Codonopsis lanceolata belonging to Campanulaceae, is a perennial plant that widely distributed in East Asia. This plant is cultivated in number of places in Korea, and its root is used for traditional medicinal (Ichikawa et al., 2009). The root extract of C. lanceolata cultivated in Korea contained saponin, vitamin B1 and B2, inulin etc that has been found to reduce the fatigue, blood pressure, cough, etc. (Moon, 1984).

The previous study demonstrated that the higher yield of C. lanceolata was observed from the transplanting culture system than the direct seedling method (Kim and Lee, 1979), and in the case of transplanted C. lanceolata, root length and root diameter play an essential role for the plant better growth and development, and thereby, production has increased remarkedly (Kim, 1985). As the hypertrophy growth of the underground part was much better with the air content of the soil (Russell, 1973), and the cultivation of C. lanceolata was suitable in the sandy soil that content a lot of humus (Lee, 1991).

Recently, the interest in the secondary metabolites has attained scientists concern of the main medicinal plants due to the development of various health functional food. C. lanceolata has reported several clinical trials earlier from which the extracts of C. lanceolata was used to explore the pharmacological efficacy of C. lanceolata roots (Kim et al., 2013; Song et al., 2012). Ichikawa et al. (2009) separated seven kinds of 3, 28-bidesmosidic triterpenoid saponin from Korean C. lanceolata root. Thus, C. lanceolata root extracts are expected not only by the possibility of health foods of various types but also by being possible to develop medicines through separation, purification of the extract. However, a sustainable supply is necessary to use it as raw materials of health foods and medicines, but the studies on this issue have been grossly overlooked (Cha et al., 2005).

Recently, fertilizer application has gained to the plant scientists attention to increase the production of many medicinal plants (Arab et al., 2015; Liu et al., 2014; Lu et al., 2013). Nitrogen is well-known fertilizer that is used to promote production, partitioning and accumulation of dry matter in crop plant (Wang et al., 2008). In addition, the effects of phosphorus and potassium fertilizers has been reported earlier in many medicinal plants (Lu et al., 2013; De La Rosa et al., 2001). However, no reports has been published to explore the effects of N, P, K on the growth characteristics of C. lanceolata.

Therefore, this study was performed to investigate the effects of nitrogen, phosphorus, and potassium fertilizers application on the growth, yield and mineral contents of C. lanceolata and to obtain the basic data for the proper fertilization for increasing the yield of C. lanceolata.

Materials & Methods

Plant growth condition and fertilizers application

The seeds of C. lanceolata were collected from Jeju and planted on October, 2013. In Oct. 2014, the 1 year old C. lanceolata roots (length ; 6 ~ 8 cm, diameter ; 0.5 ~ 0.8 cm, fresh weight ; 4 ~ 8 g) were harvested from Jeju as experimental materials. And in April 2015, The roots were grown in a pot (Wagner) packed with soil (4 kg) in the Woosong Information University. Temperature and humidity during the test period were automatically recorded every day for 30 minutes using automatic recording system (temperature TR-72, Ondotori, Japan: TR-71, humidity) in the 1 m height of the ground and the results of the investigation showed the means of 20 replicates (Fig. 1).

For treatment, fertilizers application were maintained per pot as nitrogen: active phosphoric acid: potassium = 6 g: 7 g: 3 g as a standard, a non fertilizer group (T0), P+K group (T1), N+K group (T2), N+P group (T3) and N+P+K group (T4), with 20 replicates each treatment.

Soil analysis and data collection

For soil analysis, the surface soil was collected and then dried it under shade condition. Soil pH, organic substances, active phosphoric acid, exchangeable salts were measured using ion electrode method, tyurin method, Lancaster method and 1N-NH₄OAc method respectively (NIAST, 2000).

In early September 2015, the morphological characteristics such as plant height, leaf characteristics, number of branches and internode length was investigated. At the end of September, the fresh weight, root length, root diameter and number of lateral roots were investigated. Other cultivation was managed in accordance with the standard cultivation method in the Rural Development Administration.

Analysis of inorganic components

The sample was incinerated at 600˚C for 12 hours and then decomposed by wet combustion method according to previously described method (Woo and Ryoo, 1983) with minor modification. Then the sample was made its quantity fixed with deionized distilled water to test the liquid. After adding 8 ml of concentrated nitric acid to 500 mg of the roots of C. lanceolata, the solution was heated with low temperature at first and then gradually increased heating temperature to decompose it. Decomposed solution was chilled when the solution become white and transparent, and then added distilled water to the solution and adjusted to 100 ml, and then filtered it to make the remained liquid as the sample. The quantity of each mineral content was examined by ICP (Inductively Coupled Plasma, 3300DV, PerkinElmer Optima, USA). The condition of analysis was maintained in the following manner; plasma 15 l/min for the gas flow rate, 0.5 l/min for the auxiliary, 0.8 l/min for the nebulizer, 1,300 watts for the RF power, 1.0 ml/min for the flow rate, 18.48 rpm for the speed, 1.0 ml/min for the sample flow rate, 30 sec for the sample flush time, 4.0 ml/min for the sample flush rate, and 30sec for the delay time.

Statistical analysis

Using SAS program (SAS, 9.2, Institute Inc, USA), statistical analysis was conducted by Duncan’s multiple range test (p = 0.05).

Results & Discussion

Effects of NPK and their interactions on growth characteristics of C. lanceolata

Physicochemical properties of the soil that used in this study are described in Table 1. The pH of testing soil was 5.7 as acidity, and organic matter content was 1.5%, active phosphoric acid 125 mg·kg. Exchangeable Ca: K: Mg: Na = 3.78 : 1.26 : 0.23 : 0.27 so that Mg was a little deficient state.

Plant height was significantly influenced by changes in NPK fertilization treatments (Table 2). In particular, the highest value (266.8 cm) of plant height character was obtained from the N+P+K group. The foliage growth of plant was also significantly influenced by the various treatment. However, the highest leaf width (4.9 cm) was found from P+K group compared to non fertilizer group while the longest leaf length (8.9 cm) was obtained from the N+P+K group. No significant differences (7.2 ~ 8.2 cm) were observed from the other treatment. Stem diameter was in the range of 4.5 ~ 4.7 cm and there were no significance differences among the fertilizer treatments although stem diameter has been found to be increased towards all fertilizers application. Previous results revealed that plant growth characters including plant height were significantly affected by the application various NPK fertilizers and their interactions in Nigella sativa L. (Khalid et al., 2015). It was also evident that both plant height and number of branches per plant were significantly increased in the application of NPK fertilizer in comparison to untreated control in two cultivars of Hibiscus sabdariffa L. (Abbas et al., 2011).

The highest number of branches (30.8) were obtained from the N+P+K group and the lowest number of branches (21.8) was observed from the P+K group. For the number of nodes, the plant length and a similar trend, by the fertilization process as vigorous growth of ground part, it was able to see that the number of nodes was increased, and the highest number of nodes (29.8) was observed from the N+P+K group.

Regardless of fertilization, the growth of internode became vine after node 5, and showed a rapid elongation of the internodes. The internode growth of C. lanceolata distributed in Korea, exhibited that the internode converted into vine after 5?6 node without any regional differences (Kim et al., 1998). The reported results was consistent with the results obtained from the present study suggesting that it was the key feature of C. lanceolata growth. However, the longest internode showed slightly difference depending on the type of fertilization. In addition, the highest elongation was observed from the node ranges from 8 ~ 13, but the growth of the top-internode tended to decrease remarkedly.

As a result, the results of this study was thought to be due to the temperature lowering of the growth in the latter part (Fig. 2). Chlorophyll content showed a high content in the range of 42.8 to 46.6 in all fertilization treatments, except for non fertilizer group and P+K group (T1). Previous study reported that nitrogen plays an important roles in plant growth and development. Therefore, nitrogen induces the essential constituent of enzymes, hormones, nucleic acids, etc. that promotes the various metabolism, voracious absorption and assimilation of nutrients (Ingestad & Agren, 1992; Lee et al., 2004; Vitousek et al., 2002). The results obtained from the present study showed that nitrogen treated group exhibited a pronounced growth of the ground part of C. lanceolata plant compared to other fertilizers group.

Effects of NPK and their interactions on root characteristics of C. lanceolata

The results of the present study observed that the root characteristics of the C. lanceolata depends on the fertilization quantity. The details results are shown in Table 3.

The root length was found to be significantly prolonged (25.7 cm) in the N+P+K group (T4) by the fertilization process compared to the non fertilizer (19.5 cm) group (T0). The root diameter also showed a similar trend to the root length, but N+P group (T3) and N+P+K group (T4) showed good results as 2.4 cm and 2.5 cm respectively. The fresh weight of roots were heavier (57.0 g) in the N+P+K group (T4) than other fertilization treatments.

In particular, the yield was shown to increase by about 2 times or more in the fertilization group than the non fertilizer group (T0). So, it revealed that the fertilization application especially for three elements of fertilizer, was undoubtedly crucial to increase production. Chang (1988) found that fertilization of 3 fertilizer elements is good for C. lanceolata by the same amount as 6 kg each for the production of root, but the result of this experiment, the better for the enlargement of the roots was to keep a little difference among the amount of three elements fertilizer as indicated were different. In the case of Platycodon grandiflorum that belongs to Campanulaceae such as C. lanceolata, was reasonable to approximately 10 kg fertilization per nitrogen, phosphorus and potassium in 10a that have been reported earlier (Choi, 1984) and the differences in the amount of fertilizer were found prominently in the hypertrophic growth of C. lanceolata and P. grandiflorum roots. The number of lateral roots (25.4) were observed most vigorously in N+P+K group (T4), compared to other treatments. Though, the number of lateral roots in other treatments had no significance in the range of 10.1 to 19.0.

Effects of NPK fertilization on the inorganic components content in the roots of Codonopsis lanceolata

The application of NPK fertilization had an adverse effects on the inorganic component contents of the root of C. lanceolata (Table 4).

If a macro element content of the roots, whereas a certain trend were not visible, in accordance with the difference between the fertilizer quantity, it was seen with the highest content for Na, Mg, P and Ca in N+P group (T3), and the N+P+K group (T4) showed a little less or a similar amount compared to the control. K exhibited the lowest content of potassium in the N+P group (T3). The micro elements content could also not see a certain trend in accordance with the difference in the fertilization quantity, and Mn and Fe have shown a high content each N+P+K group (T4) and the N+P group (T3), and Cu and Zn showed a higher content than other fertilization treatments in N+K group (T2) as 9.592 ppm, 22.57 ppm. However, Al was shown the highest result of the non fertilizer group (T0) so that it showed that the absorption of the fertilizer content of the N, P, K was suppressed.

From the above results, the content of Na, Mg, Cu and Al, from P+K group (T1), P from N+K group (T2) Mn from N+P group (T3) and Ca, Fe and Zn from the N+P+K group (T4) showed less amount of roots inorganic components than the other fertilizer treatment. Nitrogen, phosphorus or potassium deficiency was observed in the root growth of the C. lanceolata. It was considered as a factor that have a significant impact on the absorption of minerals in the soil. Therefore, it was determined that it needed a review of fertilization conditions, such as fertilizer quantity, soil and the kinds of various fertilizers for the elongation growth of C. lanceolata roots.

적 요