulation, N concentration and accumulation, final root yield, and ginsenoside concentration of American ginseng production in a Fox loamy sand (Psammentic Hapludalf). Ammonium sulfate was broadcast-applied at rates of 0, 10, 20, 30, 40, 50, 60, and 70 kg N/ha prior to seedling emergence in the spring of each of the four growing seasons. The eight N treatments were arranged in a randomized complete block design with four replications. Ginseng plant dry weight showed a quadratic response to increasing N rate. As the rate of N fertilizer applied was increased, significant increases in tissue N concentration resulted. Approximately, 50 percent of the total N accumulated was allocated to the roots in the first year of growth while approximately 66 percent of the total N accumulated was allocated to the roots in the subsequent years of growth. Ginsenoside contents of the harvested roots were not significantly affected by N fertilizer application rates. Based on the quadratic model fitted to the data, maximum yields of four-year-old commercially harvested ginseng roots can be obtained in Ontario with annual additions of about 40 kg N/ha in the spring, prior to plant emergence.

KEYWORDS:

• Dry matter accumulation
• N accumulation
• N concentration