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Effect of vermicompost application on root growth and ginsenoside content of Panax ginseng
Journal of Environmental Management 234 (2019) 458–463
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Journal of Environmental Management journal homepage: www.elsevier.com/locate/jenvman
Research article
Effect of vermicompost application on root growth and ginsenoside content of Panax ginseng
T
Jinu Eo∗, Kee-Choon Park National Institute of Agricultural Sciences, RDA, Wanju, 55365, Republic of Korea
A R T I C LE I N FO
A B S T R A C T
Keywords: Ginsenoside Paddy-converted field Panax ginseng Root rot disease Vermicompost
Vermicomposts are valuable by-products of organic wastes and can be used to improve soil environments in ginseng production. We compared the effects of food waste vermicompost (FWV), cow manure vermicompost (CMV) and paper sludge vermicompost (PSV) on several ginseng root production variables. Interactions between soil chemical properties, root growth, ginsenoside content and plant mineral content were also investigated. In the PSV treatment, the root yield increased by 40 t ha−1 compared to the untreated control. Nitrate concentration correlated negatively with root yield, and none of the vermicompost treatments differed significantly from the control in terms of root loss. Soil pH correlated positively with root weight, and total ginsenoside content did not vary among treatments, although some individual ginsenosides did differ among treatments. Root iron content correlated strongly with total ginsenoside content, and total ginsenoside content correlated negatively with root yield. Overall, our results showed that the root yield increase was not due to nutrient increase. Vermicompost was safe to use in relation to root rot disease, and it favourably elevated the pH of fields converted from rice paddies to ginseng production. Ginsenoside was not involved in defence mechanisms against root rot disease. Root iron content may have been involved in the metabolism of ginsenoside, and there was an apparent trade-off between ginsenoside content and root yield. Finally, vermicompost application altered resource allocation and soil chemical properties, which led to novel interactions between root parameters and components.
1. Introduction Panax ginseng, which is used as an herbal supplement, is cultured in Asia, Europe and North America (Baeg and So, 2013). Ginseng root production requires root growth and control of root rot disease. Root growth is influenced by soil properties such as nutrient content, pH and soil moisture (Lee and Mudge, 2013). Root rot disease has been reported as a major threat to ginseng and is primarily caused by fungal pathogens such as Cylindrocarpon destructans and Fusarium solani (Eo and Park, 2013). Damage caused by root rot disease is often most severe in replanted fields, and disease incidence can be reduced using cultural measures. Ginseng is commonly produced in fields converted from paddies because it is a good option for controlling root rot disease. Ginsenoside is a triterpenoidic saponin found in various parts of ginseng plants such as berries, roots and leaves (Chuang and Sheu, 1994). Ginsenoside is believed to have pharmacological properties such as antioxidant and anticarcinogenic effects on humans (Attele et al., 1999). In ginseng cultivation, ginsenosides influence ginseng yield through increased nutrient uptake and pathogen resistance. A trade-off
∗
between biomass and ginsenoside content can occur because ginseng plants redistribute available resources for multiple, competing purposes. Ginsenoside plays a defence role against pathogens, pests and plants (Nicol et al., 2002; Yang et al., 2015). Fungal infection promotes production of some forms of ginsenoside in ginseng plants (Jiao et al. 2011, 2015). Organic wastes are produced from industrial processing and stalk removal. For economic and environmental reasons, reusing these wastes benefits crop cultivation. Vermicompost uses these organic wastes and increases the quality of raw waste (Kaviraj, 2003). Vermicomposts, when applied to crops, promote plant growth by improving soil's nutritional and physical properties (Atiyeh et al., 2002; Azarmi et al., 2008). However, plants often show contrasting responses between nutrient content vs. growth and secondary metabolite production (Hofmann and Jahufer, 2011). Moreover, adding organic materials may negatively affect plant yield by promoting pathogenic fungi proliferation via substrate supply (Eo and Park, 2013). Studying root growth, ginsenoside content and root rot disease simultaneously can help us evaluate the benefits of vermicomposts.
Corresponding author. E-mail address: [email protected] (J. Eo).
https://doi.org/10.1016/j.jenvman.2018.12.101 Received 11 September 2018; Received in revised form 28 November 2018; Accepted 26 December 2018 0301-4797/ © 2018 Elsevier Ltd. All rights reserved.
Journal of Environmental Management 234 (2019) 458–463
J. Eo, K.-C. Park
parameters were measured. Harvested roots were washed with tap water. Ten roots with undamaged body shape were weighed. Root rot disease was assessed for all roots by counting roots having brown spots larger than 3 mm in diameter.
Cultural methods have been developed to stabilise yield and ginsenoside content simultaneously (Park et al., 1986; Lee et al., 2012). Here, we tested three types of vermicompost produced from cow manure, food waste and paper sludge, respectively, to develop methods for vermicompost application in ginseng production. We tested the effects of these vermicomposts on root growth, ginsenoside content and root rot disease. Interactions among these parameters have been poorly studied, and environmental control of these interactions is important for maximising ginseng yield. We hypothesised that changes in soil properties by vermicomposts may alter ginseng root growth parameters as well as their interactions with each other and with their environment. We also investigated the correlation of plant mineral content with other parameters because mineral composition influences the level of secondary metabolites by altering degradation and biosynthesis of metabolites (Santos et al., 2011; Zhang et al., 2013).
2.4. Ginsenoside analysis The ginsenoside content was measured using the method of Kim et al. (2012). Ginseng root samples of 0.2 g were freeze-dried, powdered and extracted with 70% MeOH. The suspension was ultrasonicated for 30 min at 50 °C and then centrifuged for 15 min at 13,000 rpm. The supernatant was filtered through a Sep-Pak C18 cartridge (Waters Corp., Milford, MA, USA) and then through a 0.45 μL microfilter (Watman Mini-UniPrep Syringeless Filters, USA). The ginsenoside analysis was conducted using the LC-1100 system (Agilent, Waldbronn, Germany). Chromatographic separations were conducted on a Halo® RP - Amide column (4.6 × 150 mm, 2.7 μm at 50 °C). The mobile phase was established with an eluent (acetonitrile: deionised Water = 30: 70), and the flow rate was 0.5–0.8 mL min−1. UV detection was conducted at 203 nm, and the injected volume was 10 μL. Standard ginsenosides were purchased from a chemical company (ChromaDex Inc., Santa Ana, CA, USA).
2. Materials and methods 2.1. Experiment site Our experiment was conducted in Eumseong Province, Korea. The field was a former paddy which was converted in 2008 when watering ceased. Three compost types were tested: food waste vermicompost (FWV), cow manure vermicompost (CMV) and paper sludge vermicompost (PSV). They were made by composting with a mixture of two earthworm species, Eisenia fetida and Eisenia andrei. FWV was obtained from Hansol Agricultural Cooperative (Asan, Korea), whereas CMV and PSV were obtained from local manufacturers in Ulsan and Cheonan, respectively. The chemical content of each vermicompost is presented at Table 1. Two volumes of vermicompost, 10 and 40 t ha−1, were applied in November 2008. Untreated plots were used as controls. Three replicates of the experiment were established using a randomised block design. The area of each plot was 0.9 m × 3.6 m and one-year-old ginseng seedlings were transplanted at a rate of 35 plants m−2 on 17 March 2009. Rice straw was applied as mulch on the soil surface. Shading facilities were constructed from 23 March to 24 April 2009. Fungicides were applied to control leaf blight and anthracnose during the growing season.
2.5. Data analysis Differences among the treatments were analysed using an LSD test at P = 0.05 if a significant ANOVA result was found. Correlation coefficients were calculated between soil chemical properties, root growth parameters and plant components. All statistical analyses were performed using SAS v9.1 (SAS Institute, Cary, NC). 3. Results 3.1. Soil chemical properties Vermicompost applications influenced soil chemical properties depending both on the type of vermicompost and the application amount (Table 2). Soil pH tended to increase in vermicompost treatments and was significantly different in the FDV40 and PSV40 treatments. NO3− and P2O5 were greater in the CMV40 treatment than in untreated control plots. Ca and Mg concentrations increased in the FDV40 and PSV40 treatments, respectively. Some correlations were found between soil chemical properties and root growth properties as follows: pH vs. yield (r = 0.51, P = 0.02), pH vs. root weight (r = 0.35, P = 0.001), pH vs. root rot disease (r = 0.57, P = 0.007), NO3− vs. yield (r = −0.48, P = 0.028). There were also correlations between soil properties and root mineral contents as follows: pH vs. Mn (r = −0.66, P = 0.001), pH vs. Zn (r = −0.57, P = 0.007), EC vs. K (r = 0.44, P = 0.05), EC vs. Mg (r = 0.64, P = 0.002), NO3− vs. Mn (r = 0.59, P = 0.005).
2.2. Soil sampling and analysis Soil samples were collected from 4 to 5 places in each plot and homogenised. Root debris was carefully removed, and soils were passed through a 2-mm mesh sieve for further analysis. The soil nitrate concentration was measured using an autoanalyser (AutoAnalyser 3, Bran +Luebbe, Germany). The available phosphate was determined using the Lancaster method, and the soil organic content was determined by the Tyurin method (RDA, 2002). Exchangeable cations were extracted with 1 N NH4OAc (pH 7.0) and measured using inductively coupled plasma-optical emission spectrometry (ICP-OES) (Integra XMP, GBC, Australia).
3.2. Plant growth and root contents The root yield was greater in the PSV40 treatment vs. control, and root rot incidence was significantly greater in the FWV40 treatment (Table 3). No significant correlation was found between yield and root rot disease (r = 0.33, P = 0.15). K and Mg in roots were significantly higher in the CMV40 treatment than in the control (Table 4). Significant correlations between root growth and plant mineral contents were as follows: root yield vs. Fe (r = −0.46, P = 0.04), root weight vs. Mg (r = −0.48, P = 0.03), root weight vs. Mn (r = −0.72, P = 0.0003), root rot vs. Zn (r = −0.59, P = 0.005).
2.3. Ginseng growth and root rot disease Ginseng roots were harvested on 12 October 2011 and root growth Table 1 Chemical characteristics of the experimental vermicomposts.
FWV CMV PSV
T-N (%)
P (%)
K (%)
Ca (%)
Mg (%)
Moisture (%)
1.3 0.8 1.0
0.5 0.3 0.1
0.2 0.6 0.1
5.3 1.5 1.7
0.2 0.6 1.4
35.0 51.0 34.0
3.3. Ginsenoside content The total ginsenoside content and levels of some ginsenosides, including Re, Rf, Rb1, Rc, Rg2 and Rd, varied among treatments
FWV, food waste vermicompost; CMV, cow manure vermicompost; PSV, paper sludge vermicompost. 459
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Table 2 Soil chemical properties resulting from vermicompost application.
Control FWV10 FWV40 CMV10 CMV40 PSV10 PSV40
PH (1:5)
EC (dS m−1)
OM (g kg−1)
NO3− (mg kg−1)
Av.P2O5 (mg kg−1)
K (cmol+ kg−1)
Ca (cmol+ kg−1)
Mg (cmol+ kg−1)
5.1b 5.5b 6.3a 5.4b 5.4b 5.4b 6.1a
1.0a 1.2a 1.0a 1.0a 1.6a 1.0a 1.5a
13.7b 14.5ab 17.0ab 14.3ab 17.2ab 13.6b 19.0a
64.0b 73.6ab 60.7b 52.1b 118.0a 60.1b 60.9b
54.0c 99.2bc 136.1ab 87.2bc 173.9a 81.9c 92.2bc
0.3a 0.3a 0.2a 0.3a 0.4a 0.3a 0.2a
2.8b 3.8b 5.8a 3.3b 4.2ab 3.1b 4.0b
1.0c 1.0c 1.1c 1.1c 1.5b 1.3bc 1.9a
Means of each parameter with different letters are significantly different. FWV, food waste vermicompost; CMV, cow manure vermicompost; PSV, paper sludge vermicompost. Different letters following values indicate significant difference. The subscripted number after the fertilizer name indicates the applied rate (g kg−1 soil).
nutrient that promotes root growth, considering the highest level of this nutrient was found in the PSV40 treatment. Xia et al. (2016) also reported a positive role of Mg in the growth of Panax notoginseng. Furthermore, a positive correlation between root weight and plant Mg content suggested that Mg might influence root growth. Besides its influence on soil chemistry, composted paper sludge plays a beneficial role in increasing water retention ability (Foley and Cooperband, 2002) and labile soil C and N volumes (Newman et al., 2005). Although the contents of humic and fulvic acids in vermicompost were not determined in the present study, vermicomposting increases the humification degree of humic and fulvic acids (Zhang et al., 2015). Humic acid promotes plant growth (Arancon et al., 2006; Canellas et al., 2002). It also improves soil microbial community structure and mycorrhizal colonization (Maji et al., 2017), in addition to the availability of other soil nutrients (Mehrizi et al., 2015).
Table 3 Root growth parameters and root rot disease incidence of ginseng.
Control FWV10 FWV40 CMV10 CMV40 PSV10 PSV40
Yield (t ha−1)
Root weight (g)
Survival (%)
Root rot (%)
1.5b 1.7ab 2.2ab 1.8ab 1.3b 1.9ab 2.6a
10.9b 12.5ab 15.3ab 12.5ab 10.2b 13.5ab 18.7a
76.2a 66.7a 85.7a 87.3a 68.3a 77.8a 81.0a
26.7bc 33.3b 50.0a 13.3c 43.3ab 40.0ab 43.3ab
Means of each parameter with different letters are significantly different. FWV, food waste vermicompost; CMV, cow manure vermicompost; PSV, paper sludge vermicompost. Different letters following values indicate significant difference. The subscripted number after the fertilizer name indicates the applied rate (g kg−1 soil).
4.2. Soil pH
(Table 5). Rf was 1.6 times greater in the PSV40 treatment than in the control. Root weight and yield were correlated with several individual ginsenosides (Table 6). Plant mineral content, including P, Fe and Mn levels, had multiple correlations with ginsenosides (Table 7). Some ginsenosides were correlated with soil chemical parameters as follows: EC vs. Rh2 (r = 0.48, P = 0.03), P2O4 vs. Rg3 (r = −0.45, P = 0.04). NO3− was correlated with Rb1 (r = −0.43, P = 0.04), Rg2 (r = 0.50, P = 0.02) and Rh2 (r = 0.66, P = 0.0001).
Interestingly, root growth was positively correlated with soil pH rather than the expected nutrient level. The high pH value in the PSV40 treatment partly explained the increased root yield in this treatment. Paddy fields often have low soil pH because of previous management history such as repeated fertilisation and anaerobic conditions. Vermicompost application might increase the pH of acidic soil because it tends to have a near neutral pH (Albanell et al., 1988). Furthermore, the negative correlation between NO3− and root yield could be partly explained by low soil pH because there is an inverse response of pH to NO3− input. A change in soil pH is also known to influence plant mineral content such as Mn and Zn. Soil pH can be negatively correlated with Mn and Fe (Farhoodi and Coventry, 2008). An increase in soil pH prevents Fe absorption (Olsen et al., 1981), but this phenomenon was not observed in our study.
4. Discussion 4.1. Paper sludge vermicompost and root growth Vermicompost's effect on root growth parameters varied with amount and type of vermicompost applied. The root yield was higher in the PSV40 treatment than in the untreated control. However, this difference could not be attributed to an increase in major nutrients such as NO3− and P2O5. NO3−correlated negatively with yield, and P2O5 showed no apparent correlation with yield. Mg is another candidate
4.3. Root growth and ginsenoside content The relationship of root growth to ginsenoside differed among
Table 4 Ginsenoside content in roots following vermicompost application.
Control FWV10 FWV40 CMV10 CMV40 PSV10 PSV40
Rg1
Re
Rf
Rb1
Rc
Rg2
Rh1
Rb2
Rd
Rg3
Rg5
Rh2
Total
3.7a 4.5a 4.1a 4.2a 3.7a 4.6a 4.8a
6.3ab 6.0ab 5.0b 6.9a 6.4ab 5.9ab 6.1ab
2.3b 2.6ab 2.6ab 3.3ab 3.2ab 3.1ab 3.7a
6.3ab 6.8ab 5.8ab 7.5a 4.8b 6.8ab 7.2ab
4.4a 4.4ab 3.6bc 4.5a 3.5c 3.9abc 4.7a
0.5ab 0.4ab 0.3b 0.6a 0.6a 0.5ab 0.5ab
0.1a 0.2a 0.2a 0.1a 0.1a 0.1a 0.1a
3.1a 3.0a 2.5a 3.2a 2.5a 2.9a 3.2a
0.9a 0.7abc 0.6bc 0.7abc 0.6c 0.7abc 0.9ab
0.1a 0.1a 0.1a 0.1a 0.2a 0.1a 0.1a
0.7a 1.1a 1.1a 1.4a 1.4a 1.3a 1.2a
0.4a 0.4a 0.3a 0.4a 0.4a 0.3a 0.4a
29.0a 30.3a 26.3a 32.9a 27.2a 30.2a 32.9a
Means of each parameter with different letters are significantly different. FWV, food waste vermicompost; CMV, cow manure vermicompost; PSV, paper sludge vermicompost. Different letters following values indicate significant difference. The subscripted number after the fertilizer name indicates the applied rate (g kg−1 soil). 460
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Table 5 Mineral content of roots following vermicompost application.
Control FWV10 FWV40 CMV10 CMV40 PSV10 PSV40
T-C (%)
T-N (%)
P (g kg−1)
K (g kg−1)
Ca (g kg−1)
Mg (g kg−1)
Na (g kg−1)
Fe (g kg−1)
Mn (mg kg−1)
Cu (mg kg−1)
Zn (mg kg−1)
42.8a 43.0a 42.9a 42.8a 42.3a 43.0a 41.9a
2.7a 2.6a 2.6a 2.6a 2.8a 2.7a 2.7a
1.3a 1.0a 1.0a 1.1a 1.3a 1.2a 1.2a
10.2b 10.0b 9.2b 9.5b 12.4a 9.4b 9.4b
3.1a 3.3a 3.1a 3.2a 3.2a 3.1a 3.3a
1.8bc 2.0bc 1.6c 1.8bc 2.2a 1.9ab 2.0ab
0.9a 0.9a 0.8a 0.8a 1.0a 0.9a 0.9a
0.2a 0.2a 0.2a 0.2a 0.2a 0.2a 0.2a
90.2a 53.9ab 38.1b 60.6ab 83.2a 43.5b 27.3b
14.1a 13.5a 13.7a 13.2a 14.2a 14.2a 14.3a
28.0a 21.4ab 20.9b 26.6ab 24.8ab 22.3ab 19.0b
Means of each parameter with different letters are significantly different. FWV, food waste vermicompost; CMV, cow manure vermicompost; PSV, paper sludge vermicompost. Different letters following values indicate significant difference. The subscripted number after the fertilizer name indicates the applied rate (g kg−1 soil). Table 6 Correlation coefficient between root parameters and ginsenosides.
Weight Yield Survival Root rot
Rg1
Re
Rf
Rb1
Rc
Rg2
Rh1
Rb2
Rd
Rg3
Rg5
Rh2
Total
−0.37 −0.46∗ −0.41 0.09
−0.35 −0.39 −0.23 0.09
−0.44∗ −0.45∗ −0.30 −0.09
−0.35 −0.38 −0.23 0.12
−0.39 −0.44∗ −0.32 0.05
−0.37 −0.24 0.13 0.01
−0.08 −0.20 −0.24 −0.01
−0.29 −0.29 −0.12 0.07
−0.34 −0.35 −0.24 0.03
0.03 −0.02 −0.01 −0.22
−0.34 −0.54∗∗ −0.55∗∗ −0.03
−0.19 −0.14 0.16 0.06
−0.39 −0.44* −0.28 0.08
Asterisks indicate significant correlations (∗ < 0.05;
∗∗
< 0.01).
Table 7 Correlation coefficient between root nutrient content and ginsenosides.
T-C T-N P K Ca Mg Na Mn Cu Fe Zn
Rg1
Re
Rf
Rb1
Rc
Rg2
Rh1
Rb2
Rd
Rg3
Rg5
Rh2
Total
−0.27 −0.18 −0.13 0.01 0.32 0.11 −0.01 −0.39 −0.16 0.59** −0.32
−0.23 0.24 0.42 0.27 0.32 0.28 0.36 −0.02 0.05 0.47* 0.09
−0.63 −0.05 0.08 0.16 0.21 0.25 0.10 −0.31 −0.11 0.40 −0.22
−0.32 −0.19 0.01 −0.22 0.19 −0.13 −0.18 −0.38 −0.23 0.39 −0.22
−0.24 −0.20 −0.06 −0.06 0.20 0.06 0.12 −0.11 −0.13 0.48* 0.00
−0.48 0.22 0.50* 0.18 0.10 0.32 0.25 −0.08 0.07 0.24 −0.04
−0.05 0.00 −0.06 −0.04 −0.01 −0.14 −0.10 −0.41 0.15 0.03 −0.49*
−0.41 −0.11 0.11 −0.10 0.17 0.00 −0.06 −0.22 −0.20 0.44* −0.09
−0.19 −0.09 0.10 −0.35 −0.10 −0.10 −0.12 −0.09 −0.16 0.14 −0.03
0.25 0.12 0.13 0.10 0.25 0.42 0.49* −0.32 0.22 0.32 −0.50
0.03 0.01 0.49* −0.01 0.33 0.03 0.10 −0.45* 0.40 0.18 −0.25
0.19 −0.13 −0.28 0.34 0.13 0.23 0.28 0.48* −0.35 0.41 0.40
−0.37 −0.04 0.13 −0.01 0.29 0.09 0.05 −0.33 −0.11 0.53 −0.19
Asterisks indicate significant correlations (* < 0.05; ** < 0.01).
4.4. Root Fe and ginsenoside content
vermicompost treatments. Individual ginsenosides and total ginsenoside may be affected differently by soil treatments such as nutrient supplementation (Lee and Mudge, 2013). Previous studies reported inconsistent fertilisation effects. Organic fertilisers had different effects on root growth and ginsenoside content depending on the type of fertilizer and its application dose (Park et al., 2015). Inorganic fertilisers either promoted both root growth and ginsenoside content (Xia et al., 2016), had no effect on either (Lee and Mudge, 2013), or had a positive effect on root growth and negative effect on ginsenoside content (Park et al., 1986). Reeleder et al. (2000) reported that increasing planting density caused reduced root weight but did not alter ginsenoside content, indicating an absence of competition between plant growth and ginsenoside production. However, in our study, the negative correlation between root yield and total ginsenoside content strongly suggests a trade-off between the two parameters. Ginsenosides are synthesised from isopentenyl pyrophosphate, which is biosynthesised via the mevalonic acid and methylerythritol phosphate pathways in plants (Dubey et al., 2003; Hampel et al., 2007). The trade-off between biomass and ginsenoside production is inconsistent and sometimes contradictory. Haukioja et al. (1998) reported that these two factors do not directly limit available nitrogen by competition with biomass production. In contrast, Massad et al. (2012) suggested that saponin production competes with photosynthesis for nitrogen resources.
Ginsenoside plays a role in biological tolerance of environmental stress (Devi et al., 2012). Saponin concentration is affected by abiotic factors (Szakiel et al., 2011), and fertilisation influences the secondary metabolite generation via changes in soil properties (Ibrahim et al., 2013). Fe in the roots was positively correlated with total ginsenoside, which suggests a mechanism of ginsenoside production. Zhang et al. (2013) reported that Fe in foliar application is transported more easily than Zn, Mg and C, and that Fe increases root yield and total ginsenoside content. Increased mineral content might activate a biosynthetic enzyme for ginsenoside (Zhang et al., 2013). Root yield was negatively correlated with both Fe and total ginsenoside content, which strongly indicates that increased Fe absorption may accelerate ginsenoside biosynthesis, although the mechanism remains poorly understood. Fe increased in the epidermal tissues of rusty rather than that of healthy tissue with contrasting results for total ginsenoside content (Rahman and Punja, 2005). In this case, increased Fe was due to chelation with phenolic compounds, and was related to defence response in plants. Fe also indirectly increases ginsenoside production by enhancing rusty root symptoms, which are supposedly associated with defence responses (Rahman and Punja, 2005).
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4.5. Root rot disease
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Zinc nutrition effect on the tolerance of wheat genotypes to Fusarium root-rot disease in a solution culture experiment. Soil Sci. Plant Nutr. 56, 234–243. Kim, G.S., Lee, S.E., Noh, H.J., Kwon, H., Lee, S.W., Kim, S.Y., Kim, Y.B., 2012. Effects of natural bioactive products on the growth and ginsenoside contents of Panax ginseng cultured in an aeroponic system. J. Ginseng Res. 36, 430–441. Lee, J., Mudge, K.W., 2013. Gypsum effects on plant growth, nutrients, ginsenosides, and their relationship in American ginseng. Hortic. Environ. Biotechnol. 54, 228–235. Lee, S.W., Park, J.M., Kim, G.S., Park, K.C., Jang, I.B., Lee, S.H., Kang, S.W., Cha, S.W., 2012. Comparison of growth characteristics and ginsenosides content of 6-year-old ginseng (Panax ginseng C.A. Meyer) by drainage class in paddy field. Kor. J. Med. Crop Sci. 20, 177–183. Maji, D., Misra, P., Singh, S., Kalra, A., 2017. Humic acid rich vermicompost promotes plant growth by improving microbial community structure of soil as well as root nodulation and mycorrhizal colonization in the roots of Pisum sativum. Appl. Soil Ecol. 110, 97–108. Massad, T.J., Dyer, L.A., Vega, C.G., 2012. Costs of defense and a test of the carbonnutrient balance and growth-differentiation balance hypotheses for two co-occurring classes of plant defense. PLoS One 7, e47554. Mehrizi, M.H., Sarcheshmehpour, M., Ebrahimi, Z., 2015. The effects of some humic substances and vermicompost on phosphorus transformation rate and forms in a calcareous soil. J. Soil Sci. Plant Nutr. 15, 249–260 2015. Newman, C.M., Rotenberg, D., Cooperband, L.R., 2005. Paper mill residuals and compost effects on particulate organic matter and related soil functions in a sandy soil. Soil Sci. 170, 788–801. Nicol, R.W., Traquair, J.A., Bernards, M.A., 2002. Ginsenosides as host resistance factors in American ginseng (Panax quinquefolius). Can. J. Bot. 80, 557–562. Olsen, R.A., Clark, R.B., Bennet, J.H., 1981. The enhancement of soil fertility by plant roots. Am. Sci. 69, 378–384. Park, H., Lee, M.K., Lee, C.H., 1986. Effect of nitrogen phosphorus and potassium on ginsenoside composition of Panax ginseng root grown with nutrient solution. J. Kor. Agric. Chem. Soc. 29, 78–82. Park, H.W., Mo, H.S., Jang, I.B., Yu, J., Lee, Y.S., Kim, Y.C., Park, K.C., Lee, E.H., Kim, K.H., Hyun, D.Y., 2015. Emergence rate and growth characteristics of ginseng affected by different types of organic matters in greenhouse of direct-sowing culture. Kor. J. Med. Crop Sci. 23, 27–36. Rahman, M., Punja, Z.K., 2005. Factors influencing development of root rot on ginseng caused by Cylindrocarpon destructans. Phytopathology 95, 1381–1390. Rahman, M., Punja, Z.K., 2006. Influence of iron on cylindrocarpon root rot development on ginseng. Phytopathology 96, 1179–1187. RDA, 2002. Methods of Soil and Plant Analysis. Rural Development Administration, Suwon, Korea. Reeleder, R.D., Capell, B., Hendel, J., Starratt, A., 2000. Influence of plant density on yield and ginsenoside levels of Panax quinquefolius L. J. Herbs Spices Med. Plants 7, 65–76. Santos, R.M., Fortes, G.A.C., Ferri, P.H., Santos, S.C., 2011. Braz. J. Pharmacogn. 21, 581–586.
Organic materials may promote pathogenic fungi growth by providing an organic substrate (Eo and Park, 2013). However, no difference was found in this regard between vermicompost treated ginseng and untreated controls. Incidence of root rot disease was positively correlated with soil pH which may, in turn, negatively influence Cylindrocarpon root rot development (Rahman and Punja, 2005). Therefore, increased pH might offset the promoting effects on the growth of pathogenic fungi caused by an increase in substrate input. Furthermore, vermicompost has a suppressive effect on pathogenic fungi (Ersahin et al., 2009) and increases production of antioxidants and some metabolites (Wang et al., 2010). Overall, vermicompost was beneficial to ginseng growth in this study because it increased nutrient content without accompanying damage by root rot disease. Increased production of some ginsenosides follows a pathogen attack, and these ginsenosides may have a suppressive effect on the pathogen (Nicol et al., 2002; Jiao et al., 2011). However, we found no correlation between root rot disease incidence and ginsenoside content, indicating that ginsenoside was only slightly involved in the defence mechanism against pathogens. Rahman and Punja (2006) reported that Fe stimulated Cylindrocarpon root rot, and that Fe enhanced total phenolic content. However, of all of the plant minerals tested, root rot disease was only negatively correlated with Zn. A similar trend was reported in Rhizoctonia root rot disease in wheat (Thongbai et al., 1993), and increase in Zn concentration had a positive effect on wheat tolerance to Fusarium root rot (Khoshgoftarmanesh et al., 2010). However, little information is available on root rot disease of ginseng and further studies are required on the role of Zn in the suppression of root rot disease. 5. Conclusion Root growth, ginsenoside content and root rot disease are three factors that should be taken into account during ginseng production, and they all may be affected by application of vermicomposts. Our results demonstrated that proper use of vermicomposts can promote ginseng yield without accompanying root loss caused by root rot disease. However, the incidence of root rot disease increased in the FWV40 treatment. Vermicompost applications increased soil pH, which was favourable for ginseng production in fields converted from paddies. A positive correlation between root yield and ginsenoside indicated a trade-off between the two parameters. Cultural methods are needed to maximise production of both parameters. Additionally, cultural control of individual ginsenoside content may be needed because of the demand for specific pharmacological effects. For example, ginsenoside Rf has a pharmacological effect on regulation of lipoprotein metabolism (Lee et al., 2012). Strong correlation between Fe and ginsenoside suggested involvement of Fe in the biosynthesis of ginsenoside. Further research is needed on the interactions between plant mineral content, ginsenoside and root growth. References Albanell, E., Plaixats, J., Cabrero, T., 1988. Chemical changes during vermicomposting (Eisenia fetida) of sheep manure mixed with cotton industrial wastes. Biol. Fertil. Soils 6, 266–269. Arancon, N.Q., Edwards, C.A., Lee, S., Byrne, R., 2006. Effects of humic acids from vermicomposts on plant growth. Eur. J. Soil Biol. 42, S65–S69. Atiyeh, R.M., Arancon, N.Q., Edwards, C.A., Metzger, J.D., 2002. The influence of earthworm-processed pig manure on the growth and productivity of marigolds. Bioresour. Technol. 81, 103–108. Attele, A.S., Wu, J.A., Yuan, C.S., 1999. Ginseng pharmacology: multiple constituents and multiple actions. Biochem. Pharmacol. 58, 1685–1693. Azarmi, R., Giglou, M.T., Taleshmikail, R.D., 2008. Influence of vermicompost on soil chemical and physical properties in tomato (Lycopersicum esculentum) field. Afr. J. Biotechnol. 7, 2397–2401. Baeg, I.H., So, S.H., 2013. The world ginseng market and the ginseng (Korea). J. Ginseng Res. 37, 1–7.
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Yang, M., Zhang, X., Xu, Y., Mei, X., Jiang, B., Liao, J., Yin, Z., Zheng, J., Zhao, Z., Fan, L., He, X., Zhu, Y., Zhu, S., 2015. Autotoxic ginsenosides in the rhizosphere contribute to the replant failure of Panax notoginseng. PLoS One 10, e0118555. Zhang, H., Yang, H., Wang, Y., Gao, Y., Zhang, L., 2013. The response of ginseng grown on farmland to foliar-applied iron, zinc, manganese and copper. Ind. Crops Prod. 45, 388–394. Zhang, J., Lv, B., Xing, M., Yang, J., 2015. Tracking the composition and transformation of humic and fulvic acids during vermicomposting of sewage sludge by elemental analysis and fluorescence excitation-emission matrix. Waste Manag. 39, 111–118.
Szakiel, A., Paczkowski, C., Henry, M., 2011. Influence of environmental abiotic factors on the content of saponins in plants. Phytochem. Rev. 10, 471–491. Thongbai, P., Graham, R.D., Neate, S.M., Webb, M.J., 1993. Interaction between zinc nutritional status of cereals and Rhizoctonia root rot severity. Plant Soil 153, 215–222. Wang, D., Shi, Q., Wang, X., Wei, M., Hu, J., Liu, J., Yang, F., 2010. Influence of cow manure vermicompost on the growth, metabolite contents, and antioxidant activities of Chinese cabbage (Brassica campestris ssp. Chinensis). Biol. Fertil. Soils 46, 689–696. Xia, P., Guo, H., Zhao, H., Jiao, J., Keyholos, M.K., Yan, X., Liu, Y., Liang, Z., 2016. Optimal fertilizer application for Panax notoginseng and effect of soil water on root rot disease and saponin contents. J. Ginseng Res. 40, 38–46.
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Journal of Environmental Management journal homepage: www.elsevier.com/locate/jenvman
Research article
Effect of vermicompost application on root growth and ginsenoside content of Panax ginseng
T
Jinu Eo∗, Kee-Choon Park National Institute of Agricultural Sciences, RDA, Wanju, 55365, Republic of Korea
A R T I C LE I N FO
A B S T R A C T
Keywords: Ginsenoside Paddy-converted field Panax ginseng Root rot disease Vermicompost
Vermicomposts are valuable by-products of organic wastes and can be used to improve soil environments in ginseng production. We compared the effects of food waste vermicompost (FWV), cow manure vermicompost (CMV) and paper sludge vermicompost (PSV) on several ginseng root production variables. Interactions between soil chemical properties, root growth, ginsenoside content and plant mineral content were also investigated. In the PSV treatment, the root yield increased by 40 t ha−1 compared to the untreated control. Nitrate concentration correlated negatively with root yield, and none of the vermicompost treatments differed significantly from the control in terms of root loss. Soil pH correlated positively with root weight, and total ginsenoside content did not vary among treatments, although some individual ginsenosides did differ among treatments. Root iron content correlated strongly with total ginsenoside content, and total ginsenoside content correlated negatively with root yield. Overall, our results showed that the root yield increase was not due to nutrient increase. Vermicompost was safe to use in relation to root rot disease, and it favourably elevated the pH of fields converted from rice paddies to ginseng production. Ginsenoside was not involved in defence mechanisms against root rot disease. Root iron content may have been involved in the metabolism of ginsenoside, and there was an apparent trade-off between ginsenoside content and root yield. Finally, vermicompost application altered resource allocation and soil chemical properties, which led to novel interactions between root parameters and components.
1. Introduction Panax ginseng, which is used as an herbal supplement, is cultured in Asia, Europe and North America (Baeg and So, 2013). Ginseng root production requires root growth and control of root rot disease. Root growth is influenced by soil properties such as nutrient content, pH and soil moisture (Lee and Mudge, 2013). Root rot disease has been reported as a major threat to ginseng and is primarily caused by fungal pathogens such as Cylindrocarpon destructans and Fusarium solani (Eo and Park, 2013). Damage caused by root rot disease is often most severe in replanted fields, and disease incidence can be reduced using cultural measures. Ginseng is commonly produced in fields converted from paddies because it is a good option for controlling root rot disease. Ginsenoside is a triterpenoidic saponin found in various parts of ginseng plants such as berries, roots and leaves (Chuang and Sheu, 1994). Ginsenoside is believed to have pharmacological properties such as antioxidant and anticarcinogenic effects on humans (Attele et al., 1999). In ginseng cultivation, ginsenosides influence ginseng yield through increased nutrient uptake and pathogen resistance. A trade-off
∗
between biomass and ginsenoside content can occur because ginseng plants redistribute available resources for multiple, competing purposes. Ginsenoside plays a defence role against pathogens, pests and plants (Nicol et al., 2002; Yang et al., 2015). Fungal infection promotes production of some forms of ginsenoside in ginseng plants (Jiao et al. 2011, 2015). Organic wastes are produced from industrial processing and stalk removal. For economic and environmental reasons, reusing these wastes benefits crop cultivation. Vermicompost uses these organic wastes and increases the quality of raw waste (Kaviraj, 2003). Vermicomposts, when applied to crops, promote plant growth by improving soil's nutritional and physical properties (Atiyeh et al., 2002; Azarmi et al., 2008). However, plants often show contrasting responses between nutrient content vs. growth and secondary metabolite production (Hofmann and Jahufer, 2011). Moreover, adding organic materials may negatively affect plant yield by promoting pathogenic fungi proliferation via substrate supply (Eo and Park, 2013). Studying root growth, ginsenoside content and root rot disease simultaneously can help us evaluate the benefits of vermicomposts.
Corresponding author. E-mail address: [email protected] (J. Eo).
https://doi.org/10.1016/j.jenvman.2018.12.101 Received 11 September 2018; Received in revised form 28 November 2018; Accepted 26 December 2018 0301-4797/ © 2018 Elsevier Ltd. All rights reserved.
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J. Eo, K.-C. Park
parameters were measured. Harvested roots were washed with tap water. Ten roots with undamaged body shape were weighed. Root rot disease was assessed for all roots by counting roots having brown spots larger than 3 mm in diameter.
Cultural methods have been developed to stabilise yield and ginsenoside content simultaneously (Park et al., 1986; Lee et al., 2012). Here, we tested three types of vermicompost produced from cow manure, food waste and paper sludge, respectively, to develop methods for vermicompost application in ginseng production. We tested the effects of these vermicomposts on root growth, ginsenoside content and root rot disease. Interactions among these parameters have been poorly studied, and environmental control of these interactions is important for maximising ginseng yield. We hypothesised that changes in soil properties by vermicomposts may alter ginseng root growth parameters as well as their interactions with each other and with their environment. We also investigated the correlation of plant mineral content with other parameters because mineral composition influences the level of secondary metabolites by altering degradation and biosynthesis of metabolites (Santos et al., 2011; Zhang et al., 2013).
2.4. Ginsenoside analysis The ginsenoside content was measured using the method of Kim et al. (2012). Ginseng root samples of 0.2 g were freeze-dried, powdered and extracted with 70% MeOH. The suspension was ultrasonicated for 30 min at 50 °C and then centrifuged for 15 min at 13,000 rpm. The supernatant was filtered through a Sep-Pak C18 cartridge (Waters Corp., Milford, MA, USA) and then through a 0.45 μL microfilter (Watman Mini-UniPrep Syringeless Filters, USA). The ginsenoside analysis was conducted using the LC-1100 system (Agilent, Waldbronn, Germany). Chromatographic separations were conducted on a Halo® RP - Amide column (4.6 × 150 mm, 2.7 μm at 50 °C). The mobile phase was established with an eluent (acetonitrile: deionised Water = 30: 70), and the flow rate was 0.5–0.8 mL min−1. UV detection was conducted at 203 nm, and the injected volume was 10 μL. Standard ginsenosides were purchased from a chemical company (ChromaDex Inc., Santa Ana, CA, USA).
2. Materials and methods 2.1. Experiment site Our experiment was conducted in Eumseong Province, Korea. The field was a former paddy which was converted in 2008 when watering ceased. Three compost types were tested: food waste vermicompost (FWV), cow manure vermicompost (CMV) and paper sludge vermicompost (PSV). They were made by composting with a mixture of two earthworm species, Eisenia fetida and Eisenia andrei. FWV was obtained from Hansol Agricultural Cooperative (Asan, Korea), whereas CMV and PSV were obtained from local manufacturers in Ulsan and Cheonan, respectively. The chemical content of each vermicompost is presented at Table 1. Two volumes of vermicompost, 10 and 40 t ha−1, were applied in November 2008. Untreated plots were used as controls. Three replicates of the experiment were established using a randomised block design. The area of each plot was 0.9 m × 3.6 m and one-year-old ginseng seedlings were transplanted at a rate of 35 plants m−2 on 17 March 2009. Rice straw was applied as mulch on the soil surface. Shading facilities were constructed from 23 March to 24 April 2009. Fungicides were applied to control leaf blight and anthracnose during the growing season.
2.5. Data analysis Differences among the treatments were analysed using an LSD test at P = 0.05 if a significant ANOVA result was found. Correlation coefficients were calculated between soil chemical properties, root growth parameters and plant components. All statistical analyses were performed using SAS v9.1 (SAS Institute, Cary, NC). 3. Results 3.1. Soil chemical properties Vermicompost applications influenced soil chemical properties depending both on the type of vermicompost and the application amount (Table 2). Soil pH tended to increase in vermicompost treatments and was significantly different in the FDV40 and PSV40 treatments. NO3− and P2O5 were greater in the CMV40 treatment than in untreated control plots. Ca and Mg concentrations increased in the FDV40 and PSV40 treatments, respectively. Some correlations were found between soil chemical properties and root growth properties as follows: pH vs. yield (r = 0.51, P = 0.02), pH vs. root weight (r = 0.35, P = 0.001), pH vs. root rot disease (r = 0.57, P = 0.007), NO3− vs. yield (r = −0.48, P = 0.028). There were also correlations between soil properties and root mineral contents as follows: pH vs. Mn (r = −0.66, P = 0.001), pH vs. Zn (r = −0.57, P = 0.007), EC vs. K (r = 0.44, P = 0.05), EC vs. Mg (r = 0.64, P = 0.002), NO3− vs. Mn (r = 0.59, P = 0.005).
2.2. Soil sampling and analysis Soil samples were collected from 4 to 5 places in each plot and homogenised. Root debris was carefully removed, and soils were passed through a 2-mm mesh sieve for further analysis. The soil nitrate concentration was measured using an autoanalyser (AutoAnalyser 3, Bran +Luebbe, Germany). The available phosphate was determined using the Lancaster method, and the soil organic content was determined by the Tyurin method (RDA, 2002). Exchangeable cations were extracted with 1 N NH4OAc (pH 7.0) and measured using inductively coupled plasma-optical emission spectrometry (ICP-OES) (Integra XMP, GBC, Australia).
3.2. Plant growth and root contents The root yield was greater in the PSV40 treatment vs. control, and root rot incidence was significantly greater in the FWV40 treatment (Table 3). No significant correlation was found between yield and root rot disease (r = 0.33, P = 0.15). K and Mg in roots were significantly higher in the CMV40 treatment than in the control (Table 4). Significant correlations between root growth and plant mineral contents were as follows: root yield vs. Fe (r = −0.46, P = 0.04), root weight vs. Mg (r = −0.48, P = 0.03), root weight vs. Mn (r = −0.72, P = 0.0003), root rot vs. Zn (r = −0.59, P = 0.005).
2.3. Ginseng growth and root rot disease Ginseng roots were harvested on 12 October 2011 and root growth Table 1 Chemical characteristics of the experimental vermicomposts.
FWV CMV PSV
T-N (%)
P (%)
K (%)
Ca (%)
Mg (%)
Moisture (%)
1.3 0.8 1.0
0.5 0.3 0.1
0.2 0.6 0.1
5.3 1.5 1.7
0.2 0.6 1.4
35.0 51.0 34.0
3.3. Ginsenoside content The total ginsenoside content and levels of some ginsenosides, including Re, Rf, Rb1, Rc, Rg2 and Rd, varied among treatments
FWV, food waste vermicompost; CMV, cow manure vermicompost; PSV, paper sludge vermicompost. 459
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Table 2 Soil chemical properties resulting from vermicompost application.
Control FWV10 FWV40 CMV10 CMV40 PSV10 PSV40
PH (1:5)
EC (dS m−1)
OM (g kg−1)
NO3− (mg kg−1)
Av.P2O5 (mg kg−1)
K (cmol+ kg−1)
Ca (cmol+ kg−1)
Mg (cmol+ kg−1)
5.1b 5.5b 6.3a 5.4b 5.4b 5.4b 6.1a
1.0a 1.2a 1.0a 1.0a 1.6a 1.0a 1.5a
13.7b 14.5ab 17.0ab 14.3ab 17.2ab 13.6b 19.0a
64.0b 73.6ab 60.7b 52.1b 118.0a 60.1b 60.9b
54.0c 99.2bc 136.1ab 87.2bc 173.9a 81.9c 92.2bc
0.3a 0.3a 0.2a 0.3a 0.4a 0.3a 0.2a
2.8b 3.8b 5.8a 3.3b 4.2ab 3.1b 4.0b
1.0c 1.0c 1.1c 1.1c 1.5b 1.3bc 1.9a
Means of each parameter with different letters are significantly different. FWV, food waste vermicompost; CMV, cow manure vermicompost; PSV, paper sludge vermicompost. Different letters following values indicate significant difference. The subscripted number after the fertilizer name indicates the applied rate (g kg−1 soil).
nutrient that promotes root growth, considering the highest level of this nutrient was found in the PSV40 treatment. Xia et al. (2016) also reported a positive role of Mg in the growth of Panax notoginseng. Furthermore, a positive correlation between root weight and plant Mg content suggested that Mg might influence root growth. Besides its influence on soil chemistry, composted paper sludge plays a beneficial role in increasing water retention ability (Foley and Cooperband, 2002) and labile soil C and N volumes (Newman et al., 2005). Although the contents of humic and fulvic acids in vermicompost were not determined in the present study, vermicomposting increases the humification degree of humic and fulvic acids (Zhang et al., 2015). Humic acid promotes plant growth (Arancon et al., 2006; Canellas et al., 2002). It also improves soil microbial community structure and mycorrhizal colonization (Maji et al., 2017), in addition to the availability of other soil nutrients (Mehrizi et al., 2015).
Table 3 Root growth parameters and root rot disease incidence of ginseng.
Control FWV10 FWV40 CMV10 CMV40 PSV10 PSV40
Yield (t ha−1)
Root weight (g)
Survival (%)
Root rot (%)
1.5b 1.7ab 2.2ab 1.8ab 1.3b 1.9ab 2.6a
10.9b 12.5ab 15.3ab 12.5ab 10.2b 13.5ab 18.7a
76.2a 66.7a 85.7a 87.3a 68.3a 77.8a 81.0a
26.7bc 33.3b 50.0a 13.3c 43.3ab 40.0ab 43.3ab
Means of each parameter with different letters are significantly different. FWV, food waste vermicompost; CMV, cow manure vermicompost; PSV, paper sludge vermicompost. Different letters following values indicate significant difference. The subscripted number after the fertilizer name indicates the applied rate (g kg−1 soil).
4.2. Soil pH
(Table 5). Rf was 1.6 times greater in the PSV40 treatment than in the control. Root weight and yield were correlated with several individual ginsenosides (Table 6). Plant mineral content, including P, Fe and Mn levels, had multiple correlations with ginsenosides (Table 7). Some ginsenosides were correlated with soil chemical parameters as follows: EC vs. Rh2 (r = 0.48, P = 0.03), P2O4 vs. Rg3 (r = −0.45, P = 0.04). NO3− was correlated with Rb1 (r = −0.43, P = 0.04), Rg2 (r = 0.50, P = 0.02) and Rh2 (r = 0.66, P = 0.0001).
Interestingly, root growth was positively correlated with soil pH rather than the expected nutrient level. The high pH value in the PSV40 treatment partly explained the increased root yield in this treatment. Paddy fields often have low soil pH because of previous management history such as repeated fertilisation and anaerobic conditions. Vermicompost application might increase the pH of acidic soil because it tends to have a near neutral pH (Albanell et al., 1988). Furthermore, the negative correlation between NO3− and root yield could be partly explained by low soil pH because there is an inverse response of pH to NO3− input. A change in soil pH is also known to influence plant mineral content such as Mn and Zn. Soil pH can be negatively correlated with Mn and Fe (Farhoodi and Coventry, 2008). An increase in soil pH prevents Fe absorption (Olsen et al., 1981), but this phenomenon was not observed in our study.
4. Discussion 4.1. Paper sludge vermicompost and root growth Vermicompost's effect on root growth parameters varied with amount and type of vermicompost applied. The root yield was higher in the PSV40 treatment than in the untreated control. However, this difference could not be attributed to an increase in major nutrients such as NO3− and P2O5. NO3−correlated negatively with yield, and P2O5 showed no apparent correlation with yield. Mg is another candidate
4.3. Root growth and ginsenoside content The relationship of root growth to ginsenoside differed among
Table 4 Ginsenoside content in roots following vermicompost application.
Control FWV10 FWV40 CMV10 CMV40 PSV10 PSV40
Rg1
Re
Rf
Rb1
Rc
Rg2
Rh1
Rb2
Rd
Rg3
Rg5
Rh2
Total
3.7a 4.5a 4.1a 4.2a 3.7a 4.6a 4.8a
6.3ab 6.0ab 5.0b 6.9a 6.4ab 5.9ab 6.1ab
2.3b 2.6ab 2.6ab 3.3ab 3.2ab 3.1ab 3.7a
6.3ab 6.8ab 5.8ab 7.5a 4.8b 6.8ab 7.2ab
4.4a 4.4ab 3.6bc 4.5a 3.5c 3.9abc 4.7a
0.5ab 0.4ab 0.3b 0.6a 0.6a 0.5ab 0.5ab
0.1a 0.2a 0.2a 0.1a 0.1a 0.1a 0.1a
3.1a 3.0a 2.5a 3.2a 2.5a 2.9a 3.2a
0.9a 0.7abc 0.6bc 0.7abc 0.6c 0.7abc 0.9ab
0.1a 0.1a 0.1a 0.1a 0.2a 0.1a 0.1a
0.7a 1.1a 1.1a 1.4a 1.4a 1.3a 1.2a
0.4a 0.4a 0.3a 0.4a 0.4a 0.3a 0.4a
29.0a 30.3a 26.3a 32.9a 27.2a 30.2a 32.9a
Means of each parameter with different letters are significantly different. FWV, food waste vermicompost; CMV, cow manure vermicompost; PSV, paper sludge vermicompost. Different letters following values indicate significant difference. The subscripted number after the fertilizer name indicates the applied rate (g kg−1 soil). 460
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Table 5 Mineral content of roots following vermicompost application.
Control FWV10 FWV40 CMV10 CMV40 PSV10 PSV40
T-C (%)
T-N (%)
P (g kg−1)
K (g kg−1)
Ca (g kg−1)
Mg (g kg−1)
Na (g kg−1)
Fe (g kg−1)
Mn (mg kg−1)
Cu (mg kg−1)
Zn (mg kg−1)
42.8a 43.0a 42.9a 42.8a 42.3a 43.0a 41.9a
2.7a 2.6a 2.6a 2.6a 2.8a 2.7a 2.7a
1.3a 1.0a 1.0a 1.1a 1.3a 1.2a 1.2a
10.2b 10.0b 9.2b 9.5b 12.4a 9.4b 9.4b
3.1a 3.3a 3.1a 3.2a 3.2a 3.1a 3.3a
1.8bc 2.0bc 1.6c 1.8bc 2.2a 1.9ab 2.0ab
0.9a 0.9a 0.8a 0.8a 1.0a 0.9a 0.9a
0.2a 0.2a 0.2a 0.2a 0.2a 0.2a 0.2a
90.2a 53.9ab 38.1b 60.6ab 83.2a 43.5b 27.3b
14.1a 13.5a 13.7a 13.2a 14.2a 14.2a 14.3a
28.0a 21.4ab 20.9b 26.6ab 24.8ab 22.3ab 19.0b
Means of each parameter with different letters are significantly different. FWV, food waste vermicompost; CMV, cow manure vermicompost; PSV, paper sludge vermicompost. Different letters following values indicate significant difference. The subscripted number after the fertilizer name indicates the applied rate (g kg−1 soil). Table 6 Correlation coefficient between root parameters and ginsenosides.
Weight Yield Survival Root rot
Rg1
Re
Rf
Rb1
Rc
Rg2
Rh1
Rb2
Rd
Rg3
Rg5
Rh2
Total
−0.37 −0.46∗ −0.41 0.09
−0.35 −0.39 −0.23 0.09
−0.44∗ −0.45∗ −0.30 −0.09
−0.35 −0.38 −0.23 0.12
−0.39 −0.44∗ −0.32 0.05
−0.37 −0.24 0.13 0.01
−0.08 −0.20 −0.24 −0.01
−0.29 −0.29 −0.12 0.07
−0.34 −0.35 −0.24 0.03
0.03 −0.02 −0.01 −0.22
−0.34 −0.54∗∗ −0.55∗∗ −0.03
−0.19 −0.14 0.16 0.06
−0.39 −0.44* −0.28 0.08
Asterisks indicate significant correlations (∗ < 0.05;
∗∗
< 0.01).
Table 7 Correlation coefficient between root nutrient content and ginsenosides.
T-C T-N P K Ca Mg Na Mn Cu Fe Zn
Rg1
Re
Rf
Rb1
Rc
Rg2
Rh1
Rb2
Rd
Rg3
Rg5
Rh2
Total
−0.27 −0.18 −0.13 0.01 0.32 0.11 −0.01 −0.39 −0.16 0.59** −0.32
−0.23 0.24 0.42 0.27 0.32 0.28 0.36 −0.02 0.05 0.47* 0.09
−0.63 −0.05 0.08 0.16 0.21 0.25 0.10 −0.31 −0.11 0.40 −0.22
−0.32 −0.19 0.01 −0.22 0.19 −0.13 −0.18 −0.38 −0.23 0.39 −0.22
−0.24 −0.20 −0.06 −0.06 0.20 0.06 0.12 −0.11 −0.13 0.48* 0.00
−0.48 0.22 0.50* 0.18 0.10 0.32 0.25 −0.08 0.07 0.24 −0.04
−0.05 0.00 −0.06 −0.04 −0.01 −0.14 −0.10 −0.41 0.15 0.03 −0.49*
−0.41 −0.11 0.11 −0.10 0.17 0.00 −0.06 −0.22 −0.20 0.44* −0.09
−0.19 −0.09 0.10 −0.35 −0.10 −0.10 −0.12 −0.09 −0.16 0.14 −0.03
0.25 0.12 0.13 0.10 0.25 0.42 0.49* −0.32 0.22 0.32 −0.50
0.03 0.01 0.49* −0.01 0.33 0.03 0.10 −0.45* 0.40 0.18 −0.25
0.19 −0.13 −0.28 0.34 0.13 0.23 0.28 0.48* −0.35 0.41 0.40
−0.37 −0.04 0.13 −0.01 0.29 0.09 0.05 −0.33 −0.11 0.53 −0.19
Asterisks indicate significant correlations (* < 0.05; ** < 0.01).
4.4. Root Fe and ginsenoside content
vermicompost treatments. Individual ginsenosides and total ginsenoside may be affected differently by soil treatments such as nutrient supplementation (Lee and Mudge, 2013). Previous studies reported inconsistent fertilisation effects. Organic fertilisers had different effects on root growth and ginsenoside content depending on the type of fertilizer and its application dose (Park et al., 2015). Inorganic fertilisers either promoted both root growth and ginsenoside content (Xia et al., 2016), had no effect on either (Lee and Mudge, 2013), or had a positive effect on root growth and negative effect on ginsenoside content (Park et al., 1986). Reeleder et al. (2000) reported that increasing planting density caused reduced root weight but did not alter ginsenoside content, indicating an absence of competition between plant growth and ginsenoside production. However, in our study, the negative correlation between root yield and total ginsenoside content strongly suggests a trade-off between the two parameters. Ginsenosides are synthesised from isopentenyl pyrophosphate, which is biosynthesised via the mevalonic acid and methylerythritol phosphate pathways in plants (Dubey et al., 2003; Hampel et al., 2007). The trade-off between biomass and ginsenoside production is inconsistent and sometimes contradictory. Haukioja et al. (1998) reported that these two factors do not directly limit available nitrogen by competition with biomass production. In contrast, Massad et al. (2012) suggested that saponin production competes with photosynthesis for nitrogen resources.
Ginsenoside plays a role in biological tolerance of environmental stress (Devi et al., 2012). Saponin concentration is affected by abiotic factors (Szakiel et al., 2011), and fertilisation influences the secondary metabolite generation via changes in soil properties (Ibrahim et al., 2013). Fe in the roots was positively correlated with total ginsenoside, which suggests a mechanism of ginsenoside production. Zhang et al. (2013) reported that Fe in foliar application is transported more easily than Zn, Mg and C, and that Fe increases root yield and total ginsenoside content. Increased mineral content might activate a biosynthetic enzyme for ginsenoside (Zhang et al., 2013). Root yield was negatively correlated with both Fe and total ginsenoside content, which strongly indicates that increased Fe absorption may accelerate ginsenoside biosynthesis, although the mechanism remains poorly understood. Fe increased in the epidermal tissues of rusty rather than that of healthy tissue with contrasting results for total ginsenoside content (Rahman and Punja, 2005). In this case, increased Fe was due to chelation with phenolic compounds, and was related to defence response in plants. Fe also indirectly increases ginsenoside production by enhancing rusty root symptoms, which are supposedly associated with defence responses (Rahman and Punja, 2005).
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4.5. Root rot disease
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Soil Ecol. 71, 58–64. Ersahin, Y.S., Haktanir, K., Yanar, Y., 2009. Vermicompost suppresses Rhizoctonia solani Kuhn in cucumber seedlings. J. Plant Dis. Prot. 116, 182–188. Farhoodi, A., Coventry, D.R., 2008. Field crop responses to lime in the mid-north region of South Australia. Field Crops Res. 108, 45–53. Foley, B.J., Cooperband, L.R., 2002. Paper mill residuals and compost effects on soil carbon and physical properties. J. Environ. Qual. 31, 2086–2095. Hampel, D., Swatski, A., Mosandl, A., Wust, M., 2007. Biosynthesis of monoterpenes and norisoprenoids in raspberry fruits (Rubus idaeus L.): the role of cytosolic mevalonate and plastidial methylerythritol phosphate pathway. J. Agric. Food Chem. 55, 9296–9304. Haukioja, E., Ossipov, V., Koricheva, J., Honkanen, T., Larsson, S., Lempa, K., 1998. Biosynthetic origin of carbon-based secondary compounds: cause of variable responses of woody plants to fertilization? Chemoecology 8, 133–139. Hofmann, R.W., Jahufer, M.Z.Z., 2011. Tradeoff between biomass and flavonoid accumulation in white clover reflects contrasting plant strategies. PLoS One 6, e18949. Ibrahim, M.H., Jaafar, H.Z.E., Karimi, E., Ghasemzadeh, A., 2013. Impact of organic and inorganic fertilization on the phytochemical and antioxidant activity of kacip fatimah (Labisia pumila Benth). Molecules 18, 10973–10988. Jiao, X.L., Bi, W., Li, M., Luo, Y., Gao, W.W., 2011. Dynamic response of ginsenosides in American ginseng to root fungal pathogens. Plant Soil 339, 317–327. Jiao, X., Lu, X., Chen, A.J., Luo, Y., Hao, J.J., Gao, W., 2015. Effects of Fusarium solani and F. oxysporum infection on the metabolism of ginsenosides in American ginseng roots. Molecules 20, 10535–10552. Kaviraj, S.S., 2003. Municipal solid waste management through vermicomposting employing exotic and local species of earthworms. Bioresour. Technol. 90, 169–173. Khoshgoftarmanesh, A.H., Kabiri, S., Shariatmadari, H., Sharifnabi, B., Schulin, R., 2010. 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Humic acid rich vermicompost promotes plant growth by improving microbial community structure of soil as well as root nodulation and mycorrhizal colonization in the roots of Pisum sativum. Appl. Soil Ecol. 110, 97–108. Massad, T.J., Dyer, L.A., Vega, C.G., 2012. Costs of defense and a test of the carbonnutrient balance and growth-differentiation balance hypotheses for two co-occurring classes of plant defense. PLoS One 7, e47554. Mehrizi, M.H., Sarcheshmehpour, M., Ebrahimi, Z., 2015. The effects of some humic substances and vermicompost on phosphorus transformation rate and forms in a calcareous soil. J. Soil Sci. Plant Nutr. 15, 249–260 2015. Newman, C.M., Rotenberg, D., Cooperband, L.R., 2005. Paper mill residuals and compost effects on particulate organic matter and related soil functions in a sandy soil. Soil Sci. 170, 788–801. Nicol, R.W., Traquair, J.A., Bernards, M.A., 2002. Ginsenosides as host resistance factors in American ginseng (Panax quinquefolius). Can. J. Bot. 80, 557–562. Olsen, R.A., Clark, R.B., Bennet, J.H., 1981. The enhancement of soil fertility by plant roots. Am. Sci. 69, 378–384. Park, H., Lee, M.K., Lee, C.H., 1986. Effect of nitrogen phosphorus and potassium on ginsenoside composition of Panax ginseng root grown with nutrient solution. J. Kor. Agric. Chem. Soc. 29, 78–82. Park, H.W., Mo, H.S., Jang, I.B., Yu, J., Lee, Y.S., Kim, Y.C., Park, K.C., Lee, E.H., Kim, K.H., Hyun, D.Y., 2015. Emergence rate and growth characteristics of ginseng affected by different types of organic matters in greenhouse of direct-sowing culture. Kor. J. Med. Crop Sci. 23, 27–36. Rahman, M., Punja, Z.K., 2005. Factors influencing development of root rot on ginseng caused by Cylindrocarpon destructans. Phytopathology 95, 1381–1390. Rahman, M., Punja, Z.K., 2006. Influence of iron on cylindrocarpon root rot development on ginseng. Phytopathology 96, 1179–1187. RDA, 2002. Methods of Soil and Plant Analysis. 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Organic materials may promote pathogenic fungi growth by providing an organic substrate (Eo and Park, 2013). However, no difference was found in this regard between vermicompost treated ginseng and untreated controls. Incidence of root rot disease was positively correlated with soil pH which may, in turn, negatively influence Cylindrocarpon root rot development (Rahman and Punja, 2005). Therefore, increased pH might offset the promoting effects on the growth of pathogenic fungi caused by an increase in substrate input. Furthermore, vermicompost has a suppressive effect on pathogenic fungi (Ersahin et al., 2009) and increases production of antioxidants and some metabolites (Wang et al., 2010). Overall, vermicompost was beneficial to ginseng growth in this study because it increased nutrient content without accompanying damage by root rot disease. Increased production of some ginsenosides follows a pathogen attack, and these ginsenosides may have a suppressive effect on the pathogen (Nicol et al., 2002; Jiao et al., 2011). However, we found no correlation between root rot disease incidence and ginsenoside content, indicating that ginsenoside was only slightly involved in the defence mechanism against pathogens. Rahman and Punja (2006) reported that Fe stimulated Cylindrocarpon root rot, and that Fe enhanced total phenolic content. However, of all of the plant minerals tested, root rot disease was only negatively correlated with Zn. A similar trend was reported in Rhizoctonia root rot disease in wheat (Thongbai et al., 1993), and increase in Zn concentration had a positive effect on wheat tolerance to Fusarium root rot (Khoshgoftarmanesh et al., 2010). However, little information is available on root rot disease of ginseng and further studies are required on the role of Zn in the suppression of root rot disease. 5. Conclusion Root growth, ginsenoside content and root rot disease are three factors that should be taken into account during ginseng production, and they all may be affected by application of vermicomposts. Our results demonstrated that proper use of vermicomposts can promote ginseng yield without accompanying root loss caused by root rot disease. However, the incidence of root rot disease increased in the FWV40 treatment. Vermicompost applications increased soil pH, which was favourable for ginseng production in fields converted from paddies. A positive correlation between root yield and ginsenoside indicated a trade-off between the two parameters. Cultural methods are needed to maximise production of both parameters. Additionally, cultural control of individual ginsenoside content may be needed because of the demand for specific pharmacological effects. For example, ginsenoside Rf has a pharmacological effect on regulation of lipoprotein metabolism (Lee et al., 2012). Strong correlation between Fe and ginsenoside suggested involvement of Fe in the biosynthesis of ginsenoside. Further research is needed on the interactions between plant mineral content, ginsenoside and root growth. References Albanell, E., Plaixats, J., Cabrero, T., 1988. Chemical changes during vermicomposting (Eisenia fetida) of sheep manure mixed with cotton industrial wastes. Biol. Fertil. Soils 6, 266–269. Arancon, N.Q., Edwards, C.A., Lee, S., Byrne, R., 2006. Effects of humic acids from vermicomposts on plant growth. Eur. J. Soil Biol. 42, S65–S69. Atiyeh, R.M., Arancon, N.Q., Edwards, C.A., Metzger, J.D., 2002. The influence of earthworm-processed pig manure on the growth and productivity of marigolds. Bioresour. Technol. 81, 103–108. Attele, A.S., Wu, J.A., Yuan, C.S., 1999. Ginseng pharmacology: multiple constituents and multiple actions. Biochem. Pharmacol. 58, 1685–1693. Azarmi, R., Giglou, M.T., Taleshmikail, R.D., 2008. Influence of vermicompost on soil chemical and physical properties in tomato (Lycopersicum esculentum) field. Afr. J. Biotechnol. 7, 2397–2401. Baeg, I.H., So, S.H., 2013. The world ginseng market and the ginseng (Korea). J. Ginseng Res. 37, 1–7.
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