Yeong Sunwoo’s scientific contributions

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.

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.

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.