• The Korean Journal of Ecology
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• v.11 no.4
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• pp.201-212
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• 1988

Ansan city in the coastal area of the mid-western Korea is known as a newly industrialized city(73.44$Km^2$, 127, 000 persons), with the increase rate of 27.8% in population and mean density of 1, 732 persons/$Km^2$. According to the census of the city(1986), it consists of cultivated field(36.8%), forest(34.2%), industrial area(7.4%), residential area(4.1%) and others(12.5%). The forest vegetation in the city is composed of four associations and two subassociations as follows; Pinus rigida, Pinus densiflora-Rhododendron mucronulatum, Quercus mongolica-Rhododendron mucronulatum and Robinia pseudo-acacia asociation, and Quercus mongolica-Corylus sieboldiana var. mandshurica and Robinia pseudoacacia-Alnus hirsuta subassociation. Various environmental conditions have been changed with the progress of urbanization of the city, since 1977. For example, a heat island phenomenon, which is the air temperature of 2 or 3$^{\circ}C$ higher in the central area than that of the boundary area, and floral changes caused by air pollutants such as decreasing bryophyte species along increasing SO$_2$ concentration.

• Proceedings of the PSK Conference
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• 2000.10a
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• pp.220.1-220.1
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• 2000

• Horticultural Science & Technology
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• v.16 no.1
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• pp.33-36
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• 1998

This study was carried out to examine the effects of cutting dates and rooting promoters on rooting of the Rhododendron mucronulatum Turcz. The rooting percentage in greenwood cutting was high in June and decreased after July 3, when reproductive growth began. The best rooting percentage(92.5%) occurred when cutting was completed on June 12. There was no difference in rooting potentials between the greenwood straight cutting and the greenwood heel cutting. Cuttings of R. mucronulatum for. albiflora showed high rooting percentage(85%) similar to the cuttings of R. mucronulatum. Dipping cuttings in NAA $2,000mg{\cdot}L^{-1}$ solution for 15 sec increased the rooting percentage up to 97.5%, and also promoted root growth.

• Journal of the Korean Wood Science and Technology
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• v.48 no.2
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• pp.166-180
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• 2020

Rhododendron schlippenbachii have been used as a medicine because of their various biological activities. In this study, R. schlippenbachii ethanol extract was evaluated for the treatment of vitiligo. The R. schlippenbachii ethanol extract did not show any cell cytotoxicity. The effect on mushroom tyrosinase and cellular tyrosinase activities were further assessed. In addition, the determination of melanin content in melanocytes was measured using both the B16 melanoma cells and C57BL/6J Ler-vit/vit mice. Finally, the existence of quercetin in R. schlippenbachii was confirmed by qualitative analysis using HPLC. The results clearly demonstrated the R. schlippenbachii extract enhanced melanogenesis and also increased tyrosinase activity in cultured melanoma cells and C57BL/6J Ler-vit/vit mice. In addition, treatment with R. schlippenbachii extract led to a higher content of melanin and eumelanin in C57BL/6J Ler-vit/vit mice hair than in control (untreated) mice, which demonstrated the therapeutic effect of hair-graying associated with vitiligo. Finally, we confirmed a notable increase in melanocytes in the skin of C57BL/6J Ler-vit/vit mice treated with R. schlippenbachii extract compared with the control. Extracts of R. schlippenbachii was shown to be potent tyrosinase and melanin synthesis activator in B16 melanoma cells. The R. schlippenbachii extract have significantly higher melanin content than the untreated control in C57BL/6J Ler-vit/vit mice hair. The results suggest that R. schlippenbachii extract might be considered as an alternative treatment for improvement of vitiligo.

• The Korean Journal of Ecology
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• v.22 no.6
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• pp.325-335
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• 1999

Empetrum nigrum dominant community or Rhododendron mucronulatum and R. yedoense var. poukhanense dominant shrub community are developing above l,500m on Mt. Halla in Cheju Island, Korea. These communities were formed as a result of the forest of Abies koreana regression by grazing or erosion over a long period of time. This study was conducted using the phytosociological method and it clarified the floristic composition of the community in Cheju Island by comparing with a similar community in Japan. Also this study interpreted the development data of these communities and considered community succession. As a result of our interpretation, shrub community of Cheju Island is recognized as two associations, Festuco obinae-Empetretum nigrum ass. nov and Rhododendretum mucronulatum ass. nov. Each association of Cheju Island is composed of endemic species of Cheju Island. related to the Korean peninsula and to Japan. The two associations are divided into 8 sub-units but each community development has been created with longtime grazing and prescribed fire. Maybe the location stability by stoppage of interference and grazing will process community transition Quickly. Comparing the shrub communities of Cheju Island with Maianthemo-Rhododendretum in Kyushu, Japan, which is close geographically, both areas have the species of Miscanthetea sinesis and Ericaceae in common. But Cheju Island has more abundant species and has higher ratio of appearance of alpine plants. The shrub communities of Cheju Island and Kyushu. Japan are identified as having a different rank over Alliance.

• Journal of Environmental Science International
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• v.20 no.4
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• pp.527-540
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• 2011

The investigation was made about distribution and ecological characteristics of Rhododendron mucronulatum var. mucronulatum, R. dauricum and R. schlippenbachii on Mt. Changbai in China. The Ericaceae plants are known to be highly ornamental and easy to cultivate. The results of investigations are like followings. The plant species diversity was the highest in habitats of R. mucronulatum var. mucronulatum, followed by those of R. schlippenbachii and R. dauricum. R. mucronulatum var. mucronulatum community was found in the northwest exposure areas of 300m in altitude. Corylus heterophylla, Carex humilis var. nana, Atractylodes japonica species also grew in the R. mucronulatum var. mucronulatum community. R. dauricum communities were widely distributed in the west exposure areas of 1226-1860m above sea level. R. schlippenbachii populations were found in areas of under 300m above sea level, which has dry soil. But humidity of air was relatively high in the place. Artemisia japonica, Lespedeza bicolor and Dactylis glomerata were found around the habitats of R. schlippenbachii. Phalanx type of plants were dominant near the habitats of Ericaceae plants as 61%. Further, there appeared higher plant life totalling to 72 taxa comprising 54 species, 16 varieties and 2 forma with 31 families and 59 genuses at the whole survey area. Among these, Compositae plants excellent in resistance to environment was surveyed the most, accounting for 30.0%.

• Journal of Oriental Neuropsychiatry
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• v.17 no.2
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• pp.75-89
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• 2006

Objective : This experiment was designed to investigate the effect of Rhododendron simsii Planch(RSP) on the Alzheimer's disease. Method : The effects of RSP on amyloid precursor proteins(APP), acetylcholinesterase (AChE), glial fibrillary acidic protein(GFAP) mRNA of PC-12 cell treated by amyloid ${\beta}$ protein$(A{\beta})$ and $IL-1{\beta}$, IL-6, $TNF-{\alpha}$ mRNA of THP-1 cell treated by lipopolysaccharide(LPS), AChE activity of PC-12 cell lysate treated by $A{\beta}$ and behavior of the memory deficit mice induced by scopolamine, and glucose, AChE in serum of the memory deficit mice induced by scopolamine were investigated, respectively. Result : 1. RSP suppressed APP, AChE, GFAP mRNA in PC-12 celt treated by $A{\beta}$. 2. RSP suppressed $IL-1{\beta}$, IL-6, $TNF-{\alpha}$ mRNA in THP-1 cell treated by LPS. 3. RSP suppressed AChE activity in cell lysate of PC-12 cell treated by $A{\beta}$. 4. RSP increased glucose and decreased AChE significantly in the serum of the memory deficit mice induced by scopolamine. 5. RSP group showed significantly inhibitory effect on the scopolamine-induced impairment of teaming and. memory in the experiment of Morris water maze. Conclusion : According to the above results, it is suggested that RSP might be usefully applied for prevention and treatment of Alzheimer's disease and memory deficit symptom.

• Korean Journal of Plant Resources
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• v.8 no.1
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• pp.41-46
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• 1995

This experiment was carried out to investigate the effects of temperature, light quality and gibberellic acid on the seed germination of Rhododendron weyrichii Max. Optimum temperature for germination was $20^{\circ}C$ at constant temperature, but the final germination rate at $15^{\circ}C$ was about the same with the rates were attained by alternating temperature under higher temperature such as $25^{\circ}C$ or $30^{\circ}C$. The germination rate was increased by yellow and red light treatments at $20^{\circ}C$, but green light treatment strongly inhibited seed germination at $25^{\circ}C$. Gibberellic acid substitutes light requirement for germination of R. weyrichii seeds.

• Research in Plant Disease
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• v.12 no.3
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• pp.284-286
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• 2006

Leaf gall was occurred on Rhododendron indicum(L.) Sweet[=Azalea indica L.] in a farmer's garden located in Geumsan-myon, and along the walk way of Gangju pond in Jeongchon-myon, Jinju, Korea. The infected leaves was deformed into very conspicuous, pale, fleshy shapeless galls. Basidia were fusiform, $3{\sim}5$ sterigma, and $8{\sim}35{\times}3{\sim}6{\mu}m$ in size. Basidiospores were musiform, straight or curved and $10{\sim}22{\times}3{\sim}5{\mu}m$ in size. The causal organism was identified as Exobasidium japonicum Shirai based on the mycological characteristics of the fungus and pathogenicity. This is the first report on the leaf gall of R. indicum caused by E. japonicum in Korea.

• Applied Biological Chemistry
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• v.39 no.6
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• pp.506-511
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• 1996

Six phenolic acids were isolated from Jindalrae flowers (Rhododendron mucronulatum Turcz.), an edible plant in Korea. These compounds were identified as chlorogenic acid, 3,5-O-dicaffeoylquinic acid, 4,5-O-dicaffeoylquinic acid, caffeic acid, ferulic acid, and p-coumaric acid on the basis of IR, UV, $^{1}H$ and $^{13}C$ NMR, FAB-MS, ES-MS and/or El-MS data. Chlorogenic acid (0.2 g) present in both ethyl acetate and ethyl ether fractions comprised up to 38.5% of the total phenolic acid amount (0.52 g) finally recovered by means of polyamide C-200 column chromatography, preparative TLC, recrystallization, and Sephadex LH-20 column chromatography The antioxidant activities were measured in an ethanol solution of linoleic acid in the presence of ferric thiocyanate. The antioxidant efficiency increased in the order of p-coumaric acid<${\alpha}-tocopherol$