• Journal of Aquaculture
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• v.19 no.3
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• pp.216-221
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• 2006

The Effect of different temperatures and photon irradiance on the growth of crust and the regeneration of tissue fragments of the commercially important red alga Grateloupia acuminat Okamura were examined in laboratory cultures. The tetraspore developed into basal crusts and produced upright thalli. Crust grew very fast at $25^{\circ}C$ and $80{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ after one week in indoor culture. However, they stopped growing after three weeks. Maximum growth was $275{\mu}m$ in diameter. They required four weeks to get upright thalli at $5^{\circ}C$, while only three weeks were required at $10^{\circ}C$. When different light intensities were compared at $15^{\circ}C$, cells of the crusts were well differentiated $80{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ and consistently divided so that upright thalli were produced. In aeration culture, the upright thalli grew up to 6.5 cm in length within 4 months. Thus, it is possible to produce mass cultures of Grateloupia in the field. In addition, female and male gametophytes developed from the tetraspores and they were fertilized to produce tetrasporohyte thalli. By this procedure, the normal life cycle of the red alga G. acuminata was completed.

• Journal of Conservation Science
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• v.37 no.2
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• pp.90-100
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• 2021

Outdoor cultural buildings and their accessories receive different amounts of solar radiation depending on their location's latitude, azimuth, and tilt. Shading is also affected by the surrounding terrain and objects, necessitating individual and quantitative shading analysis. In July 2019, this study conducted a shading analysis on the tops, midpoints, and bottoms of wooden pillars in the azimuth of Cheongpunggak, a traditional building in South Korea's National Research Institute of Cultural Heritage. The shading analysis found that the solar access/shade predicted by the solar trajectory meter was 30 minutes slower than measured in the field. The highest solar access and solar radiation levels came from the south, followed by the west, east, and north. The pillars' bases received the highest solar access and solar radiation, followed by their midpoints and tops. Solar access was high at tilt 90°, but solar radiation was high at tilt 0°, due to the light-collection efficiency and the irradiance. Shading on the pillars' tops was caused by the roof eaves, while shading on the midpoints and bases were affected by the surrounding pillars, topography, and other objects. Simultaneous solar access at the tops, midpoints, and bottoms was possible for 365 days for the northwest, west, and southwest pillars but only from October to March for the south and southeast pillars.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.25 no.4
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• pp.117-131
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• 2020

Although most species in genus Zostera inhabit shallow coastal areas and bays with weak wave energy, the Asian eelgrass, Zostera asiatica is distributed in deep water depth (8-15 m) unlike other seagrasses on the eastern coast of Korea. To examine factors limiting distribution Z. asiatica in relatively deep coastal areas, a transplantation experiment was conducted on October 2011, in which Z. asiatica shoots were transplanted from the reference site (donor meadow, ~9 m) to the shallow transplant site (~3 m). We compared shoot density, morphology, and productivity of Z. asiatica as well as environmental factors (underwater irradiance, water temperature, and nutrients) between the reference and transplant sites from October 2011 to September 2012. Shoot density and shoot height of transplants dramatically decreased within a few months after transplantation, but were similar with Z. asiatica in the reference site during spring. Shoot productivity were significantly higher in the transplant site than in reference site because of high light availability and nutrient concentrations. Transplants showed photoacclimatory responses such as higher rETR_max and E_k and lower photosynthetic efficiency in the transplant site than those in the reference site. Most of Z. asiatica transplant in the shallow transplant site disappeared in summer, which may be due to the high wave energy and physical damages induced by typhoons (TEMBIN and SANBA) in August and September 2012. According to the results of this study, Z. asiatica could not survive in shallow areas despite of more favorable light and nutrient conditions. Thus, Z. asiatica may restrictively occur in deep areas to avoid the intense physical stresses in the shallow area on the east coast of Korea.

• Korean Journal of Ecology and Environment
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• v.40 no.1
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• pp.61-71
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• 2007

The photosynthetic characteristics and primary production by phytoplankton in open waters of two wetlands (the Banwol and the Donghwa wetland) of Sihwa Constructed Wetland with different water chemistry were investigated to provide the information for the wetland management considering the water treatment efficiency. During the study period (from March to October, 2005) the primary productivity in open waters ranged from 481 to 11,275 mgC $m^{-2}$ $day^{-1}$, which is very high compared with the eutrophic level of 600mgC $m^{-2}$ $day^{-1}$. From the analysis of the photosynthesis-irradiance (P-I) model parameters, the photosynthetic characteristics may be affected by different concentration and ratio of nutrient (N and P) between two wetlands. Assimilation number (AN) was higher in the Donghwa wetland (average AN: 8.5gC $gChl^{-1}$ $hr^{-1}$) with high P and low N/P ratio than the Banwol wetland (average AN: 5.8gC $gChl^{-1}$ $hr^{-1}$) with high N and high N/P ratio. This result indicates that AN may be concerned with phosphorus than nitrogen and low NIP ratio. Positive correlation (R=0.81) was observed between the initial slope and AN, implying that AN was high in case of phytoplankton having more active photosynthesis ability under low light. On the other hand, maximum photosynthesis (Pmax) was related positively with chlorophyll a concentration showing correlation coefficient of 0.47. In this study, considering the high primary production through phytoplankton photosynthesis in open waters of Sihwa Constructed Wetland, the produced organic matter by phytoplankton may affect the water quality within wetland and its efficiency of water treatment. Also, the photosynthetic characteristics may be affected by different nutrient enrichment (especially phosphorus) of wetlands. This study suggests that the production by phytoplankton and its characteristics in open water of constructed wetland for water treatment should be considered to improve the removal efficiency of organic matter.

• Journal of Bio-Environment Control
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• v.32 no.2
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• pp.157-164
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• 2023

Codonopsis lanceolata (S. et Z.) Trautv. is mainly cultivated in Korea and China as a medicinal crop. C. lanceolata is difficult to produce plug seedlings in the summer, because C. lanceolata has a low germination rate and is vulnerable to high temperatures. Cold treatment is effective in breaking dormancy of seeds and increasing the germination rate. Shading cultivation can control the solar irradiance received by plants and reduce the damage by high temperatures and strong light. This study was conducted to examine the appropriate cold treatment period for the improving germination of C. lanceolata, and shading level during the summer seedling period. Cold treatment experiments were conducted for 0 (control), 1, 2, 3, and 4 weeks at 4℃ before sowing. In the shading experiment, C. lanceolata was grown for 45 days with 0 (non-treatment), 45, 75% shading levels. Cold treatment for one week significantly improved the germination energy. The plant height, leaf area, and fresh and dry weights of C. lanceolata seedlings were significantly increased under the 45% shading level. Total root length, root surface area, and the number of root tips were significantly higher in shading treatment (45 and 75%) than in non-treatment. The C. lanceolata seedling's compactness and Dickson's quality index were the highest at 45% shading level. Therefore, these results recommended sowing C. lanceolata after cold treatment for one week at 4℃, and 45% shading level could stably culture C. lanceolata plug seedlings during the high temperature period.