Eun A Kim’s scientific contributions

In the present study, we aimed to establish an efficient cultivation method for Tillandsia ionantha, which is commonly known as an air plant and is distributed as an ornamental succulent. This species was cultivated using non-substrate cultivation methods in a controlled environment, and the influence of various light spectra on its growth was investigated. The light-emitting diode (LED) light sources used included red (630 nm), green (520 nm), blue (450 nm), purple phyto-LED (450 nm, 650 nm, and far-red wavelengths), warm white (3000 K), natural white (4100 K), and cool white (6500 K) lights. The results showed that shoot length, root length, and leaf width significantly increased under monochromatic blue LED light, highlighting its effectiveness in promoting plant size. In contrast, root and leaf numbers were most effectively enhanced under cool white LED light, highlighting the suitability of broad-spectrum light for balanced root and leaf development. Biomass analysis revealed a growth imbalance between the shoot and root parts, with root biomass being the highest under warm white and cool white LED lights. Red LED light increased relative water content in shoots, indicating its potential for enhancing water retention. Additionally, the external quality of T. ionantha, evaluated using the Commission Internationale de l’Éclairage Lab (CIELAB) color space values, revealed significant changes in leaf coloration under various light spectra. The highest L * value was observed under the natural white LED treatment, whereas the a * and b * parameters varied significantly depending on the light spectra. These findings underscore the importance of light spectrum selection in optimizing T. ionantha various parameters and suggest that a combination of monochromatic and broad-spectrum light can be used complementarily for balanced growth and external quality. This study provides foundational data for the stable cultivation of epiphytic plant species in a controlled environment facility, supporting their broader application in the ornamental plant industry and indoor horticultural projects.

Betula platyphylla var. japonica, a member of the Betulaceae family, is a temperate landscape tree species with significant industrial value. This study investigated the effects of short-term dry-cold treatment periods that ranged from 0 to 60 days on the germination success of B. platyphylla var. japonica seeds and their post-germination growth and physiological characteristics. The short-term dry-cold treatment periods were 0 (control), 15, 30, 45, and 60 days. The results revealed that seeds subjected to a 30-day dry-cold treatment period exhibited the highest germination percentage, seedling survival rate, and germination energy, whereas relatively longer dry-cold treatment periods significantly decreased these parameters. Furthermore, the control without any dry-cold treatment exhibited a more pronounced decrease in these parameters. In contrast, the 15-day dry-cold treatment period was observed to be most beneficial in regard to enhancing the size and biomass of B. platyphylla var. japonica seedlings. Analysis of the remote sensing vegetation indices and chlorophyll fluorescence responses used to assess the physiological characteristics of seedlings indicated that a dry-cold treatment period of 0-15 days was the most appropriate. Therefore, when the primary objective is to maximize germination success and seedling survival rates, a 30-day dry-cold treatment period is optimal. Conversely, if the goal is to enhance rapid seedling growth and improve physiological characteristics, a 15-day short-term dry-cold treatment period is the most suitable. These findings offer valuable guidance for selecting appropriate short-term dry-cold treatment periods to maximize germination success, post-germination growth, and physiological performance of B. platyphylla var. japonica seeds.

Background and objective: This study aimed to investigate the effects of different types and concentrations of exogenous auxins on growth and rooting ability of Philodendron hederaceum var. oxycardium stem cuttings. Methods: Auxins used included indole acetic acid (IAA) at concentrations of 80, 160, and 320 mg⋅L-1, and 3-indolebutyric acid (IBA) and 1-naphthylacetic acid (NAA) at concentrations of 250, 500, and 1000 mg⋅L-1, respectively. Results: The application of auxins significantly improved the mean survival rate to 97.4%, compared to 91.4% in the control. The mean rooting rate also increased with auxin treatments, to 94.5% compared to 85.4% in the control. Additionally, shoot length, width, and both fresh and dry weights peaked at an IAA concentration of 320 mg⋅L-1, while leaf length and width were optimal at an IAA concentration of 160 mg⋅L-1. In contrast, the best results for root length and biomass, both fresh and dry weights, were observed with an IBA concentration of 250 mg⋅L-1. The Commission Internationale de l'Eclairage Lab (CIELAB) color space analysis showed that the control had higher L * (lightness) and b * (yellowness) values, indicating a lower ornamental value. Conclusion: The findings confirm that auxins effectively enhance the stem-cutting propagation of P. hederaceum var. oxycardium, regardless of type and concentration. For optimal shoot growth, an IAA concentration of 320 mg⋅L-1 is recommended, while an IBA concentration of 250 mg⋅L-1 is most effective for root growth.

Background: Salvia miltiorrhiza Bunge, an important medicinal crop, is documented in China's oldest pharmacopoeia, Shennong Bencaojing. However, research on the effects of light quality on its growth and photochemical responses is limited. Methods and Results: This study utilized T5 light-emitting diode (LED) bars with red (630 ㎚), green (520 ㎚), blue (450 ㎚), purple phyto (450 ㎚, 650 ㎚, and far-red), warm white (3000 K), natural white (4100 K), and cool white (6500 K) lights. The results indicated that white LEDs enhanced the shoot growth, chlorophyll content (SPAD units) and root number of S. miltiorrhizamore effectively than monochromatic LEDs and purple phyto-LEDs. Far-red wavelengths, approximately 17.6% of which are included in the purple phyto-LEDs, have been suggested to influence root length positively. Biomass was heavier under white LEDs, suggesting the importance of including the full spectrum of wavelengths within the photosynthetically active radiation range. White LEDs provided superior growth and photochemical efficiency, with slight variations based on the types of white light. Although green LED alone had negative effects, green wavelengths may be more crucial than far-red wavelengths when included in a composite spectrum. Conclusions: S. miltiorrhiza exhibited optimal growth and photochemical responses under white LED lights. Although green LED light alone has negative effects, green wavelengths within a composite spectrum may play a more important role than far-red wavelengths. However, further research is required to confirm these findings and fully understand the specific contributions of each wavelength.

This study investigates the influence of different light qualities, including red, green, blue, purple, and white lights, on the growth, physiological activity, and ornamental characteristics of two Coleus cultivars. Emphasizing the importance of leveraging phenotypic plasticity in plants within controlled environments, using light quality is a practice prevalent in the ornamental industry. The research explores the varied responses of two Coleus cultivars to distinct light spectra. The key findings reveal the efficacy of red light in enhancing shoot and leaf parameters in C. ‘Highway Ruby’, while red and green light exhibit comparable effects on shoot width and leaf dimensions in C. ‘Wizard Jade’. White light-emitting diodes (LEDs), particularly with color temperatures of 4100 K and 6500 K, promote root length growth in the respective cultivars. Moreover, chlorophyll content and remote sensing vegetation indices, including chlorophyll content (SPAD units), the normalized difference vegetation index (NDVI), the modified chlorophyll absorption ratio index (MCARI), and the photochemical reflectance index (PRI), along with the chlorophyll fluorescence, were significantly affected by light qualities, with distinct responses observed between the cultivars. In summary, this study highlights the transformative potential of LED technology in optimizing the growth and ornamental quality of foliage plants like Coleus, setting a benchmark for light quality conditions. By leveraging LED technology, producers and nursery growers access enhanced energy efficiency and unparalleled versatility, paving the way for significant advancements in plant growth, color intensity, and two-tone variations. This presents a distinct advantage over conventional production methods, offering a more sustainable and economically viable approach for increased plant reproduction and growth development. Likewise, the specific benefits derived from this study provide invaluable insights, enabling growers to strategically develop ornamental varieties that thrive under optimized light conditions and exhibit heightened visual appeal and market desirability.

Background: Salvia miltiorrhiza Bunge, a medicinal plant belonging to the Lamiaceae family, is commonly used as a health-promoting tea in China. This study investigated and analyzed the improvements in S. miltiorrhiza growth, external quality, vegetation indices, and photosynthetic performance through photoperiod control. Methods and Results: The study was conducted with four different photoperiods: 8, 12, 16, and 24 hours of light period (h·d-1). The results showed that the 12 h·d-1 - 16 h·d-1 photoperiods were most effective for promoting shoot growth. This was determined by evaluating plant sizes, shoot biomass; various remote sensing vegetation indices including normalized difference vegetation index, photochemical reflectance index, and modified chlorophyll absorption ratio index; and five chlorophyll fluorescence parameters (Fv/Fm, ΦDo, ABS/RC, DIo/RC, and PIABS). Similarly, the root growth, root biomass, and external quality parameters (CIELAB color space values and visual score) indicated that a 12 h·d-1 - 16 h·d-1 photoperiod was the most effective. Conversely, continuous light conditions for 24 h·d-1 photoperiod significantly decreased most growth parameters and both shoot and root external qualities, suggesting inefficiency in such conditions. Conclusions: Therefore, the study recommends cultivating S. miltiorrhiza under a 12 h·d-1 - 16 h·d-1 range photoperiod to improve the growth, external qualities, and physiological characteristics.

This study investigated the suitable shading levels for Peperomia species and cultivars, a genus within the Piperaceae family known for its ornamental value as an indoor plant. We examined the effects of four different shading levels (45, 60, 75, and 99 %) using polyethylene (PE) shading films on four Peperomia species and cultivars, namely: P. obtusifolia (L.) A.Dietr., P. quadrangularis (J.V.Thomps.) A.Dietr., P. caperata Yunck. ‘Eden Rosso’, and P. caperata ‘Napoli Nights’. After an eight-week cultivation period, we assessed plant sizes, biomass (i.e. fresh and dry weight), leaf color, chlorophyll content (SPAD units), and five chlorophyll fluorescence parameters (Fv/Fm, ΦDo, ABS/RC, DIo/RC, and PIABS) in Peperomia species and cultivars. The results indicated that P. obtusifolia and ‘Eden Rosso’ exhibited the best growth performance within the 45-75 % shading range, whereas P. quadrangularis and ‘Napoli Nights’ showed optimal performance at the 45 and 60 % shading levels, respectively. All species and cultivars demonstrated reduced growth and biomass under the 99 % shading level, hypothesized to be due to restricted CO2 assimilation under low-light conditions. Leaf color, measured by CIE76 color-difference (ΔE* ab) analysis based on the Commission Internationale de l'Eclairage Lab (CIELAB) color space, remained relatively constant across four different shading levels. Analyses of chlorophyll content and chlorophyll fluorescence revealed that high shading levels might deactivate some reaction centers, although the overall photosynthetic efficiency appeared largely unaffected. The performance index (PIABS) suggested that except for P. quadrangularis, which peaked at the 60 % shading level, P. obtusifolia, ‘Eden Rosso’, and ‘Napoli Nights’ generally performed well under the 45- 75 % shading levels. Therefore, Peperomia plants are capable of tolerating broad shading conditions, except for excessively high shading (99 % shading level). These results indicate that providing suitable shading levels is effective in improving the growth and photosynthetic activity of those several Peperomia species and cultivars.

Danshen (Salvia miltiorrhiza) is a medicinal crop belonging to the Lamiaceae family. Widely used in China as an ingredient for health-promoting tea, danshen is also a noteworthy crop in Korea due to the active development of new cultivars. This study investigated the effects of various photoperiods on growth, external quality, and physiological characteristics of danshen. The photoperiods were designed in four stages: 8, 12, 16, and 24 hours per day (h·d-1). The results indicated that the sizes and biomass of shoots of danshen were most effectively increased under the photoperiod range of 12−16 h·d-1. Additionally, external quality evaluation using the CIELAB color space showed that the external quality of the shoot part of danshen was the best under the photoperiod range of 12−16 h·d-1, while the external quality of the root part was the best under a 16 h·d-1 photoperiod. According to the analysis of chlorophyll fluorescence responses and vegetation indices, which are non-destructive testing methods, there were no significant differences within the photoperiod range of 8−16 h·d-1. However, under a 24 h·d-1 photoperiod, relatively lower values were observed. In conclusion, based on these results, it is determined that cultivating danshen under a photoperiod range of 12−16 h·d-1 is the most efficient.

Danshen (Salvia miltiorrhiza) is a medicinal crop belonging to the Lamiaceae family. Widely used in China as an ingredient for health-promoting tea, danshen is also a noteworthy crop in Korea due to the active development of new cultivars. This study investigated the effects of various photoperiods on growth, external quality, and physiological characteristics of danshen. The photoperiods were designed in four stages: 8, 12, 16, and 24 hours per day (h·d-1). The results indicated that the sizes and biomass of shoots of danshen were most effectively increased under the photoperiod range of 12−16 h·d-1. Additionally, external quality evaluation using the CIELAB color space showed that the external quality of the shoot part of danshen was the best under the photoperiod range of 12−16 h·d-1, while the external quality of the root part was the best under a 16 h·d-1 photoperiod. According to the analysis of chlorophyll fluorescence responses and vegetation indices, which are non-destructive testing methods, there were no significant differences within the photoperiod range of 8−16 h·d-1. However, under a 24 h·d-1 photoperiod, relatively lower values were observed. In conclusion, based on these results, it is determined that cultivating danshen under a photoperiod range of 12−16 h·d-1 is the most efficient.

Salvia miltiorrhiza is a medicinal crop belonging to the Lamiaceae family. It is commonly used in China as an ingredient in health-promoting teas that enhance immunity and prevent diseases. Although some Korean local farmers have reported that S. miltiorrhiza grows vigorously in high temperatures and produces roots with a deep red color, there is no clear evidence or literature to confirm this. Therefore, this study investigated the growth and external quality of S. miltiorrhiza in response to different day and night temperature levels. Day and night temperature treatments were designed into four levels: 20/15, 24/19, 28/23, and 32/27°C, respectively. Among the parameters related to plant sizes, the shoot height and number of roots showed the highest values in the 32/27°C treatment, while other parameters, particularly the shoot width and root length exhibited the highest values in the 28/23°C treatment. In contrast, the majority of parameters, including the fresh weight and dry weight, which are indicative of root biomass, were lowest in the 20/15°C treatment, suggesting that S. miltiorrhiza, a species that prefers relatively high temperatures, thrives in warmer conditions. Importantly, the root fresh and dry weights, which are likely to be correlated with the market value of S. miltiorrhiza, showed the same significance levels within the temperature range of 24/19–32/27°C, but not in the relatively low-temperature treatment of 20/15°C. Thus, cultivation of S. miltiorrhiza is deemed feasible within all temperature ranges except for 20/15°C, with optimal conditions falling within the temperature range of 24/19–32/27°C. The CIELAB a* value, associated with red color, was highest in the comprehensive assessment of the 32/27°C treatment. Moreover, in the 32/27°C treatment, the Royal Horticultural Society (RHS) color chart values were found to indicate a deep reddish or brown-red color, with readings of 166B and 174A. Additionally, the root color obtained the highest visual score in the 32/27°C treatment. Based on previous studies, a* is considered to be related to the content and quantities of tanshinones and other hydrophilic phenolic compounds, which are effective components associated with the orange-red color. Therefore, it is recommended to cultivate S. miltiorrhiza at a high temperature of 32/27°C to achieve high growth rates, excellent external quality, and produce superior S. miltiorrhiza plants.