The properties of ginsenosides in ginseng garden soil: accumulation, persistence and behaviour

Abstract

Background & aims: Ginsenosides are triterpene saponins produced by ginseng (Panax spp.). Ginsenosides are secreted into the soil during ginseng growth and are mildly anti-fungal and autotoxic. While an ecological role for ginsenosides in maintenance of the sparse density growth habit of wild ginseng populations can be inferred, the consequence of ginsenoside accumulation in densely populated commercial ginseng gardens remains unknown. The potential for residual ginsenosides in former ginseng gardens to contribute to ginseng replant disease (GRD), a condition in which a new ginseng crop cannot be successfully cultivated in a garden used for ginseng cultivation in the past, has been suggested. However, the extent to which ginsenosides accumulate in ginseng garden soil and persist beyond harvest is poorly documented.

Methods: We developed an extraction protocol to extract ginsenosides from ginseng garden soil, and established the behaviour of ginsenosides in soil in controlled experiments using ginseng garden soil packed into columns.

Results: Ginsenosides accumulate throughout the first three and a half years of ginseng cultivation and decline during the fourth year. Residual ginsenosides present in garden soil at the time of harvest are largely gone by the following spring. Soil column data revealed that sandy-loam soil has capacity to bind and retain ginsenosides, and that protopanaxatriol-type ginsenosides are more mobile than the protopanaxadiol-type.

Conclusion: Ginsenosides accumulate in ginseng garden soil during cultivation, but do not persist. Our data suggest that the impact of ginsenosides on the establishment of GRD occurs during crop growth rather than during the time between plantings.

Supplementary information: The online version contains supplementary material available at 10.1007/s11104-024-07025-7.

Keywords: GRD; Ginseng; Ginseng replant disease; Ginsenosides; Panax quinquefolius; Soil extraction.

Fig. 1

Original Protocol-Optimized Protocol Comparison. Sandy-loam soils spiked with ginsenosides were extracted using either an original protocol based on (Nicol et al. 2003) or the optimized extraction protocol described in Materials & Methods. Bars are the sum of all nine ginsenosides measured (Re, Rg1, F11, Rb1, Rb2, Rc, Rd, Gyp.XVII and F2), after adjustment for extraction efficiency. Data (N=10) are represented by a median (horizontal line), interquartile ranges (box edges), and ranges (whiskers)

Fig. 2

Ginsenoside Accumulation and Persistence in Commercial Garden Soil during Ginseng Cultivation and Beyond. Ginsenosides were extracted from commercial ginseng garden soils collected throughout the four-year cultivation cycle, and for one year post harvest. Three individual gardens were monitored and are displayed as Site 1-3. Only post-harvest soil from Sites 1 and 3 were available for analysis. Data were log transformed (log₁₀(x +1)). Bars represent the mean of five replicate extractions ± SEM. The amount of ginsenoside at each time point was compared to that found at the corresponding “planting” timepoint for each site using the Friedman test with Dunn’s post-hoc test. * = P<0.05

Fig. 3

Behaviour of Ginsenosides in Flow-through Soil Columns. Increasing amounts of total ginsenoside (1, 2, 10, 20 and 100 mg of total ginsenoside on column) were applied to sandy-loam soil columns (200 g, 3.8 x 30 cm) and eluted with water over 10 weeks. A-E, ginsenoside composition of flow through collected over 10 weeks from columns loaded with 1 (A), 2 (B), 10 (C), 20 (D) or 100 (E) mg total ginsenoside. F-J, ginsenoside composition of soil cores from columns loaded with 1 (F), 2 (G), 10 (H), 20 (I) or 100 (J) mg total ginsenoside and eluted with water over 10 weeks. After 10 weeks of elution, columns were frozen and sectioned into 2.5 cm discs prior to ginsenoside extraction. Bars are the means of 3 replicates ± SEM (N=3)