2019 ASHS Annual Conference

Ginseng production in Korea involves three cultural phases: seed germination and seedling culture during the first year, transplanting of the one-year old seedlings to well-prepared soil beds that are amended for desirable fertility and physical property, and culture of the plants under shade for 4-6 years until harvest. While seedlings were raised on mineral soils under shade outdoors, there is an increasing trend now of producing seedlings in amended root substrates in raised beds in the greenhouse. Precise control of fertility for root substrates is essential for raising healthy seedlings especially when inert media with low buffering capacity are used. Reports in this area of research for ginseng is largely lacking. The objective of this study was to investigate the influence of fertility (as measured by EC) of the nutrient solution used for seedling production. The raised beds of 120 x 60 x 25 cm (length x width x height) were filled with root substrate composed of peat moss + perlite (7:3, v/v) and cold-stratified seeds were sown on Mar 9, 2018 (300 seeds per treatment, 3 cm x 3 cm spacing). After seed germination, fertigation of the beds started on May 21 using each of six nutrient solutions containing 0.4, 0.6, 0.8, 1.0, 1.2 dS·m^-1 EC prepared with ground water (0.25 dS·m^-1) and fertilizer stock solutions. The pH of all solutions was adjusted to 5.8±0.5 and the stock solution contained (mM): 2 NH₄⁺-N, 12 NO₃^--N, 1 H₂ PO₄^-, 8 K⁺, 2 Ca²⁺, 1 Mg²⁺, 1 SO₄^2-. Fertigation frequencies were controlled using the GS-3 soil moisture sensor and treatment solutions were automatically supplied 30 minutes when volumetric water content decreased to 36% (amounts of supplied solution per treatment were 0.4-0.45 L and 20-30% of supplied solutions were drained). The measurements of plant growth and tissue and soil analyses were made twice: first on July 31 and 2^nd on Sept 21. For the first growth measurement, elevating EC in fertilizer solution resulted in enhanced growth, but statistical differences among treatment solutions, except ground water (EC 0.25), were not significant. In the second measurement, the seedling growths in terms of dry weight of above- and below-ground plant parts increased significantly when solution ECs were elevated up to 1.0 dS·m^-1 but decreased again at 1.2 dS·m^-1 treatment. In both the 1^st and 2^nd measurements, the mineral tissue nutrient contents of T-N, P, K and Ca were different significantly among treatments, while tissue contents of other elements were unaffected by treatments. The T-N and P contents of roots were higher than those of the above-ground plant parts, but the Ca content of the above-ground tissue were 11 to 14 times higher than those of the root tissues. The EC of root media in the 1.0 dS·m^-1 treatment, in which the seedling growths were the highest among treatments, were 0.54 dS·m^-1 during the 1^st measurement time and 0.82 dS·m^-1 during the 2^nd measurement time. In summary, the adjustment of nutrient solution EC to 1.0 dS·m^-1 was desirable for best growth of ginseng seedlings when a mixture of peat moss + perlite (7:3, v/v) was used as root medium and leaching percentage was adjusted to 20-30%.