• Korean Journal of Plant Resources
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• v.37 no.2
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• pp.110-119
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• 2024

This study was conducted to provide information on the possibility of using Rhododendron micranthum as resource plant. Through polyphenol profiling of R. micranthum shoot extract, useful components were selected and the content of useful components and antioxidant activity by extraction solvent were compared. As a result, 37 polyphenol compounds were identified in R. micranthum shoot extract through LC-ESI-MS analysis. Contents by extraction solvent were compared of chlorogenic acid, astragalin, myricetin, and afzelin. Chlorogenic acid was highest at 6.57±0.12 mg/g in the ethanol extract, astragalin was 2.29±0.02 mg/g in the ethanol extract, myricetin was 4.77±0.06 and 4.52±0.27 mg/g in the methanol, ethanol extracts, and afzelin was highest at 0.10±0.01 mg/g in the methanol extract. Total polyphenol content of the R. micranthum shoot extract according to the extraction solvent was highest in the ethanol extract at 80.01±2.36 mg/g, and total flavonoid content was also highest in the ethanol extract at 78.08±3.44 mg/g. The IC₅₀ value of DPPH radical scavenging activity according to the extraction solvent of R. micranthum shoot was lowest in methanol extract at 943.57±10.68 mg/L, and the IC₅₀ value of ABTS radical scavenging activity was also lowest in methanol extract at 641.60±7.58 mg/L.

• Korean Journal of Plant Resources
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• v.23 no.4
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• pp.374-378
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• 2010

Determining plant moisture characteristics is an essential study not only for cultivation, but also for ex-situ conservation. In this study, employing pressure-volume curve we examined moisture characteristics of Rhododendron micranthum, known as rare plant, with the aim of its ex-situ conservation. Several individuals growing in Mt. Worak, Youngwol-gun Yeonha-ri and Bongwa-gun Seokpo-ri were selected for this study, from which we collected leaves. The original bulk osmotic pressure at maximum turgor(${{\Psi}_o}^{sat}$)was -1.5 MPa in those of Mt. Worak and Seokpo-ri, which is somewhat lower than that of Yeonha-ri(-1.2 MPa). It appeared that the osmotic pressure at incipient plasmolysis(${{\Psi}_o}^{tlp}$) of leaves collected in both Mt. Worak and Seokpo-ri were -1.29 MPa, and -1.26 MPa, respectively, which are lower than that of Yeonha-ri(-1.02MPa). Maximum bulk modulus of elasticity($E_{max}$) was 14.0 MPa, 8.67 MPa in leaves collected from both Seokpo-ri and Mt. Worak, respectively, those value of which were approximately 3 times higher than that of Yeonha-ri(4.00 MPa). The values of $RWC_{tlp}$(Relative water content at incipient plasmolysis) of leaves collected in three areas, were roughly 83%, suggesting that Rhododendron micranthum has relatively high capability of containing water. Our finding on moisture characteristics of Rhododendron micranthum is similar to those of other Rhododendron spp. We suggest that individuals growing in both Worak and Seokpo-ri, are preferable to those in Yeonha-ri for ex-situ transplantation since those individuals are found to have better drought resistance.

• Journal of the Korean Institute of Landscape Architecture
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• v.17 no.2
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• pp.41-46
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• 1989

Rhododendron micranthum grown over the area of Kyoung Puck, Kang Weon Province is showy and very attractive evergreen broad-leaned shrub of shade resistance. This shrub is considered very useful for exploiting as a garden plant. Environments, growth characteristics and vegetation association in the wild habitat and in the garden planted with this shrub, were investigated to find out some appropriate means of propagation and cultivation of this shrub. The results thus obtained were stated as follows ; 1. Light intensity for the native habitat ranged in the proximity of 9%. The most abundant stand of this shrub occurred in the northen side of mountains, while still some plants were found in the eastern sides also. 2. Soil of the native habitat was acidic (pH 4.4) and infertility. 3. Average elevation of the native habitat was shown to be 230m above the sea level. 4. The plant of the native habitat showed an average of 3.9 new shoots per branch, whereas that of the garden planted (light intensity 100%) showed 1.2, 5% of an average was for sun-burn leaves were noted, while garden Plants(light intensity 100%) showed 90% of them. 5. Other tree species associated with Rhododendron micrathum in the native habitat were primarily Pinus densiflora and secondarily Sorbus alnifolia, hemerocallis aurautiaca, Rubus crataegifolius, and Salix hulteni. 6. Vegetation rate of plant habitats in the Rhododendron growing area was observed to be 0 to 80% involving 27 to 50 species of associated trees in the vegetation for the 10${\times}$10m quadrat area.

• Journal of Korean Society of Forest Science
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• v.95 no.1
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• pp.55-59
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• 2006

The objectives of this study, an analysis of the morphological characteristics among six provenances of a rare Rhododendron micranthum could be used for the conservation of gene resources and could provide information on superior trees selection. The following results were obtained. Approximately Mt.worak region showed larger values at petal character. On the other hand, Bonghwa region showed smaller values at petal character. Yeonha-ri region showed larger values at leaf character. On the other hand, Bonghwa region showed smaller values at leaf character. The results of principal component analysis (PCA) for morphological characteristics showed that the first for principal components(PC's) explained 41.6% of the total variation. From th third PC explained 81.5% of the total variation. The first PC was correlated with those characteristics that were mainly related to the Petal length (PL), Leaf length (LL) width (LW), Stigma length (SL). The second PC was correlated with the Petiole length (PTW), Anther length (AL). The third PC was correlated with the Flower pedicel length (FPL), Filament length (FL). Therefore, these characteristics was important to analysis of the variation for morphological characteristics among provenances of Rhododendron micranthum. Cluster analysis using single linkage method based on morphological characteristics showed that six provenances of Rhododendron micranthum could be clustered into three groups. Group I is Jicdong-ri, Group II is Mt.worak and Yeonha-ri, and Group III is Taeback, Bonghwa, and Samcheok. These results corresponded well with that of principal component analysis.

• Landscaping Tree
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• s.127
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• pp.26-27
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• 2012

• Journal of Bio-Environment Control
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• v.21 no.2
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• pp.147-152
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• 2012

This study was conducted to investigate the photosynthetic R. micranthum by natural habitats. In the results, natural habitats didn't affect values of light saturated point, light compensation point and photosynthetic capacity of R. micranthum. We investigated light response curve and chlorophyll content at each habitat. Light compensation points were 11.8 ${\mu}mol\;m^{-2}\;s^{-1}$, 11.5 ${\mu}mol\;m^{-2}\;s^{-1}$ and 10.4 ${\mu}mol\;m^{-2}\;s^{-1}$ in Seokpo-ri, Yeonha-ri, and Mt. Worak. Light saturation points showed that R. micranthum is shade tolerant specie which has the light saturation point approximately 500~600 ${\mu}mol\;m^{-2}\;s^{-1}$. Photosynthetic rates of R. micranthum leaves were 5.5 ${\mu}mol\;m^{-2}\;s^{-1}$, 5.4 ${\mu}mol\;m^{-2}\;s^{-1}$ and 5.6 ${\mu}mol\;m^{-2}\;s^{-1}$ in Seokpo-ri, Yeonha-ri and Mt. Worak. On the other hand, since between $20^{\circ}C$ and $30^{\circ}C$, it appeared that the values of net photosynthetic rates of R. micranthum leaves in all sites were high. Especially, the rates were highest at $25^{\circ}C$. Because of low stomatal transpiration rate in saturation radiance, the moisture utilization efficiency in Yeonha-ri was lower than other habitats. Rates of chlorophyll a, chlorophyll b, and total chlorophyll content in Mt. Worak were no significant difference. Therefore R. micranthum has characteristic of shade tolerant species. The moderate temperature for R. micranthum is between $20^{\circ}C$ and $30^{\circ}C$.

• Journal of Life Science
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• v.28 no.8
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• pp.938-944
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• 2018

This study evaluated tyrosinase, elastase inhibitory, and antioxidant activities of fermented Rhododendron micranthum Turcz. extract using a lactic acid bacterium, Lactobacillus rhamnosus. The optimum conditions for fermentation of R. micranthum Turcz. extract were $37^{\circ}C$ and 3% R. micranthum Turcz. extract for 3 days based on the bacterial cell number, total phenolic compounds, DPPH radical scavenging activity, and tyrosinase and elastase inhibitory activity. After culture for 3 days using 3% R. micranthum Turcz. extract, the cell mass of L. rhamnosus reached $5.7{\times}10^9CFU/ml$. The results indicated that R. micranthum Turcz. extract can be used for industrial lactic acid bacteria culture. After fermentation under optimum conditions, the total content of phenolic compounds of the fermented R. micranthum Turcz. extract was 157 GAE mg/ml, and the $IC_{50s}$ of DPPH radical scavenging activity, ABTS radical scavenging activity, and tyrosinase and elastase inhibitory effects were 78.8, 79.8, 329.1, and $449.5{\mu}g/ml$, respectively. The fermented R. micranthum Turcz. extract exhibited 1.2-, 1.3-, 1.5-, 2.4-, and 5.6-fold higher total content of phenolic compounds, DPPH radical scavenging activity, ABTS radical scavenging activity, and tyrosinase and elastase inhibitory effects than the nonfermented R. micranthum Turcz. extract. These results indicated that fermented R. micranthum Turcz. extract using L. rhamnosus can be used for developing new natural functional ingredients for the health food or cosmetic industry.

• Korean Journal of Plant Resources
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• v.17 no.3
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• pp.227-238
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• 2004

Rhododendron micranthum is an endangered species in Korea. In order to develop the strategy of gene diversity conservation, estimation of the amount of genetic diversity, the genetic variation and relationship in the native populations of Rh. micranthum was performed on the basis of AFLP and RAPD analysis. Analysis of 56 accessions derived from 6 populations of Rh. micranthum with four AFLP primer combinations and ten RAPD primers detected a total of 33 polymorphic AFLP fragments and 15 polymorphic RAPD fragments, respectively. By UPGMA cluster analysis with molecular markers, the 56 accessions were grouped into three major clusters at 73.3% genetic similarity; group I consists of most accessions of populations I, II, IV, V and Ⅵ, group II consists of 7 accessions of population III, and group III consists of only two accessions of population IV. The geographic locations of the most accessions derived from six populations were not related to their position in the UPGMA cluster analysis, except for several accessions of populations III and IV. The genetic similarity of among six populations measured by AFLP and RAPD markers ranged from 0.66 to 0.99. Among them, population Ⅵ showed the highest GS with means of 0.87, while population I showed the lowest GS with means of 0.78. This result will be useful for designing the strategy of conservation in the native populations of Rh. micranthum.

• Korean Journal of Environment and Ecology
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• v.24 no.5
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• pp.582-590
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• 2010

Baekdudaegan field survey has been proposed and presented as a various plan such as field survey analysis, management and restoration plan, etc. Whereas, the concerns of the Jeongmaek has increased continuously, nevertheless there is no research of present condition for Jeongmaek. This paper is to contribute to suggest for management and restoration as a basic study of vegetation structure in Yongso valley. We set up 30 plots($100m^2$) to verify the vegetation structure. As a result of classification analysis used by DCA, the type of 5 communities i.e. Pinus densiflora community, Betula schmidtii community, Populus maximowiczii community, Quercus mongolica community, Q. variabilis community were the most representative of Yongso valley vegetation communities. P. densiflora community was mainly distributed in the ridge of mountain, ridge of steep slope and stony area. In that reason, they avoid to compete with B. schmidtii community and Q. spp. community. In addition, the appearance of Rhododendron micranthum was mainly characteristics in the P. densiflora community. Species diversity indices(H') of groups were ranged from 0.7914~0.9942, the tree ages were 30~115 years. According to these results, the forests of Yongso valley not only form muti-layer vegetation structures but also have a great ecological value for protection and preservation.

• Korean Journal of Environmental Biology
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• v.24 no.4
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• pp.359-367
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• 2006

The vascular plants of this site were identified as 641 taxa through field investigation; 101 families, 340 genera, 547 species, 80 varieties, 12 forms, 1 subspecies and 1 hybrid. Based on the Rare plants of the Forest Service and Korea Forest Research Institute, 9 taxa were listed except implanted species; Loranthus tanakae, Aristolochia manshuriensis, Aristolochia contorta, Viola albida, Cypripedium macranthum, Schpolia japonioa, Acanthopanax chiisanensis, Rhododendron micranthum. Based on the Korean endemic plants, 18 taxa were listed; Salix purpurea var, japonica, Asarum sieboldii var. mandshuricum for. misnadrum, Persicaria lapathifolia for. alba, Pseudostellaria sylvatica, Aconitum pseudolaeve var. erectum, Corydalis maculata, Corydazis albipetala, Corydalis grandicazyx, Cardamine amaraeiormis, Chrysosplenium barbatum, Filipendula glaberrima, Lespedeza x tomentella, Acanthopanax chiisanensis, Melampyrum setaceum var. nakaianum, Weigela subsessilis, Adenophora triphylla var. hirsute, Cirsium setidens, Saussurea pseudogracilis. Specific plant species by floral region were total 81 taxa (12.6%); Prunus yedoensis in class V, 13 taxa (Thuja orientalis, Cimicifuga heracleiiolia, Sedum middendorffianutn, Rhododendron micranthum, etc.) in class IV, 17 taxa (Equisetum palustre, Aceriphyllum rossii, Angelica gigas, Cirsium setidens, etc.) in class III, 15 taxa (Heloniopsis orientalis, Lychnis cognata, Saxifraga oblongifolia, Viola orientalis, etc.) in class II, 35 taxa (Hosta capitata, Cimicifuga simplex, Chrysosplenium flagelliferum, Campanula punctata, etc.) in class I. So, the naturalized plants were listed 53 taxa and the naturalization index was 8.2%, urbanization index was 20.7%.