Influence of nutrient solution concentration on growth and tissue mineral content of Panax ginseng seedlings cultured in a root medium containing peat and perlite

Abstract

There is an increasing trend of producing seedlings of Panax ginseng in amended root media in raised beds. Precise control of the fertility of root media is essential for raising healthy seedlings, especially when inert media with a low buffering capacity are used. The objective of this study was to investigate the influence of fertility (as measured by EC) of the nutrient solution used for seedling production. One thousand eight hundred seeds were sown for five treatments and a control (300 seeds per treatment, 3 × 3 cm spacing) using root medium [composed of peat moss + perlite (7:3, v/v)] on raised beds with measurements, 120 × 60 × 25 cm (L × W × H) on Mar 9, 2018. Five nutrient solutions with different strengths (0.4, 0.6, 0.8, 1.0, 1.2 dS m−1 EC) were prepared with ground water (0.25 dS m−1) and a fertilizer stock solution (2 mM NH4+-N, 12 mM NO3−-N, 1 mM H2PO4−, 8 mM K+, 2 mM Ca2+, 1 mM Mg2+, 1 mM SO42−). Fertigation of the beds started on May 21 using each of six nutrient solutions and fertigation frequencies were controlled using an EC5 soil moisture sensor. The stock solutions were automatically supplied for 30 min when the volumetric water content decreased to 36%. Plant growth measurement and soil analyses were carried out twice: first at 144 days and subsequently at 197 days (from the day of seeds sown). For the first growth measurement, elevated EC in the fertilizer solution resulted in enhanced growth, but statistical differences among treatment solutions were not significant except for the case of ground water. In the second measurement, the seedling growth in terms of dry weight of above- and below-ground plant parts increased significantly in plants treated with the 1.0 dS m−1 EC solution and decreased in plants treated with the (1.2 dS m−1 EC) solution. In both the first and second measurements, the ground tissue nutrient content (T-N, P, K and Ca) was significantly different among treatments. The EC of root media in the case of 1.0 dS m−1 treatment, where the seedling growth was the highest among treatments, was 0.54 dS m−1 at the first measurement and 0.82 dS m−1 at the second measurement. In summary, a root medium with a mixture of peat moss + perlite (7:3, v/v), a leaching percentage of 20–30%, and a nutrient solution with a concentration of 1.0 dS m−1 EC is suitable for the healthy growth of ginseng seedlings.