Research Article

Korean Journal of Plant Resources. 1 December 2020. 651-658
https://doi.org/10.7732/kjpr.2020.33.6.651

ABSTRACT


MAIN

  • Introduction

  • Materials and Methods

  •   Plant materials

  •   Soil analysis

  •   Morphology

  •   Ginsenoside analysis

  •   Statistical analysis

  • Results and Discussion

  •   Soil properties

  •   Morphological characteristics

  •   Ginsenoside contents

  •   Correlation between soil properties and growth characteristics of wild-simulated ginseng

  •   Correlation between growth characteristics and ginsenoside contents of wild-simulated ginseng

Introduction

Wild-simulated ginseng (Panax ginseng C.A. Meyer), belonging to Araliaceae, has been defined as a ginseng propagated in forest without the use of any artificial facilities such as light barriers from the Korea Forest Service (KOFPI, 2013). Additionally, wild-simulated ginseng is managed by the Korea Forest Service by selection of cultivation sites, seeds, seeding, cultivation management, quality inspection, and distribution (NIFoS, 2018). Recently, consumers are highly interested in clean forest products, and wild-simulated ginseng is in great demand among many forest products (Kim et al., 2019a). Therefore, the Korea Forest Service has established ‘The Industry Development Countermeasure of Wild-simulated Ginseng’ to carry out scientific research such as standard cultivation, processing, phytochemistry and pharmacology to enhance the cultivation (KFS, 2019).

Cultivation studies of wild-simulated ginseng have been carried out based on the correlation between direct seeding, transplanting, soil properties, soil bacterial community and growth characteristics (Kim et al., 2019a; Kim et al., 2019b, 2019c). The studies on ginsenoside have been reported based on the difference between its accumulation in wild-simulated ginseng and cultivated ginseng (Jeong et al., 2019; Moon, 2015). In addition, Kim et al. (2020) reported the content of ginsenoside were significantly higher in 13-year-old wild-simulated ginseng compare to 7-year-old wild-simulated ginseng. However, comprehensive studies of soil properties, growth characteristics, ginenoside contents of wild-simulated ginseng have not been studied till date.

Hence, in this study, we aimed to investigate the comparative growth characteristics and ginenoside contents of wild-simulated ginseng based on different years by monitoring soil properties of cultivation regions.

Materials and Methods

Plant materials

Seven and 13-year-old wild-simulated ginseng samples were collected in 3 replicates according to their age from six local provinces (Pyeongchang, Yeongwol, Danyang, Munkyeong, Hamyang, Sancheong) in South Korea during July to August 2019.

Soil analysis

Soil samples were collected from 6 different cultivation regions of wild-simulated ginseng in 3 replicates according to their age (7 and 13-year-old). Surface soil was removed and soil was collected at a depth within 20 ㎝. The soil samples were passed through 2 ㎜ sieve and air-dried at room temperature. The soil physico-chemical properties analysis such as soil pH, electric conductivity (EC), organic matter (OM), total nitrogen (TN), available phosphate (Avail. P2O5), exchangeable cation and cation exchange capacity (CEC) were performed following standard analysis manual of the Rural Development Administration (RDA), South Korea (RDA, 2013).

Morphology

Quantitative characters of 7 and 13-year-old wild-simulated ginseng such as rhizome length, root length, root diameter and dry weight were measured using digital calipers and balance (Fig. 1). The cross-section area, surface area and volume of root were measured using an EPSON scanner (Expression 12,000XL) and WinRHIZOTM Pro software (version 2017, Regent Instruments, Canada) (Kim et al., 2019b; Wisam et al., 2018).

https://static.apub.kr/journalsite/sites/kjpr/2020-033-06/N0820330611/images/kjpr_33_06_11_F1.jpg
Fig. 1

Morphology characteristics of wild-simulated ginseng. (1) 7-year-old, (2) 13-year-old, (3) morphological characteristics measured in the study (1-3 were cited from Kim et al., 2020).

Ginsenoside analysis

Dried roots were pulverized with a grinder, and then sieved through a no. 80 mesh. The powdered from of 36 samples (ca. 0.2 g) were extracted with 10 mL of 80% (v/v) methanol in an ultrasonic bath (JAC-5020, KODO, Korea) for 60 min. After centrifugation, the supernatant was separated, and it was defatted through a 0.2 ㎛ membrane filter unit. An aliquot of 10 μL was analyzed using HPLC with a UV detector.

Standards of ginsenosides (G-Rb1, Rb2, Rc, Rd, Re, Rf, Rg1, Rg2, Rg3, Rh1, Rh2, F2) were purchased from ChromaDex (USA). HPLC-grade acetonitrile, methanol, and distilled water were purchased from J.T.Baker (USA) (Fig. 2). Standard working solutions for HPLC-UV were prepared by diluting the stock solutions in methanol to obtain concentration range of 10, 25, 50, 100 ㎍/mL for 12 ginsenosides.

https://static.apub.kr/journalsite/sites/kjpr/2020-033-06/N0820330611/images/kjpr_33_06_11_F2.jpg
Fig. 2

Chemical structures of portopanaxadiol (PPT) and protopanaxatriol (PPT)-type ginsenoside (Glc: β-D-glucopyranosyl, Arp: α-L-arabinopyranosyl, Araf: α-L-arabinofuranosyl, Rha: α-L-rhamnopyranosyl).

Ginsenoside data were obtained using an Ultimate 3000 HPLC (Thermo Dionex, USA) with a UV detector. The analytical conditions for recording chromatogram of the marker compounds were as follows: Quantitative analysis was carried out using a Inno C-18 column (4.6 × 250 ㎜, 5 ㎛, YoungjinBiochrom, Korea). The mobile phase was a binary eluent of water (A) and acetonitrile (B) with gradient conditions as follows: 0-1 min, 5% B; 1-45 min, 70% B; 45-50 min, 95% 50-55 min, 95% B; 55-57 min, 5% B; 57-60 min, 5% B; flow rate of 1.0 mL/min. The detection wavelength was 210 ㎚, and the injection volume was 10 μL.

Statistical analysis

Data are expressed as means ± standard error (S.E.). Statistical analysis was performed using the Statistical Analysis System (SAS, version 9.4, SAS Institute, Cary, NC, USA) software for one-way ANOVA and t-test, with statistical significance set at p < 0.05. The correlation between soil parameters, growth characteristics and ginsenoside contents of wild-simulated ginseng was confirmed by Pearson’s correlation coefficient using IBM SPSS Statistics (version 25, IBM Corp., Armonk, New York, USA).

Results and Discussion

Soil properties

The soil physico-chemical properties of 6 different cultivation regions based on the age of wild-simulated ginseng are summarized in Table 1. Soil samples were classified as sandy loam and sandy clay loam according to the soil texture. Soil pH of all cultivation regions has determinsed as acidic or slightly acidic soils, ranging from 4.73 to 5.69. Organic matter (OM), TN and CEC were significantly higher in 13-year-old wild-simulated ginseng cultivation regions compared to 7-year-old wild-simulated ginseng cultivation regions. On the other hand, the soil sodium content showed a significantly difference, but all soil samples were non-saline soil (EC < 2.0 dS/m). Soil EC, available P2O5, potassium (K), calcium (Ca) and magnesium (Mg) showed no significant difference according to the different ages of wild-simulated ginseng.

Table 1.

Soil chemical properties of 6 different cultivation regions according to age of wild-simulated ginseng

Cultivation
fields
Age Soil
texture
pH ECz OMy TNx Avail.
P2O5w
Exchangeable cation CECv
K Ca Mg Na
(1:5) (dS/m) (%) (%) (㎎/㎏) ------------------- (cmol+/㎏) ------------------- (cmol+/㎏)
PCu 7 Sandy loam 5.26±
0.03ar
0.02±
0.00b
16.8±
1.36a
0.60±
0.06a
61.5±
6.24b
0.32±
0.03a
4.78±
1.02a
0.63±
0.14a
0.19±
0.11a
42.7±
3.26a
13 Sandy loam 5.43±
0.09a
0.03±
0.00a
16.9±
0.35a
0.65±
0.03a
268.9±
70.4a
0.60±
0.23a
7.22±
0.08a
0.70±
0.08a
0.05±
0.00a
40.9±
1.39a
YW 7 Sandy clay loam 5.34±
0.10a
0.03±
0.00a
6.45±
0.24b
0.23±
0.01b
11.9±
0.47b
0.24±
0.04a
3.02±
0.79a
0.72±
0.16a
0.27±
0.08a
22.5±
1.03b
13 Sandy clay loam 5.29±
0.09a
0.04±
0.01a
9.76±
0.86a
0.35±
0.03a
75.9±
7.84a
0.18±
0.03a
1.86±
0.46a
0.36±
0.04a
0.03±
0.01b
29.3±
1.49a
DY 7 Sandy clay loam 5.61±
0.14a
0.02±
0.00a
3.81±
0.41b
0.15±
0.01b
8.6±
0.31b
0.15±
0.0.4b
4.70±
0.39a
1.06±
0.02a
0.08±
0.02a
14.3±
1.77a
13 Sandy clay loam 5.69±
0.11a
0.02±
0.00a
5.03±
0.13a
0.20±
0.01a
108.0±
24.5a
0.31±
0.03a
4.86±
0.55a
0.71±
0.05b
0.02±
0.00b
17.8±
0.99a
MK 7 Sandy loam 5.53±
0.08a
0.03±
0.00a
9.2±
0.49b
0.35±
0.01b
115.7±
6.95a
0.23±
0.06a
3.65±
0.94a
0.63±
0.19a
0.23±
0.07a
28.7±
0.73a
13 Sandy loam 5.17±
0.04b
0.02±
0.00a
11.9±
0.43a
0.43±
0.01a
131.9±
3.80a
0.13±
0.01a
0.95±
0.08b
0.23±
0.02a
0.04±
0.01a
31.7±
1.08a
HY 7 Sandy loam 4.77±
0.04b
0.02±
0.00b
9.4±
0.49b
0.35±
0.02b
129.3±
15.2a
0.10±
0.01b
0.37±
0.03b
0.11±
0.01a
0.11±
0.08a
27.5±
1.11b
13 Sandy loam 5.29±
0.05a
0.05±
0.01a
12.8±
0.21a
0.48±
0.01a
78.4±
13.4a
0.30±
0.04a
6.99±
1.53a
1.07±
0.37a
0.07±
0.02a
33.5±
0.39a
SC 7 Sandy clay loam 4.75±
0.09a
0.02±
0.00a
3.29±
1.05b
0.14±
0.03b
12.1±
2.86a
0.08±
0.01a
0.24±
0.07a
0.05±
0.01a
0.05±
0.02a
12.7±
3.03b
13 Sandy clay loam 4.73±
0.04a
0.02±
0.00a
8.73±
1.06a
0.34±
0.04a
23.2±
9.62a
0.11±
0.02a
0.10±
0.02a
0.05±
0.01a
0.06±
0.02a
26.0±
2.22a
Total 7 5.19±
0.09a
0.02±
0.00a
7.9±
0.99b
0.30±
0.04b
52.6±
12.7a
0.17±
0.02a
2.41±
0.45a
0.48±
0.09a
0.15±
0.03a
23.1±
1.94b
13 5.21±
0.08a
0.03±
0.01a
11.4±
1.17a
0.43±
0.05a
94.9±
20.5a
0.27±
0.05a
3.39±
0.70a
0.53±
0.10a
0.04±
0.01b
30.8±
2.16a

zEC: Electric conductivity; yOM: Organic matter; xTN: Total nitrogen; wAvail. P2O5: Available phosphate; vCEC: Cation exchange capacity; uCultivation regions: PC (Pyeongchang), YW (Yeongwol), DY (Danyang), MK (Munkyeong), HY (Hamyang), SC (Sancheong).

rValue in each column with different letters are statistically significant differences (p <0.05) among the treatments according to least significant difference (LSD).

Morphological characteristics

According to a survey on the growth characteristics of wild-simulated ginseng, rhizome length was recorded 9.7 ± 0.31 ~ 32.8 ± 0.65 ㎜. Length, diameter and dry weight of root were 16.7 ± 0.59 ~ 33.5 ± 3.39 ㎝, 7.50 ± 1.03 ~ 12.3 ± 0.67 ㎜, 7.50 ± 1.03 ~ 12.3 ± 0.67 ㎜, respectively. Cross-section area, surface area, volume of root were 9.7 ± 0.97 ~ 34.1 ± 5.28 ㎠, 30.6 ± 3.03 ~ 107.1 ± 16.6 ㎠, 1.21 ± 0.81 ~ 3.50 ± 0.33 ㎤, respectively (Table 2). Growth characteristics such as rhizome length, root length, root diameter, dry weight and volume were significantly higher in 13-year-old wild-simulated ginseng.

Table 2.

Growth characteristic according to age of wild-simulated ginseng in 6 different cultivation regions

Cultivation
fields
Age Growth characteristics
Rhizome
length
Root length Root diameter Dry weight of
root
Cross-section
area
Surface area Volume
(㎜) (㎝) (㎜) (g) (㎝2) (㎝2) (㎝3)
PCz 7 20.3±1.98by 22.8±1.99a 7.50±1.03a 0.97±0.14b 18.6±3.59a 58.4±11.3a 1.65±0.28b
13 32.8±0.65a 33.5±3.39a 9.53±0.99a 1.87±0.18a 34.1±5.28a 107.1±16.6a 3.31±0.52a
YW 7 18.0±2.12a 23.2±2.17a 8.7±0.45a 0.90±0.10a 22.3±5.18a 70.1±16.3a 2.11±0.57a
13 20.3±5.56a 23.2±2.67a 12.1±1.81a 1.11±0.22a 16.8±2.95a 52.8±9.2a 1.94±0.04a
DY 7 17.8±1.86a 17.2±2.18a 10.9±1.29a 1.13±0.21a 15.6±1.12a 49.1±3.51a 1.56±0.10a
13 21.3±4.24a 18.9±3.40a 9.4±1.71a 1.02±0.06a 22.8±7.24a 71.6±22.7a 2.21±0.37a
MK 7 19.9±6.13a 18.6±2.21b 11.7±1.10a 1.21±0.08a 22.9±4.08a 72.1±12.8a 2.33±0.28a
13 25.2±8.89a 29.9±1.31a 11.1±0.84a 1.20±0.05a 19.6±0.38a 61.5±1.20a 2.66±0.05a
HY 7 17.8±0.97a 18.9±1.51a 9.3±0.69a 1.04±0.10b 25.2±3.33a 79.2±10.4a 2.26±0.25a
13 25.1±2.85a 25.1±3.17a 11.9±1.33a 1.69±0.13a 20.4±2.30a 64.2±7.2a 2.22±0.24a
SC 7 9.7±0.31b 16.7±0.59a 10.4±1.19a 0.79±0.09b 9.7±0.97b 30.6±3.03b 1.21±0.18b
13 30.5±2.51a 21.6±3.64a 12.3±0.67a 1.87±0.16a 28.9±3.12a 90.7±9.78a 3.50±0.33a
Total 7 15.6±1.55b 19.6±0.89b 9.8±0.48a 1.01±0.05b 19.1±1.72a 59.9±5.40a 1.86±0.15b
13 25.8±2.00a 25.4±1.59a 11.1±0.53a 1.46±0.10a 23.8±2.03a 74.7±6.37a 2.64±0.18a

zCultivation field: PC (Pyeongchang), YW (Yeongwol), DY (Danyang), MK (Munkyeong), HY (Hamyang), SC (Sancheong).

yValue in each column with different letters are statistically significant differences (p <0.05) among the treatments according to least significant difference (LSD).

Ginsenoside contents

The HPLC-UV method was used for detecting 12 ginsenoside (G-Rb1, Rb2, Rc, Rd, Re, Rf, Rg1, Rg2, Rg3, Rh1, Rh2, F2) standards. Ginsenoside identities in the HPLC-UV chromatogram were confirmed by comparing retention times and UV spectra chromatograms of the peaks with those of the standards (Fig. 3). The analysis was conducted in triplicate and the results are shown in Table 3. Wild-simulated ginseng contained G-Rb1 at 0.91 ± 0.01 ~ 4.39 ± 0.16 ㎎/g, Rb2 at 3.80 ± 0.14 ~ 11.2 ± 0.33 ㎎/g, Rc at 1.15 ± 0.03 ~ 3.38 ± 0.13 ㎎/g, Rd at 0.55 ± 0.01 ~ 2.64 ± 0.11 ㎎/g, Re at 3.33 ± 0.06 ~ 6.86 ± 0.02 ㎎/g, Rf at 0.71 ± 0.01 ~ 2.02 ± 0.01 ㎎/g, Rg1 at 2.01 ± 0.04 ~ 6.46 ± 0.07 ㎎/g, Rg2 at 0.22 ± 0.01 ~ 0.72 ± 0.11 ㎎/g. In particular, G-Rb2, Re and Rg1 had high levels compared to the others. In contrast, G-Rg3 and Rh2 were not detected in any of the samples. According to the ginsenoside study based on the time of collection and cultivation conditions of mountain ginseng, it was reported that G-Rb1, Rb2, Rc and Re were mainly distributed (Chang, 1998; Nam, 1996). This study also confirmed that the results were consistent with previous studies because on the high content of Rb2, Re, and Rg1.

https://static.apub.kr/journalsite/sites/kjpr/2020-033-06/N0820330611/images/kjpr_33_06_11_F3.jpg
Fig. 3

HPLC chromatograms of ginsenosides in wild-simulated ginseng (A: 7-year-old, B: 13-year-old).

Table 3.

Ginsenoside content according to age of wild-simulated ginseng in 6 different cultivation regions

Cultivation
fields
Age Content of ginsenosides
Rb1 Rb2 Rc Rd Re Rf Rg1 Rg2 Rg3 Rh1 Rh2 F2(AS)
(㎎/g) (㎎/g) (㎎/g) (㎎/g) (㎎/g) (㎎/g) (㎎/g) (㎎/g) (㎎/g) (㎎/g) (㎎/g) (㎎/g)
PCz 7 2.93±
0.11by
4.66±
0.04b
2.55±
0.04b
2.14±
0.08b
3.33±
0.06b
0.80±
0.01b
3.18±
0.01b
0.31±
0.00b
NDx 0.04±
0.00a
ND 0.04±
0.00b
13 3.71±
0.08a
6.89±
0.22a
3.20±
0.06a
2.53±
0.04a
4.45±
0.07a
1.11±
0.01a
3.35±
0.03a
0.40±
0.01a
ND 0.04±
0.00a
ND 0.06±
0.00a
YW 7 4.20±
0.19a
5.77±
0.20b
3.38±
0.13a
2.64±
0.11a
4.30±
0.02b
0.89±
0.00a
2.38±
0.04b
0.50±
0.01a
ND 0.03±
0.00b
ND 0.05±
0.00a
13 4.39±
0.16a
8.70±
0.31a
3.32±
0.11a
1.83±
0.07b
4.88±
0.06a
1.53±
0.02b
4.65±
0.05a
0.32±
0.00b
ND 0.04±
0.00a
ND 0.06±
0.00a
DY 7 1.78±
0.11a
3.80±
0.14b
1.38±
0.06b
1.06±
0.02a
3.06±
0.02b
0.71±
0.01b
2.17±
0.03b
0.31±
0.01a
ND 0.03±
0.00b
ND 0.06±
0.00
13 2.30±
0.16a
6.71±
0.25a
1.90±
0.09a
0.55±
0.01b
3.17±
0.05a
1.46±
0.03a
4.95±
0.03a
0.22±
0.01b
ND 0.04±
0.00a
ND ND
MK 7 1.31±
0.07b
5.8±
0.10b
1.74±
0.04b
1.07±
0.08b
4.68±
0.02b
1.07±
0.02b
2.86±
0.04b
0.53±
0.01b
ND ND ND 0.04±
0.00a
13 2.44±
0.10a
11.2±
0.33a
2.60±
0.11a
1.37±
0.06a
6.76±
0.06a
2.02±
0.01a
6.46±
0.07a
0.71±
0.00a
ND ND ND 0.03±
0.00a
HY 7 1.02±
0.01b
5.78±
0.03b
1.34±
0.01b
1.12±
0.01b
6.33±
0.04b
0.96±
0.01b
2.01±
0.04b
0.72±
0.01a
ND ND ND 0.03±
0.00
13 3.50±
0.09a
8.29±
0.22a
2.92±
0.09a
1.28±
0.02a
6.86±
0.02a
1.32±
0.02a
4.30±
0.12a
0.44±
0.01b
ND 0.05±
0.00
ND ND
SC 7 0.91±
0.01b
4.59±
0.14b
1.15±
0.03b
0.76±
0.03a
4.15±
0.01b
0.95±
0.02b
2.96±
0.05b
0.46±
0.00b
ND ND ND 0.02±
0.00a
13 1.33±
0.03a
7.84±
0.11a
1.81±
0.05a
0.85±
0.02a
4.90±
0.13a
1.03±0.01a 3.61±0.03a 0.48±
0.00a
ND ND ND 0.01±
0.00b
Total 7 2.02±
0.29b
5.07±
0.19b
1.92±
0.19b
1.47±
0.17a
4.31±
0.26b
0.90±
0.03b
2.59±
0.11b
0.47±
0.03b
ND 0.02±
0.00a
ND 0.04±
0.01a
13 2.94±
0.25a
8.27±
0.37a
2.62±
0.15a
1.40±
0.16a
5.17±
0.32a
1.41±
0.08a
4.55±
0.25a
0.43±
0.04a
ND 0.03±
0.00a
ND 0.03±
0.01a

zCultivation field: PC (Pyeongchang), YW (Yeongwol), DY (Danyang), MK (Munkyeong), HY (Hamyang), SC (Sancheong).

yValue in each column with different letters are statistically significant differences (p < 0.05) among the treatments according to least significant difference (LSD).

xND: not detected.

As for ginsenoside contents of wild-simulated ginseng, 13-year-old roots had significantly higher G-Rb1, Rb2, Rc, Rd, Re, Rf, Rg1 content compared to 7-year-old roots. In contrast, G-Rg2 was significantly higher in 7-year-old than 13-year-old. In another study based on the correlation between the ginsenoside contents and growth characteristics of wild-simulated ginseng, 13-year-old roots were found to be higher in G-Rb1, Rb2, Rc, Rd, Re, Rf, Rg1 and Rg2 content compared to 7-year-old roots (Kim et al., 2020). Therefore, the chemical composition of ginsenosides of wild-simulated ginseng confirmed the results similar to those of previous studies.

Correlation between soil properties and growth characteristics of wild-simulated ginseng

The results of correlation analysis between soil properties and growth characteristics of wild-simulated ginseng are represented in Table 4. Among the soil properties, OM, TN and CEC were shown to have a significantly positive correlation with growth characteristics of wild-simulated ginseng. Soil organic matter had shown significant positive correlation with rhizome length (r = 0.495, p < 0.01), root length (r = 0.659, p < 0.01), root dry weight (r = 0.489, p < 0.01), cross-section area (r = 0.463, p < 0.01), surface area (r = 0.463, p < 0.01) and root volume (r = 0.468, p < 0.01) of wild-simulated ginseng. Soil total nitrogen content had shown significant positive correlation with rhizome length (r = 0.527, p < 0.01), root length (r = 0.660, p < 0.01), root dry weight (r = 0.509, p < 0.01), cross-section area (r = 0.466, p < 0.01), surface area (r = 0.466, p < 0.01) and root volume (r = 0.463, p < 0.01) of wild-simulated ginseng. In case of CEC, it had shown significant positive correlation with rhizome length (r = 0.488, p < 0.01), root length (r = 0.649, p < 0.01), root dry weight (r = 0.509, p < 0.01), cross-section area (r = 0.512, p < 0.01), surface area (r = 0.512, p < 0.01) and root volume (r = 0.521, p < 0.01) of wild-simulated ginseng. Soil organic matter and total nitrogen are essential nutrients during the growth of ginseng, and the organic matter content in the root layer of ginseng has correlation with the total nitrogen contents (Cheng et al., 2011). Kim et al. (2020) reported that the growth characteristics of wild-simulated ginseng had shown significant positive correlation with soil OM, TN and CEC. Hence, the previous studies support that the OM, TN and CEC have a significant correlation with growth of wild-simulated ginseng.

Table 4.

Correlation between soil properties and growth characteristics of wild-simulated ginseng

Soil
properties
Correlation coefficient (r)z
Growth characteristics
Rhizome length Root length Root diameter Dry weight of
root
Cross-section
area
Surface area Volume
pH 0.105 (0.542) -0.114 (0.509) 0.080 (0.644) -0.127 (0.462) -0.108 (0.529) -0.108 (0.529) -0.190 (0.267)
ECy 0.355 (0.034)* 0.238 (0.162) 0.141 (0.412) 0.416 (0.012)* 0.208 (0.224) 0.208 (0.224) 0.238 (0.162)
OMx 0.495 (0.002)** 0.659 (0.000)** -0.160 (0.351) 0.489 (0.002)** 0.463 (0.004)** 0.463 (0.004)** 0.468 (0.004)**
TNw 0.527 (0.001)** 0.660 (0.000)** -0.152 (0.376) 0.509 (0.002)** 0.466 (0.004)** 0.466 (0.004)** 0.463 (0.004)**
Avail. P2O5v 0.320 (0.057) 0.312 (0.064) -0.011 (0.950) 0.113 (0.513) 0.175 (0.307) 0.175 (0.307) 0.187 (0.276)
K 0.309 (0.066) 0.436 (0.008)** -0.001 (0.994) 0.308 (0.068) 0.287 (0.089) 0.287 (0.089) 0.192 (0.262)
Ca 0.206 (0.227) 0.103 (0.551) -0.032 (0.851) 0.202 (0.238) 0.087 (0.614) 0.087 (0.614) -0.032 (0.853)
Mg 0.090 (0.600) 0.026 (0.879) 0.088 (0.608) 0.149 (0.385) 0.024 (0.887) 0.024 (0.887) -0.085 (0.623)
Na -0.365 (0.029)* -0.046 (0.789) -0.148 (0.391) -0.213 (0.213) 0.105 (0.543) 0.105 (0.543) -0.025 (0.883)
CECu 0.488 (0.003)** 0.649 (0.000)** -0.102 (0.552) 0.509 (0.002)** 0.512 (0.001)** 0.512 (0.001)** 0.521 (0.001)**

zCorrelation coefficient (r) written are significantly correlated between the variables compared. Negative values denote negative correlation and positive values denote positive correlation. Values in bracket means p value (**p < 0.01, *p < 0.05).

yEC: Electric conductivity; xOM: Organic matter; wTN: Total nitrogen; vAvail. P2O5: Available phosphate; uCEC: Cation exchange capacity.

Correlation between growth characteristics and ginsenoside contents of wild-simulated ginseng

The correlation analysis between growth characteristics and ginsenoside content of wild-simulated ginseng (7-year-old and 13-year-old) had shown a significant positive correlation (Table 5). Root length of wild-simulated ginseng had significant positive correlation with ginsenoside Rb1 (r = 0.491, p < 0.01), Rb2 (r = 0.507, p < 0.01), Rc (r = 0.611, p < 0.01), Rd (r = 0.502, p < 0.01), Rf (r = 0.383, p < 0.05) and Rg1 (r = 0.395, p < 0.05). Among the ginsenoside, Rb2 had shown significant positive correlation with rhizome length (r = 0.396, p < 0.05), root dry weight (r = 0.357, p < 0.05) and root volume (r = 0.467, p < 0.01). Kim et al. (2020) reported that the root length of wild-simulated ginseng has significant positive correlation with ginsenoside Rd and Rf. Alongside, ginsenoside Rb2 had shown significant positive correlation with root dry weight, cross-section area, surface area, volume of wild-simulated ginseng. Overall, soil OM, TN and CEC of the cultivated regions had a significantly positive correlation with the growth of wild-simulated ginseng. In addition, the root length of wild-simulated ginseng showed significant positive correlation with the content of ginsenoside.

Table 5.

Correlation between growth characteristics and ginsenoside contents of wild-simulated ginseng

Ginsenoside Correlation coefficient (r)z
Growth characteristics
Rhizome length Root length Root diameter Dry weight of root Cross-section area Surface area Volume
Rb1 0.068 (0.694) 0.491 (0.002)** -0.102 (0.555) 0.128 (0.456) 0.115 (0.506) 0.115 (0.505) 0.083 (0.630)
Rb2 0.396 (0.017)* 0.507 (0.002)** 0.292 (0.084) 0.357 (0.032)* 0.186 (0.277) 0.186 (0.278) 0.467 (0.004)**
Rc 0.158 (0.359) 0.611 (0.000)** -0.064 (0.710) 0.241 (0.157) 0.215 (0.209) 0.215 (0.208) 0.242 (0.154)
Rd -0.004 (0.980) 0.502 (0.002)** -0.305 (0.070) 0.072 (0.678) 0.214 (0.209) 0.215 (0.209) 0.115 (0.504)
Re 0.199 (0.245) 0.312 (0.064) 0.275 (0.105) 0.280 (0.098) 0.122 (0.478) 0.122 (0.478) 0.285 (0.092)
Rf 0.275 (0.104) 0.383 (0.021)* 0.230 (0.178) 0.101 (0.556) 0.003 (0.986) 0.003 (0.986) 0.233 (0.172)
Rg1 0.324 (0.054) 0.395 (0.017)* 0.192 (0.261) 0.147 (0.392) -0.020 (0.910) -0.020 (0.910) 0.221 (0.195)
Rg2 -0.016 (0.927) 0.124 (0.472) 0.106 (0.540) 0.033 (0.847) 0.107 (0.533) 0.107 (0.533) 0.228 (0.180)
Rh1 0.060 (0.727) 0.243 (0.154) -0.169 (0.323) 0.113 (0.513) 0.081 (0.637) 0.082 (0.636) -0.076 (0.661)
F2(AS) -0.122 (0.478) 0.209 (0.221) -0.099 (0.565) -0.088 (0.609) 0.054 (0.752) 0.055 (0.751) -0.030 (0.864)

zCorrelation coefficient (r) written are significantly correlated between the variables compared. Negative values denote negative correlation and positive values denote positive correlation. Values in bracket means p value (**p <0.01, *p <0.05).

These results showed that the growth and ginsenoside contents of wild-simulated ginseng increased with the longer duration of cultivation time with additional characteristics of high soil OM, TN and CEC in cultivation regions. In addition, this study was able to investigate the correlation between growth and ginsenoside content of wild-simulated ginseng based on the soil characteristics of the cultivation regions.

Acknowledgements

This work was supported by the research of National Institute of Forest Science (NIFoS) (FP0802-2017-08).

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