• Journal of Plant Biotechnology
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• v.45 no.2
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• pp.117-124
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• 2018

The imports of Centella asiatica L. Urban are increasing year-by-year due to the fact that its extract is a raw material used for skin wounds and in cosmetics. However, studies on the cultivation and identification of native C. asiatica species in Korea have been extremely rare. Therefore, this study was conducted in order to investigate the physiological and functional activity of Korean native C. asiatica plant cultivated in Hapcheon, Gyeongsangnam-do, Korea. As a result, the highest antibacterial and anti-inflammatory activities were examined with methanol extract while skin-whitening and wrinkle improvement were examined with water extract. Seven bacterium and one fungus were treated with 50% methanol extracts of C. asiatica and most of the bacterium showed similar or low levels of antibacterial activity compared to the control group of Omiza (Schisandra chinensis) extract, except for Streptococcus pyogenes, which showed higher antimicrobial activity than that of Omiza extract. However, neither C. asiatica and Omiza extracts showed antimicrobial activity against the fungus, C. albicans. The results of anti-inflammatory effect analyses with Raw 264.7 cells confirmed that the treatment of methanol extract reduced the level of NO by 50% or more compared to the control group. In addition, the water extract showed the highest reduction of melanin content of up to 20% more than the control group when examined with B16F10 cell line, indicating a significant skin-whitening effect. Furthermore, we were able to show the significant skin wrinkle improvement caused by C. asiatica extract with NHDF cell as an indicator, but strong cytotoxicity was also observed, suggesting that further studies are necessary.

• Korean Journal of Ecology and Environment
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• v.46 no.4
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• pp.588-595
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• 2013

This study investigated the influence of temperature and $CO_2$ increase on phytoplankton growth and community structure during cold water season (spring) in Lake Paldang, Korea. Four experimental treatments of temperature and $CO_2$ manipulation were prepared in the laboratory batch culture: (1) Control; ambient low temperature ($6{\pm}2^{\circ}C$) and low $CO_2$ (air level, $400mgL^{-1}$), (2) T1; low temperature and high $CO_2$ ($800mgL^{-1}$), (3) T2; high temperature ($20{\pm}2^{\circ}C$) and low $CO_2$, (4) T3; high temperature and high $CO_2$. Algal growth experiment was carried out for 10 days under the light intensity of $70{\mu}mol\;m^{-2}s^{-1}$ (L :D=24 : 0). The level of pH decreased in both T1 and T3, due to dissolution of added $CO_2$. The dominant phytoplankton species of ambient water, Cyclotella meneghiniana succeeded to Fragilaria capucina var. gracilis in high-temperature treatment groups (T2 and T3). Cyanobacteria were very rare at the beginning of the experiment, while Oscillatoria limnetica appeared in only high-temperature groups (T2 and T3) at $6{\sim}7^{th}$ day. $CO_2$ addition in ambient temperature (T1) induced the highest phytoplankton growth, and thereby producing the highest average cell density of $3.27{\pm}0.33\;10^4\;cells\;mL^{-1}$, followed by T2 ($2.65{\pm}0.26\;10^4\;cells\;mL^{-1}$), T3 ($2.09{\pm}0.16\;10^4\;cells\;mL^{-1}$), and Control ($1.86{\pm}0.13\;10^4\;cells\;mL^{-1}$) (F=7.167, p=0.000). In summary, temperature increase changed the phytoplankton community structure and $CO_2$ increase promoted the phytoplankton growth during the cold spring season in Lake Paldang, suggesting a potential effect of climate change on freshwater phytoplankton.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.35 no.2
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• pp.77-86
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• 2017

A study on the population ecology of gregarious Wisteria habitat was conducted in Beomeosa temple, Busan. The area has been protected since it was designated as No. 176 natural monument in 1966. Such a large habitat of native wisteria (Wisteria floribunda DC.) in Korea is very rare so that it has a very high academic value. However, there are no high-resolution researches on the distribution and ecology of wisteria in the Gregarious Wisteria Habitat of Beomeosa Temple. The study aimed to identify the distribution and characteristics of wisteria populations in the Wisteria habitat. The study identified the distribution of Wisteria, RCC, the climbing direction, the plant and flora in the research area in the Gregarious Wisteria Habitat of Beomeosa Temple in Busan and the surrounding areas based on an on-site research. As a result, the total number of the wisteria populations in the research area was confirmed to be 1,158 and the RCC of wisteria was on average 69.0 mm (${\pm}45.5$) and in maximum 365 mm. In terms of the climbing direction, the number of wisteria that climbs clockwise or counterclockwise was determined to be 40. It was identified that there are 28 taxa of the climbing plant species and the wisteria of the same kind was the most favorable. The populations were found to be dispersed adjacent to the valleys, and were found to be maintained by constant disturbance. 76.6 % of the population was found to be distributed in the valley forest, and the Carpinus tschonoskii-Pseudosasa japonica forest, Pueraria lobata community and Pinus densiflora forest were found to be relatively dispersed. The study proposed to conduct the follow-up researches to preserve the wisteria that is spreading in this research area, the wisteria with the highest RCC and regional habitat through continuous monitoring; and maintain the protection area of No. 176 natural monument; and discussed the management measures and approaches that reflect the habitat.

• Korean Journal of Environment and Ecology
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• v.36 no.2
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• pp.177-201
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• 2022

Following the adoption of the global plant conservation strategies at the Conference of the Parties for Biodiversity Conservation, diligent actions to achieve each targets are actively carried out. In particular, the need for ecological conservation research to achieve targets 2 and 7 of GSPC-2020 has increased. The priority taxa to accomplish the objectives of GSPC-2020 are rare and endemic plants. In particular, endemic plants with limited distribution in specific regions are evaluated to face a high risk of extinction. To address the necessity to preserve endemic plants, we investigated the distribution of Prunus choreiana H. T. Im, a Korean endemic plant. After that, we examined the vegetational environment of the habitat of P. choreiana and evaluated its population structure. The productivity of its fruits and the effects of pollinators on fruit production were evaluated as well. The fruiting ratio was calculated based on the number of flowers produced. Lastly, we observed the annual growth characteristics of P. choreiana. The habitats of P. choreiana did not show a specific type of vegetation. All of them were located in a limestone area of Gangwon-do in the central Korean Peninsula and occupied a site where the coverage of the tree layer and the sub-tree layer was not high or did not exist. The population structure of P. choreiana contained a high proportion of mature plants capable of producing fruits and a low proportion of seedlings and Juvenile plants. We found that the production of fruits required pollinators and was affected by the performance of each plant. Although P. choreiana produces many flowers, only a maximum of 20% and only 2-6% on average bear fruits. These flowering characteristics may be due to pollinators' low abundance and activity during the flowering season (between mid-March and early April), suggesting that many flowers are needed to attract more pollinators. We rarely observed the re-establishment of seedlings in the population of P. choreiana. Despite that, we predict the population to persist owing to its long lifespan and periodic production of numerous fruits. However, if the tree layer and sub-tree layer in competing status with P. choreiana increase their crown density, they are expected to inhibit the growth of P. choreiana and affect the risk of its extinction. Therefore, the current changes in the vegetational environment of the habitats are expected to decrease the number and extent of P. choreiana in the long term. The results of this study may serve as primary and important data necessary for the achievement of GSPC-2020 objectives.

• Korean Journal of Environment and Ecology
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• v.36 no.6
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• pp.639-650
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• 2022

Abeliophyllum distichum Nakai, a rare plant with distylous characteristics, is native to certain parts of the Korean Peninsula. It is registered on the IUCN Red List of Threatened Species as a globally endangered plant. This study was conducted to establish an appropriate local conservation management plan suitable for future A. distichum populations by comparing and analyzing the flowering characteristics and population size according to distyly based on the results of quantitative surveys in 14 regions, including 8 areas with native populations of A. distichum and 6 natural monument populations. The number of individuals appearing in each population group was surveyed, and the flowering individuals were identified by style as being either pin or thrum flower types as they were being examined and recorded on the site. In total, 13,130 individuals of A. distichum (7,003 flowering and 6,127 non-flowering individuals) were recorded, but the balance of the number of pin- and thrum-flowered individuals in each population was not significant (p<0.05), indicating an imbalanced state. In particular, the Yeongdong (YD) population was very disproportionate compared to other populations, suggesting that its genetic diversity was low and the possibility of inbreeding was high. The average flowering and fruiting rates by management unit were much higher in the natural monument populations (89.2% and 55.3%, respectively) than in the natural habitat populations (39.0% and 8.5%, respectively). It may be due to a difference in reproductive growth resulting from light inflow into the forest caused by the upper crown closure. The area of occupation (AOO) of A. distichum on the Korean Peninsula covered an area of 23,224.5 m². Although the natural monument population was smaller than the natural habitat population, its density was higher, likely as a result of the periodic management of natural monument populations, where the installation of protective facilities in certain areas restricts population spread. Conservation of A. distichum populations requires removing the natural monument populations suspected of anthropogenic and genetic disturbances and expanding the conservation priority population by designating new protected areas. Although the habitats of natural monument populations are managed by the Cultural Heritage Administration and local governments, there are no agencies that are responsible for managing natural habitat populations. Therefore, institutional improvement in the overall management of A. distichum should be prioritized.

• Korean journal of applied entomology
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• v.13 no.4 s.21
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• pp.181-204
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• 1974

The study has been carried out to investigate the occurrence, damage, host range, transmission and control of rice stripe virus in Korea since 1965. 1 Disease occur「once and damage : The virus infection during the seedling stage ranged from 1.3 to $8\%$. More symptom expression was found in regrowth of clipped rice than infected intact plants, and the greater infection took place in early seasonal culture than in ordinary seasonal culture. A higher incidence of the disease was found on the rows close to the bank, and gradually decreased toward the centre of the rice paddy. Disease occurrence and plant maturity was highly correlated in that the most japonica rice types were diseased when they were inoculated within 3 to 7 leaf stage, and$50\%$, $20\%$ and no diseaseb were found if they were inoculated at 9, 11 and 13 leaf stages, respectively. Symptom expression required 7-15 days when the plants were inoculated during 3-7 leaf stages, while it was 15-30days in the plants inoculated during 9-15 leaf stages. On Tongil variety the per cent disease was relatively higher when the plants were infected within 1.5-5 leaf stages than those at 9 leaf stage, and no disease was found on the plants infected after 15 leaf stage. The disease resulted in lowered growth rates, maturity and sterility of Tongil variety although the variety is known as tolerant to the virus. 2. Host range: Thirty five species of crops, pasture grasses and weeds were tested for their susceptibility to the virus. Twenty one out of 35 species tested were found to be susceptible. and 3 of them, Cyperus amuricus Maximowics var. laxus, Purcereus sanguinolentus Nees and Eriocaulon robustius Makino, were found as new hosts of the virus. 3. Transmission: The vector of the virus, Laodelphax striatellus, produces 5 generations a year. The peak of second generation adults occurred at June 20th and those of third was at about July 30th in Suweon area. In Jinju area the peak of second generation adult proceeded the peak at Suweon by 5-7 days. The peaak of third generation adult was higher than the second at Jinju, but at Suweon the reverse was true. The occurrence of viruliferous Laodelphax striatellus was 10-15, 9, 17, 8 and about $10\%$ from overwintered nymph, 1st generation nymph, 2nd generation adult, End generation nymph and the remaining generations, respectively. More viruliferous L. striatellus were found in the southern area than in the central area of Korea. The occurrence of viruliferous L. striatellus depended on the circumstances of the year. The per cent viruliferous vectors gin 2nd and 3rd generation adult, however, was consistantly higher than that of other generations. Matings of viruliferous L. striatellus resulted in $90\%$ viruliferous progenies, and the 3rd, 4th and 5th instars of the vector had higher infectiviey than the rest of the vector stages. The virus acquisition rate of non-viruliferous L. striatellus was $7-9\%$, These viruliferous L. striatellus, however, could not transmit the virus for more than 3 serial times. The optimum temperature for the transmission of the viru3 was $25-30^{\circ}C$, while rare transmission occurred when the temperature was below $15^{\circ}C$. The per cent of L. striatellus parasitization by Haplogonatopus atratus were $5-48\%$ during the period from June to the end of August, and the maximum parasitization was $32-48\%$ at around July 10. 4. Control: 1) Cultural practices; The deeper the depth of transplanting more the disease occurrence was found. The higher infection rate, $1.5-3.5\%$, was observed during the late stages of seedling beds, and the rate became lower, $1.0-2.0\%$, in the early period of paddy field in southern area. Early transplanting resulted in more infection than early seasonal culture, and the ordinary seasonal culture showed the lowest infection. The disease also was favored by earlier transplanting even under tile ordinary seasonal culture. The higher the nitrogen fertilizer level the more the disease occurrence was found in the paddy field. 2) Resistant varieties; Tongil varieties shelved the resistant reaction to the virus in greenhouse tests. In the tests for resistance on 955 varieties most japonica types shelved susceptible reactions, while the resistant varieties were found mostly from introduced varietal groups. 3) Chemical control; Earlier applications of chemicals, Disyston and Diazinon, showed better results when the test was made 4 days after inoculation in the greenhouse even though none of the insecticides shelved the complete control of the disease. Three serial applications of chemicals on June 14, June 20 and June 28 showed bettor results than one or two applications at any other dates under field conditions.