• Applied Biological Chemistry
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• v.23 no.3
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• pp.178-183
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• 1980

Citrus fruits harvested in 1979 were collected from markets scattered in Jeju and Seogwipo area on Jeju island and also from citrus orchards with five, ten, fifteen, twenty, and thirty years of cultivation history. Organophorous insecticides and organochloro acaricides in the pulp of fruits were analysed by gas liquid chromatograph. It was found that EPN and Kelthane were most significant residues found in the citrus fruits in terms of both level and frequency of occurrence. Among citrus fruits collected from various markets, EPN was detected in 28% of the fruits samples in the range of 0.009 to 0.025 ppm, while Kelthane, at lower level, was found in all citrus fruits in the range of trace to 0.007 ppm. Residue levels of citrus fruits from orchards of various cultivated periods, in general, confirmed those of the fruits collected from commercial markets. However, residues of Kelthane in the citrus fruits tended to increase with orchards having longer cultivation history.

• The Plant Pathology Journal
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• v.17 no.6
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• pp.382.4-382
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• 2001

• The Plant Pathology Journal
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• v.31 no.4
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• pp.343-349
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• 2015

Citrus canker caused by Xanthomonas citri subsp. citri (Xcc) is one of the most important bacterial diseases of citrus. Because citrus canker is not found in many countries including European Union and Australia, Xcc is strictly regulated in order to prevent its spread. In this study, the effects of X-irradiation on Xcc growth either in the suspension or on the surface of citrus fruits were investigated. The suspension containing $1{\times}10^7cfu/ml$ of Xcc was irradiated with different absorbed doses of X-irradiation ranging from 50 to 400 Gy. The results showed that Xcc was fully dead at 400 Gy of X-irradiation. To determine the effect of X-irradiation on quarantine, the Xcc-inoculated citrus fruits were irradiated with different X-ray doses at which Xcc was completely inhibited by an irradiation dose of 250 Gy. The $D_{10}$ value for Xcc on citrus fruits was found to be 97 Gy, indicating the possibility of direct application on citrus quarantine without any side sterilizer. Beside, presence of Xcc on the surface of asymptomatic citrus fruits obtained from citrus canker-infected orchards was noted. It indicated that the exporting citrus fruits need any treatment so that Xcc on the citrus fruits should be completely eliminated. Based on these results, ionizing radiation can be considered as an alternative method of eradicating Xcc for export of citrus fruits.

• Journal of Medicine and Life Science
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• v.15 no.1
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• pp.6-11
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• 2018

Previous studies have suggested that Citrus fruits might suppress the proliferation of various cancer cells. However, little is known about any specific ingredients in the extract of Citrus fruits to exert its anti-proliferative activity in cancer cells. The present study aimed to identify the active ingredients in Citrus fruits to suppress the proliferation of rat hepatocellular carcinoma cells. Among tested compounds, two polymethoxylated flavones (nobiletin and tangeritin) showed significant anti-proliferative activity whereas other compounds (synephrine, rutin, hesperidin) did not. Interestingly, nobiletin as well as tangeritin also decreased the protein amount of gluconeogenic enzymes, PEPCK and G6Pase. The possible involvement of gluconeogenic activity in the proliferation of hepatocellulacarcinoma cells are further to be investigated.

• Food Science and Biotechnology
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• v.14 no.4
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• pp.533-536
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• 2005

[ ${\beta}$-Cryptoxanthin ] contents were determined from Citrus unshiu Markovich fruits grown in a greenhouse and open field of Jeju Island, off the southern coast of Korea. In a greenhouse and open field, the ${\beta}$-cryptoxanthin content in the peel was greatly increased by harvesting citrus fruits in the late season from August through November. However, ${\beta}$-cryptoxanthin content in the flesh was gradually increased and was superior to that of the citrus fruits grown in a greenhouse. ${\beta}$-Cryptoxanthin was efficiently purified from the flesh of citrus fruits harvested in the late harvesting season in November. The ${\beta}$-cryptoxanthin contents in the peel and flesh of citrus fruits harvested from a greenhouse in November were 0.89 mg% and 0.35 mg%, respectively, and in that obtained from an open field were 1.12 mg% and 0.35 mg%, respectively.

• Mycobiology
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• v.28 no.3
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• pp.158-162
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• 2000

Twenty-three isolates of Fusarium spp. were obtained from decayed citrus fruits in the fields and storages in 1998-1999. Of them, six and five isolates belonged to F. proliferatum and F. moniliforme, respectively, which were the most common. F. solani and F. sambucinum had each two isolates, F. equiseti had one isolate and seven isolates were unidentified. They produced symptoms of two types in pathogenicity test: those with leathery, beige to light or dark brown, and sunken lesions without surface mycelium (type-1) and those with lesions covered with white, beige or pink surface mycelium (type-2). Four of six isolates identified to F. proliferatum and two unidentified isolates produced type-1 lesions, and all isolates identified to F. moniliforme, F. solani, F. sambucinum, F. equiseti and five unidentified isolates produced type-2 lesions.

• Journal of Radiation Industry
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• v.4 no.3
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• pp.215-219
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• 2010

We have subjected to gamma-irradiation to citrus buds and then grafted onto mature citrus tree. Mutant citrus branch lines have been induced. As a result of first selection, we found the several mutant lines showing interesting phenotypes such as higher sugar content. We have selected several branches showing good qualities such as higher sweetness and/or lower acidity. Some branch lines showed over $13^{\circ}Brix$ sugar content and below 0.9% acidity. Other mutant branch lines showed the changes of shape, size, peel thickness, and fiber contents or distribution of fruits. The results suggest that gamma-irradiation is an effective tool for induction of citrus mutant lines.

• Agribusiness and Information Management
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• v.6 no.1
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• pp.1-11
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• 2014

The purpose of this study is to develop the growth prediction model that can predict growth and development information influencing on the production of citrus fruits. The growth model was developed to predict the floral leaf ratio, number of fruit sets, fruit width, and overweight fruits depending on the main period of growth and development by considering the weather factors because the fruit production is influenced by weather depending on the growth and development period. To predict the outdoor-grown citrus fruit production, the investigation result for the standard farms is used as the basic data; in this study, we also understood that the influence of weather factors on the citrus fruit production based on the data from 2004 to 2013 of the outdoor-grown citrus fruit observation report in which the standard farms were targeted by the Agricultural Research Service and suggested the growth and development information prediction model with the weather information as an independent variable to build the observation model. The growth and development model for outdoor-grown citrus fruits was assumed by using the Ordinary Least Square method (OLS), and the developed growth prediction model can make a prediction in advance with the weather factors prior to the observation investigation for the citrus fruit production. To predict the growth and development information of the production of citrus fruits having a great ripple effect as a representative crop in Jeju agriculture, the prediction result regarding the production applying the weather factors depending on growth and development period could be applied usefully.

• Proceedings of the Plant Resources Society of Korea Conference
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• v.18 no.1
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• pp.41-51
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• 2005

We examined whether extracts from 14 local citrus spp. on Jeju Island (Korea) contained chemosensitizing activity that would increase the cytotoxic effect of vincristine(VCR) in drug-resistant cancer cells. We report that methanol extracts from fruits and flowers of some species had a chemosensitizing effect that reversed P-glycoprotein (Pgp)-mediated multidrug resistance (MDR). Using drug-sensitive AML-2/WT and drug-resistant AML-2/D100 in the absence of VCR in human acute myelogenous leukemia cells we found that fruit or flower extracts alone generally had low cytotoxicity $(IC_{50}>200\;{\mu}g/ml)$. In studies examining the effect of extracts on 120 ng/ml VCR cytotoxicity in drug-resistant AML-2/D100 cells, we found that immature fruit extracts had greater chemosensitizing activity than either extracts from mature fruit or flower. Of the 14 species examined, the immature fruit extract from Inchangkyool (Citrus ichangiensis) showed the hishest chemosensitizing index(CI) valus. Immature fruit extracts of Hongkyool(C. tachibana), Byungkyool(C. platymamma), Cheongkyool(C. nippokoreana) and Jinkyool (C. sunki) also strongly potentiated VCR cytotoxicity in AML-2/D100 cells. The chemosensitizing effect of peel extracts was 2-10-fold that of whole fruit extracts from Hongkyool (C. tachibana), Byungkyool (C. platymamma) and Inchangkyool (C. inchangiensis). The CI values for flower extracts were higher than those for mature fruit extracts, but lower than those for immature fruit extracts. These results indicate that immature citrus fruits contain compounds that do not exert their activity solely through cytotoxicity. In particular, Incahngkyool (C. inchangiensis), Byungkyool(C.platymamma), Cheongkyool(C. nippokoreana) and Hongkyool (C. tahibana) may be useful sources of chemosensitizing compounds.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.8
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• pp.392-402
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• 2018

Citrus fruits can be classified as field citrus, greenhouse citrus, citrus produced by rain proof cultivation and late-harvested citrus such as Hallabong, Chunhaehyang, and Jinjihyang according to cultivation method or variety in Jeju province of Korea. The consumption of late-harvested citrus has been increasing steadily since 1990 because the sugar content of the fruits is ordinary higher than field citrus. The cultivation land of citrus produced by rain proof cultivation has been also enlarged continuously aided by Korean government support program and quality increasing effect of this cultivation method. However, the cultivation land of field citrus has been decreasing since 2010. In spite of such a decrease of cultivation land, recently the price of field citrus rather declined according to increasing of yield per 10a. For the estimation and forecast of the long-term supply-demand model in the field citrus, we constructed a partial balance model for the individual field citrus and estimated individual equation in each item's model by using the econometric method. As a result of the production storage scenario analysis, the cultivation area is expected to store 5%(14.49ha), 10%(14.97ha). 15%(15.50ha) of citrus production in 2027. This study reviews the structure of storage, and storability in Jeju field citrus and suggest several policy implications.