Growth after Transplanting and Seedling Quality of Veronica nakaiana and Veronica kiusiana var. glabrifolia as Influenced by Number of Cells in Plug Tray, Medium Composition, and Fertilization Level
Article information
Abstract
Background and objective
This study was conducted to investigate the growth after transplanting and seedling quality of Veronica nakaiana and V. kiusiana var. glabrifolia according to number of cells in plug tray, medium composition, and fertilization level in plug seedling production.
Methods
The seeds of V. nakaiana and V. kiusiana var. glabrifolia were sown according to number of cells in plug tray (50, 105, 162, 200, and 288-cell) and medium composition (mixtures of peat moss and perlite at ratios of 100:0, 80:20, 60:40, 40:60, 20:80, and 0:100). And, after sowing the V. kiusiana var. glabrifolia seeds, they were treated with different fertilizer levels (Hyponex 0, 0.78, 1.56, 3.12, and 6.24 g/tray) during the seedling period.
Results
The seedling growth of V. nakaiana was more effective in plug tray of 50-cell than in the other plug trays, and there was no difference in growth after transplanting between 50 and 105-cell treatments. And, the growth of the seedlings was best in media mixed with peat moss and perlite at ratio of 100:0 and 80:20. In V. kiusiana var. glabrifolia, plug tray of 105-cell was best for seedling growth and plant growth after transplanting in pots. And, the seedling growth was the best in media mixed with peat moss and perlite at ratios of 80:20 and 60:40 compared to other media. The seedling growth was better in Hyponex treatments of 3.12 g/tray than in control and 6.24 g/tray treatments.
Conclusion
The sowing in plug trays of 105-cell filled with a medium mixed with peat moss and perlite at a ratio of 80:20 was most suitable for the seedling growth of V. nakaiana and V. kiusiana var. glabrifolia. In V. kiusiana var. glabrifolia, the treatment of Hyponex at a total of 3.12 g/tray during the seedling period after sowing was most effective for the growth of seedling.
Introduction
Native plants growing in Korea have adapted to the environmental conditions of the Korean Peninsula with the distinct four seasons, and have characteristics that allow them to grow well in their surrounding environments, without disrupting the surrounding ecosystem (Kim, 2003; Ryu, 2004). Veronica is a genus in the Scrophulariaceae family, comprising about 450 species worldwide (Albach et al., 2004). In Korea, there are 23 species of native Veronica, including V. nakaiana, V. kiusiana var. glabrifolia, V. pusanensis, V. pyrethrina, and others (Korea National Arboretum, 2024). V. nakaiana is a perennial herbaceous plant classified as a phytogeographical specific plant species of grade IV, and a plant species subject to export approval. It is a Korean endemic and rare plant that grows on Ulleungdo Island (Cho et al., 2013; Korean National Arboretum, 2021), has irregularly sawtooth shape on leaf margin, and blooms with light blue flowers in June and July, making it a valuable ornamental plant (Kwon et al., 2020; Korea National Arboretum, 2024).
V. kiusiana var. glabrifolia is known to be distributed in the north region of Jirisan Mountain, and is a perennial herbaceous plant that grows in mountainous areas, grows to a height of over one meter, and its flowers bloom blue in July and August, making it highly ornamental (Oh et al., 2020). To develop these highly ornamental native plants for garden, it is necessary to establish a mass propagation system that can produce high-quality seedlings.
Recently, to produce large quantities of uniform and high-quality seedlings efficiently, plug seedling production has been widely used for medicinal crops, vegetables, and herbaceous flowering plants. In plug seedling production, the seedling growth is influenced by the number of cells of the plug tray, medium composition, fertilization management, seedling period, and seedling environment (Roger and Koranski, 1997; Nam et al., 2003; Jang et al., 2022; Choi et al., 2024). In red pepper and medicinal crops such as Astragalus membranaceus, the number of cells of the plug tray was found to be more effective for seedling growth in larger plug trays compared to smaller ones, and the seedling period was extended according to the number of cells (Shin et al., 2000; Jeong et al., 2020). Also, for herbaceous flowering plants like Coleus blumei and Lythrum salicaria, seedlings grown in 72 and 162-cell plug trays were superior in terms of root length, plant height, number of leaves, fresh weight, and dry weight, compared to those grown in plug trays with more than 200 cells (Nam et al., 2003; Jang et al., 2022).
The medium for raising seedling must be able to maintain the available water required by the crops, retain the necessary nutrients, and ensure the smooth air permeability between the roots and the media, and support the plants. To maintain the available water content and air permeability of the medium, different types of substrates are mixed, or the mixing ratio is adjusted (Choi et al., 1997; Shin and Jeong, 2000; Cho et al., 2003). Choi et al. (1997) found that a medium mixed with 50:50 ratio of peat moss and perlite was better for seedling growth compared to a medium mixed with peat moss and vermiculite in plug seedling production of red pepper, as it had lower water holding capacity, but better air permeability. On the other hand, seedlings of Abelmoschus esculentus died in media with a higher ratio of peat moss than perlite because the water content is too high, so a medium mixed with 1:2 ratio of peat moss and perlite was most suitable for seedling growth(Lee et al., 2022). In the case of Gerbera, chlorosis appeared at 10 days after transplanting when grown in perlite alone, causing the seedlings to wither, which was attributed to the low moisture holding ability of the perlite (Cho et al., 2003). The mixing ratio of peat moss and perlite for optimal seedling growth varies, depending on the plant species.
In plug seedling production, the fertilization levels greatly affect the seedling growth. For Elsholtzia byeonsanensis, Amsonia elliptica, and E. angustifolia, the seedling growth significantly increased in a treatment of 1,000 mg·L−1 Hyponex, while lower concentrations inhibited growth (Lee et al., 2021; Lee et al., 2022; Lee et al., 2024). Also, seedlings of V. pusanensis and V. pyrethrina treated with liquid fertilizer (Peters professional) showed higher growth rates compared to the control group (Kwon et al., 2021; Oh et al., 2022).
Until now, research on the propagation and cultivation of V. nakaiana and V. kiusiana var. glabrifolia has been conducted on the germination temperature, shading conditions for growth, and cutting conditions (Song et al., 2019; Kwon et al., 2020; Song et al., 2022), but research to establish a mass propagation system using seeds has not previously been conducted. Therefore, this study aimed to establish a mass propagation system for V. nakaiana and V. kiusiana var. glabrifolia by investigating the seedling growth according to number of cells in plug tray, medium composition, and fertilization concentration in plug seedling production.
Research Methods
Plant materials
The seeds of V. nakaiana and V. kiusiana var. glabrifolia used in this study were provided by the Division of Gardening Plant Resources, Korea National Arboretum. The seeds were sown and raised in a plastic film greenhouse (660 m2) of the Mokpo National University Farm. The daily day and night mean temperature and relative humidity in greenhouse during the experimental period (April 23 – October 3) are shown in Fig. 1.
Seedling growth of V. nakaiana according to number of cells in plug tray and medium composition
To investigate the seedling growth of V. nakaiana according to number of cells in plug tray, 50-cell (73 mL per cell), 105-cell (30 mL per cell), 162-cell (15 mL per cell), 200-cell (10 mL per cell), and 288-cell (5 mL per cell) plug trays (28 cm × 54 cm, Bumnong Co., Ltd., Jeongeup, Korea) were used. After filling the plug trays with horticultural substrate (Biosangto® Heungnong Co., Ltd., Seosan, Korea), one seed was sown per cell on April 29, and three trays were used per treatment. After sowing, the cultivation management was carried out according to practice, and the seedling growth, such as plant height, leaf length and width, number of leaves, and fresh and dry weight of shoots and roots, was investigated 50 days after sowing. The seedlings grown by cell size were transplanted into 15 cm diameter plastic pots (2 L) containing horticultural substrate in 7 replicates at 50 days after sowing. And, the plant height, number of leaves, fresh and dry weight of shoot and root, and number of lateral branches were investigated at 115 days after transplanting.
To investigate the seedling growth of V. nakaiana according to the medium composition, 105-cell plug trays were filled with a mixture of peat moss (Lithuanian Peatmoss, Klasmann-Deilmann GmbH, Germany) and perlite (Parat No.3, 1–3 mm in diameter, Kyungdongone Co., Ltd, Korea) at ratios of 100:0, 80:20, 60:40, 40:60, 20:80, and 0:100 (v/v). One seed was sown per cell on April 29, and three trays were used per treatment. The seedling growth was investigated at 75 days after sowing.
Seedling growth of V. kiusiana var. glabrifolia according to number of cells in plug tray, medium composition, and fertilization level
To investigate the seedling growth of V. kiusiana var. glabrifolia according to number of cells in plug tray, the same plug trays and horticultural substrate were used as in experiment of V. nakaiana. One seed was sown per cell on April 22, and three trays were used per treatment. The seedling growth was investigated at 50 days after sowing. And then, in the same methods as in experiment of V. nakaiana, the seedlings were transplanted into 15 cm pots, and the growth of plants was investigated at 90 days after transplanting.
To investigate the seedling growth according to the medium composition, 105-cell plug trays were filled with the same media and ratios as in the experiment of V. nakaiana. One seed were sown per cell on April 26, and three trays were used per treatment. The seedling growth was investigated at 50 days after sowing.
To investigate the seedling growth according to the fertilization level, 105-cell plug trays were filled with a mixture of peat moss and perlite at ratio of 60:40 (v/v). One seed was sown per cell on April 27, and three trays were used per treatment. Fertilizer was treated with Hyponex (Professional N:P:K = 20:20:20, HYPONeX JAPAN Ltd., Osaka, Japan) at levels of 0, 0.8, 1.6, 3.2, and 6.4 g per tray during seedling period. It was drenched on media three times with 400mL per tray at 2-week intervals from 14 days after sowing, and the EC of the solutions by treatments were 0.08, 0.64, 1.07. 1.86, and 2.85 dS·m−1, respectively. The seedling growth was investigated at 50 days after sowing.
Statistical analysis
For statistical analysis, a one-way analysis of variance was performed on the research data on the seedling growth using IBM SPSS (Version 22.0 software, IBM Corp., USA). The means between all treatments were compared using Duncan’s multiple range test.
Results
Seedling growth of V. nakaiana according to number of cells in plug tray and medium composition
The results of investigating the seedling growth at 50 days after sowing V. nakaiana according to number of cells in plug tray showed that the larger the cell size, the better the seedling growth. In the 50-cell plug trays, the plant height was 9.3 cm, leaf length was 4.8 cm, leaf width was 3.9 cm, the number of leaves was 9.1, and the fresh weight of shoot was 21.4 g, which was better than the other treatments (Table 1). Also, the differences in dry weight of the shoot and fresh and dry weight of root were not statistically significant between the 50 and 105-cell treatments, but they were heavier in dry weight of root than the other treatments (Fig. 2).

Effect of different plug tray cell number on seedling growth of Veronica nakaiana at 50 days after sowing

Seedling growth of Veronica nakaiana according to number of cells in plug tray at 50 days after sowing.
The results of investigating the plant growth at 115 days after transplanting the seedlings grown by cell number showed that the plant height was 18.0–19.6 cm in the 50- 200-cell treatments, which was not statistically significant, and it was shortest at 16.2 cm in the 288-cell treatment (Table 2). The number of leaves, fresh weight of shoot and root, and dry weight of shoot were suppressed as the cell size decreased, and there were no significant differences between the 50 and 105-cell treatments (Fig. 3). The number of lateral branches were high at 9.2 in the 50-cell treatments, and low at 5.2–5.4 in the 200 and 288-cell treatments. In this way, when the seedlings grown in 50 and 105-cell plug trays were transplanted in pots, plant growth was more effective compared with other treatments. However, considering the economic aspect, it was judged that sowing seeds in 105-cell rather than 50-cell plug tray would be more efficient not only for seedling growth but also for subsequent plant growth after transplanting.

Shoot and root growth at 115 days after transplanting of seedling of Veronica nakaiana grown in different plug tray cell number

Growth response of shoot at 115 days after transplanting of seedling of Veronica nakaiana grown in different plug tray cell size.
According to the composition of peat moss and perlite, V. nakaiana seeds were sown, and the seedling growth was observed after at 75 days. Overall, the higher the mixing ratio of perlite, the more the growth was inhibited (Table 3). In the media mixed with peat moss and perlite at ratios of 100:0, 80:20, and 60:40, the plant height, leaf length, and leaf width increased compared to the media mixed with peat moss and perlite at ratios of 0:100, and the fresh weight of shoot and root and dry weight of root were most effective in the treatments of 100:0 and 80:20 (Fig. 4 A). Also, the root balls were well-formed in the treatments of 100:0, 80:20, and 60:40, but in treatments of 20:80 and 0:100, root balls were broken (Fig. 4B). Therefore, it was concluded that using media of peat moss and perlite mixed at ratios of 100:0 or 80:20 would be most effective for seedling growth of V. nakaiana.

Effect of different media composition on seedling growth of Veronica nakaiana at 75 days after sowing
Seedling growth of V. kiusiana var. glabrifolia according to number of cells in plug tray, medium composition, and fertilization level
The seedling growth of V. kiusiana var. glabrifolia was investigated at 50 days after sowing according to number of cells in plug tray. The leaf length and fresh weight of shoot were better in 50 and 105-cell treatments than in 162, 200, and 288-cell treatments (Table 4). The plant height was longer in the 105-cell treatment (6.4 cm) than in the other treatments (5.0–5.5 cm), and the fresh weight of root was also heavier at 1.8 g compared to the 50, 162, and 288-cell treatments (Fig. 5). However, there was no significant difference in the number of leaves and dry weight of root in 50, 105, 162, and 200-cell treatments except for 288-cell treatment. Therefore, it was concluded that using the 105-cell plug tray for seedlings growth of V. kiusiana var. glabrifolia would be effective.

Effect of different plug tray cell number on seedling growth of Veronica kiusiana var. glabrifolia at 50 days after sowing

Seedling growth of Veronica kiusiana var. glabrifolia according to plug tray cell number at 50 days after sowing.
The growth was observed 90 d after sowing according to the number of cells in plug tray. Overall, the seedlings raised in the 50 and 105-cell showed better growth in plant length at 86.6 and 76.0 cm, inflorescence length at 32.4 and 30.4 cm, number of inflorescences at 8.0 and 7.8, and number of lateral branches at 7.4 and 5.4, respectively, compared to the seedlings grown in the 200 and 288-cell treatments (Table 5). Except for the plant height and leaf length and width, the seedlings grown in the 162-cell treatment showed suppressed growth in inflorescence length, number of inflorescences, and number of lateral branches compared to the 50 and 105-cell treatments. And, except for the flowering date, there was no statistical difference in the growth of shoots and inflorescences of seedlings grown in 50 and 105 cells after transplantation. The seedling grown in trays with larger cell sizes flowered faster, and the seedlings grown in 50-cell flowered the earliest on September 2 (Fig. 6). Therefore, considering the plant growth and cultivation space, it was determined that transplanting of seedling grown in 105-cell plug tray would be the most effective in V. kiusiana var. glabrifolia.

Shoot growth and flowering response at 90 days after transplanting of seedling of Veronica kiusiana var. glabrifolia grown in different plug tray cell number

Shoot growth and flowering by number of cells in plug tray at 90 days after transplanting of Veronica kiusiana var. glabrifolia.
According to the composition of peat moss and perlite, seedling growth of V. kiusiana var. glabrifolia was observed at 50 days after sowing. Overall, the seedling growth was inhibited in the treatments with a mixing ratio of perlite above 80 % (20:80 and 0:100). The 100:0 treatment with 100% peat moss showed a decrease in leaf length, number of leaves, and fresh and dry weight of shoot and root compared to the mixing media at ratios of 80:20 and 60:40 (Table 6). Also, number of leaves were better in the mixing media of 80:20 and 60:40 than in medium of 40:60 (Fig. 7). There was no statistical difference in the growth of seedlings grown in media of 80:20 and 60:40. Therefore, it was concluded that using a media mixed with peat moss and perlite at ratios of 80:20 or 60:40 would be most effective for seedling growth of V. kiusiana var. glabrifolia.

Effect of different media composition on seedling growth of Veronica kiusiana var. glabrifolia at 50 days after sowing

Seedling growth of Veronica kiusiana var. glabrifolia according to media composition at 50 days after sowing.
After sowing V. kiusiana var. glabrifolia seeds in a 105-cell plug tray, Hyponex (N:P:K = 20:20:20) was applied according to the levels, and the seedling growth was the poorest in control (Table 7). The treatment with the highest fertilization level of 6.24 g Hyponex inhibited the plant length, leaf length and width, fresh weight of shoot and root, and dry weight of shoot compared to the treatments with 3.12 g (Fig. 8). The fresh weight of the shoot was heavier in the 3.12 g treatment compared to the 0.78 and 1.56 g treatments, but there was no significant difference in the other growth parameters. Therefore, it was concluded that applying 3.12 g of Hyponex per plug tray during the seedling period would be the most effective for the seedling growth of V. kiusiana var. glabrifolia.

Effect of different fertilization level on seedling growth of Veronica kiusiana var. glabrifolia at 50 days after sowing
Discussion
Seedling growth according to number of cells in plug tray
In plug seedling production, the number of cells in plug tray affects the seedling growth, and Astragalus membranaceus showed better growth in 128-cell plug tray compared to 200 and 288-cell plug trays (Jeong et al., 2020). In the case of Allium thunbergii for. rheophytum and A. pseudojaponicum, growth indicators such as plant height, number of leaves, and shoot and root biomass, were higher in the 50-cell than in the 72–200-cell (Park et al., 2023). Also, in the raising seedling of Lythrum salicaria and Elsholtzia byeonsanensis, the larger the cell size of plug tray, the better the growth (Jang et al., 2022; Lee et al., 2022). These results indicate that the large cell sizes of plug tray were effective for the growth of shoots and roots because the supply of nutrients increased as the volume of root zone and media increased compared small cell sizes of plug trays (Lee et al., 2021; Jang et al., 2022; Park et al., 2023).
In addition, the appropriate nursery period in plug seedling production varies depending on the type of plant (Shin et al., 2000; Kim et al., 2001). The coleus and celosia were most suitable for transplantation after 8 weeks and 4 weeks, respectively, when the plant height was 5–7 cm and the number of leaves was 5–7 (Nam et al., 2003). When the V. nakaiana and V. kiusiana var. glabrifolia were raised in 105-cell of plug tray for 50 days, the plant height was 6.4–7.7 cm and the number of leaves was about 6. Therefore, in the V. nakaiana and V. kiusiana var. glabrifolia, it was determined that raising seedling for about 50 days was the most suitable.
In this study, even in the plug seedling production of V. nakaiana and V. kiusiana var. glabrifolia, seedling growth was better in the 50 and 105-cell than in the 200 and 288-cell of plug trays, and even after transplanting, seedling grown in 50 and 105-cell showed better growth. It was determined that this was because the 50 and 105-cell with large cell volumes contained a large amount of medium and were sufficiently supplied with nutrients, which promoted the growth of shoots and roots.
Seedling growth according to the medium composition
The peat moss, which is widely used as a medium in plug seedling production, has a good water holding capacity of 55 %, but has the disadvantage of poor air permeability and drainage. Perlite has good air permeability due to its porosity, but poor moisture retention (Bilderback et al., 1982; Wilson, 1985; Shim et al., 2016; Kim and Yoo, 2024). The media for plug seedling production should have conditions such as appropriate air permeability and moisture and nutrients retention for seedling growth (Kumar et al., 2022), so it is common to mix 2 or 3 types of media. Therefore, the seedling growth is greatly influenced by the types and mixing ratios of the media.
In the plug seedling production of hot pepper 'Nokwang', the treatments of mixed media with cocopeat and perlite at a ratio of 60:40 or peat moss and perlite at a ratio 80:20 showed the highest fresh and dry weight of shoot. On the other hand, the higher the mixing ratio of perlite, the higher the air porosity and the lower moisture content of media, which reduces the amount of nutrients and water that the plants can absorb, resulting in poor seedling growth (Choi et al., 2006). In the case of V. pusanensis and V. pyrethrina, seedling growth was better in medium mixed with peat moss and perlite at a ratio of 4:1 than in that at a ratio of 1:1. This result indicated that the seedling growth was better because the medium mixed with 4:1 had higher water holding capacity of 80.3% compared to the medium mixed with 1:1 (64.7%) (Kwon et al., 2021; Oh et al., 2022). In this study, the seedling growths of V. nakaiana and V. kiusiana var. glabrifolia were good in a medium mixed with peat moss and perlite at a ratio of 80:20 which had high water holding capacity, whereas the seedling growth was poor in a medium mixed with peat moss and perlite at ratios of 20:80 and 0:100. Therefore, it was determined that the water holding capacity of the medium had a greatest influence on seedling growth in the plug seedling production of V. nakaiana and V. kiusiana var. glabrifolia.
Seedling growth according to fertilization level
Fertilization not only supplies nutrients to plants, but also affects plant growth by promoting microbial activity and physical properties in the soil (Thirukumaran and Parkinson, 2002; Choi et al., 2008). The main components of Hyponex fertilizer used in this experiment are nitrogen, phosphorus, and potassium. Nitrogen is a component of amino acids, proteins, nucleic acids, and chlorophyll in plants, and if the amount of fertilization is low, the growth and yield of crops as well as the chlorophyll content decrease (Bennett, 1993; Lee et al., 2004). Phosphorus is a component of phospholipids, nucleic acids, phosphoproteins, and ATP, and is a component that is highly required during the seedling period. If it is deficient, root development is poor, lower leaves wilt, and growth is inhibited (Penningsfeld, 1972; Bennett, 1993; Shin et al., 2000). Also, potassium is involved in the opening and closing of stomata, cell elongation, ATP synthesis, and carbohydrate and protein synthesis, and it is known that when it is deficient, plant height and fresh weight decrease (Holcomb and White, 1974; Marschner, 1995). During the seedling period, fertilization plays an important role in the growth of young seedlings by providing nutrients. In raising seedling of Chinese cabbage, fresh weight was the heaviest when 250 mg·L− nitrogen was applied as fertilizer, and it was reported that fresh weight decreased at low or high fertilizer concentrations (Kim et al., 2019). In Astragalus membranaceus, the fresh weight and dry weight of seedlings were the best at an EC level of 2.0 dS·m−1, but growth decreased at an EC level of 2.5 dS·m−1 or higher (Jeong et al., 2020). In this study, seedling growth of V. kiusiana var. glabrifolia was poorer in the treatment with 6.24 g Hyponex than in treatments with 0.78–3.13 g Hyponex per plug tray. These results were because the fertilization above the appropriate concentration required for seedling growth inhibited root growth as the salt concentration in the medium increased which lowered the osmotic pressure of the roots and thus decreased the amount of water absorption (Jeong et al., 2020; Oh et al., 2022).
Also, in a study on V. pusanensis, it was reported that treatment three times with 1,000 mg·L−1 Peters Professional fertilizer (N-K-P 20-20-20, ICL Professional Horticulture, USA) was more effective in the plant height, root length, fresh and dry weight of root than control or treatment with 2,000 mg·L−1. However, in the V. pyrethrina, although it was found that treatment with Peters Professional fertilizer was more effective for the seedling growth than the control, there was no difference in growth between treatments with 500 and 2,000 mg·L−1 (Kwon et al., 2021). Likewise, it was found that plants belonging to the same genus Veronica also had different fertilizer concentrations suitable for seedling growth during seedling period. Therefore, it is necessary to determine the level of fertilization suitable for seedling growth depending on the plant species. In this study, it was found that treatment with 6.24 g Hyponex per plug tray inhibited the seedling growth due to the high salinity concentration of the medium, whereas treatment with 3.12 g Hyponex three times during the seedling period was the most effective for seedling growth.
Conclusion
Veronica nakaiana is a perennial herbaceous plant that grows natively on Ulleungdo Island as Korean endemic plant, while V. kiusiana var. glabrifolia is a perennial herbaceous plant that grows natively in the mountainous regions north of Jirisan Mountain. These native plants have high ornamental value, so in order to develop them for garden, a mass propagation system that can produce high-quality seedlings must be established. The seedling growth of V. nakaiana was best when grown in a 50-cell plug tray, and there was no difference in plant growth after transplanting in pots seedling raised in 50 and 105-cell plug trays. The V. kiusiana var. glabrifolia showed the best seedling growth in a 105-cell plug tray, and even after transplanting in pot, the plant growth was better in seedling raised in a 105-cell plug tray than in seedlings raised in other cell number. Therefore, raising the V. nakaiana and V. kiusiana var. glabrifolia in a 105-cell plug tray was the most effective for seedling production, as well as for plant growth after transplanting.
Among the media used in plug seedling production, perlite offers good air permeability and drainage, but has the disadvantage of low water holding capacity, while peat moss offers high water holding capacity, but poor air permeability. Therefore, they are often used in combination to complement each other's disadvantages. In this study, the seedling growth of V. nakaiana and V. kiusiana var. glabrifolia was better in media with a higher ratio of peat moss than perlite. The seedling growth of V. nakaiana was more effective in media mixed with peat moss and perlite at ratios of 100:0 and 80:20, while seedling growth of V. kiusiana var. glabrifolia was the best in media mixed with peat moss and perlite at ratios of 80:20 and 60:40. These results suggest that the media with high water holding capacity rather than air permeability and drainage would be more positive for the seedling growth of V. nakaiana and V. kiusiana var. glabrifolia in plug seedling production.
In plug seedling production, fertilization is often supplied in the method of foliar spray, soil drench, and sub-irrigation with water soluble compound fertilizer. In this study, when Hyponex (N-P-K 20-20-20) was applied with soil drench method at 6.24 g per plug tray during seedling period, the seedling growth of V. kiusiana var. glabrifolia was inhibited. This was determined that the fertilization of high concentration increased the salt concentration of the medium, inhibiting shoot and root growth. On the other hand, the applying 0.78–3.12 g of Hyponex showed better seedling growth than the control and 6.24 g treatments, but fresh weight of shoot was heavier in the 3.12 g treatment compared to the 0.78 and 1.56 g treatments. Therefore, it was concluded that applying a 3.12 g Hyponex per plug tray during the seedling period was the most effective for seedling growth of V. kiusiana var. glabrifolia.
Notes
This study was conducted with the support of the Korea National Arboretum, as part of “Development of Breeding Models for Native Garden Plants in the New Climate Regime (KNA1-5-1-24-1)”. And, the English translation of this paper was supported by the Industry-Academic Cooperation Foundation of Mokpo National University.