• Korean Journal of Environmental Agriculture
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• v.38 no.4
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• pp.314-320
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• 2019

BACKGROUND: As consumption of unripe mandarin increases, its cultivation has increased in open field cultivation areas. Because unripe mandarin must be harvested before ripening and color change, the optimum harvest time must be determined. This study investigated the effect of the harvest season on the yield of unripe fruit and biennial flowering of 'Miyagawa' satsuma mandarin. METHODS AND RESULTS: Two areas of unripe mandarin orchard were selected, and the yield, fruit growth, working time, and flowering of trees the following year were investigated. Fruit was harvested at 40, 60, 80, 100, and 120 days after full bloom and at general ripening. Fruit yield of unripe mandarin increased with later harvest time from 100^th to 120^th day except normal ripening. The next year, biennial occurred with normal ripening and harvesting, but not at the 120^th day after full bloom. At the 40^th day (earliest harvest time), summer and autumn shoots were present, but not after the 100^th day. The 40^th day required the most harvesting time; because the time gradually decreased with later harvest, the harvest time was shortest on the 120^th day, and general ripening occurred shortly after the 120^th day. CONCLUSION: Harvesting of unripe mandarin 100-120 days after full bloom was ideal to reduce harvesting time, enhance yield, and enable flowering the following year.

• Natural Product Sciences
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• v.17 no.4
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• pp.337-341
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• 2011

An HPLC (high-performance liquid chromatography)-PDA (photodiode array) detection method was established for the determination of naringin, hesperidin and neohesperidin in the fruit of Citrus paradisi and C. grandis. The flavonoids were separated in less than 20 min using an YMC RP 18 column with isocratic elution using acetonitrile and water (23 : 77, v/v) at a flow rate of 1 ml/min, and a PDA detector. The levels of naringin, hesperidin and neohesperidin were 1345.92, 950.62, and 2078.82 ${\mu}g/g$, respectively, in the peel, and 102.43, 59.13, and 86.68 ${\mu}g/g$, respectively, in the flesh of C. paradisi. In C. grandis, the levels of naringin, hesperidin and neohesperidin were 3530.56, 80.00, and 5.26 ${\mu}g/g$, respectively, in the peel, and 59.59, 7.43, and 38.41 ${\mu}g/g$, respectively, in the flesh. The total content was highest in the peel, reaching 0.44% and 0.36% in C. paradisi and C. grandis, respectively, while the flesh contained only 0.025% and 0.011%, respectively. Therefore, the peels of C. paradisi and C. grandis are necessary for the processing and utilization of flavonoids.

• Korean journal of applied entomology
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• v.39 no.4
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• pp.267-274
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• 2000

As the pest of the citrus in Cheju, 69 insect species and 5 animal species were investigated during 1996 to 1998. Of these, Panonychus citri, Phyllocnistis citrella, Aphis citricola, Aphis gossypii and Frankliniella occidentalis are major pests. Especially, F. occidentalis and Peridroma saucia are very important species because of increasing damage. The number of pests species injuring leaf, branch, fruit and flower of the citrus are 36, 16, 41 and 2 species respectively. The rate of damaged fruits by pests is 20.5% in 1997 and 18.6% in 1998 and the rate of bad quality fruits is 6.4% and 6.7% respectively.

• Korean Journal of Plant Resources
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• v.10 no.3
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• pp.213-220
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• 1997

The present study has been undertaken to characterize availability of citrus as a medicinal plant with antineoplastic property. The crude extracts from 40 species of fruits with 12 species of the local Citrus in Cheju island were evaluated on their potential activities against mouse P388 lymphocytic leukaemia in vitro. The percent cytotoxicity varied from 25.40 to 97.94% at a concentration of $100{\mu}g/mL$. Among 40 spp., 8 species showed high toxicity more than 90% against P388 cells and Cheongkyool(C. nippokoreana) exhibited the most cytotoxicity as 97.94%($IC_{50}=20.2{\mu}g/mL$). Nine varieties of C. junos were showed insiginicant cytotoxicity. In trifoliate orange, immature fruit was stronger than mature and peel extract showed higher cytotoxicity($IC_{50}=18{\mu}g/mL$) than the other tissues. Hexane fraction from methanol(MeOH) extract of trifoliate orange showed highly significant inhibition of cell growth($IC_{50}=3.9{\mu}g/mL$). In addition, its cytotoxicity increased remarkably from 3.95 to $0.40{\mu}g/mL$ as exposure time legthened. Cytotoxic activities of crude extracts were decreased considerably during a six months storage period. It was apparent that there is considerable variation in cytotoxicity, depending upon species, maturity and storage time of extracts. There was no meaningful cytotoxic difference between archicitrus and metacitrus in the genus Citrus.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.9
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• pp.1345-1350
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• 2013

The objective of this study was to evaluate the effect of extraction methods on the antioxidant activity of Citrus unshiu pomace. For this purpose, two kinds of citrus pomace (CP)s, whole fruit CP and pulp CP, were used for preparing the extracts with hot water or 70% ethanol. It is well-known fact that whole fruit CP has more calories and carbohydrates, although moisture content is higher in pulp CP. Further, whole fruit CP extracts have higher levels of total phenolic contents compared to CP extracts. In addition, DPPH and alkyl radical scavenging activities were also higher in whole fruit CP, especially in ethanolic extracts. Our results based on liquid chromatography-mass spectrometer showed that 70% ethanolic extract of whole fruit CP has the maximum levels of nobiletin and tangeretin contents. The levels of naringin, which is known as an antioxidant flavonoid, was determined only in the 70% ethanolic extract of whole fruit CP. This result, however, is consistent with the observed DPPH and alkyl radical scavenging activities. We had also performed a gas chromatography analysis that showed all the four extracts contained the compound hydroxymethyl furfural. Significantly, this compound has been reported to have antioxidant activity. Taken together, findings of this study indicate that ethanolic extraction of whole fruit CP is a good source of antioxidant compounds and hence the same could be utilized as an important method to obtain such beneficial compounds on an industrial scale.

• Korean Journal of Environmental Agriculture
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• v.32 no.4
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• pp.343-347
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• 2013

BACKGROUND: Control of alternate bearing satsuma mandarin in Jeju is very important to maintain the optimum price of fruit and get the sustainable income of farmers. Unlike orange, Satsuma mandarin is well known to sensitive on alternate bearing. We carried out the experiment to know the effect of foliar application of $GA_3$ on the flowering and fruit quality of satsuma mandarin (C. unshiu Marc. cv. Miyagawa). METHODS AND RESULTS: To experiment, the treatments consist of control, different concentration of $GA_3$ (25, 50 and 100 mg/L), machine oil emulsion 100 times and mixture of various concentration of $GA_3$ (25 and 50 mg/L) with machine oil emulsion 100 times which it was applied on 15 year-old Miyagawa satsuma mandarin at December 29, 2011. Foliar application of $GA_3$ in winter reduced the flowering of satsuma mandarin. Flower-leaf ratio was significantly reduced at 100 mg/L $GA_3$, while no differences observed in low concentration of $GA_3$ (25 and 50 mg/L). However, it was significantly decreased to 0.19 in application of $GA_3$ 25 and 50 mg/L with machine oil emulsion 100 times mixture. Number of leaves per fruit was significantly increased as foliar application of $GA_3$ also it reduced the fruits remarkably. Soluble solid contents and Hunter's a of peel color ratio showed no difference among $GA_3$ single treatments, but it was reduced in $GA_3$ 25 and 50 mg/L with machine oil emulsion 100 times mixtures significantly. From the results, it has been found that higher $GA_3$ concentration can reduce the number of flowers on the alternate bearing of satsuma mandarin. However, it was found that lower concentration of $GA_3$ with machine oil emulsion mixture 100 times can reduce flowering. CONCLUSION(S): The foliar application of $GA_3$ (100 mg/L) can alleviate alternate beraring. Also, mixture of lower concentration of $GA_3$ with machine oil emulsion 100 times can retard flowering more significantly while it needs further confirmation.

• Korean Journal of Organic Agriculture
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• v.23 no.1
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• pp.77-89
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• 2015

133 Species of medicinal plants were used for the development of natural agrichemicals with anti-microbial activity against Acidovorax avenae subsp. citrulli, a pathogen of bacterial fruit blotch in watermelon. The MeOH-extracts of these medicinal plants were examined for anti-microbial activity by bioassay. The MeOH-extract of Citrus unshiu Markovich had the strongest antibacterial activity against Acidovorax avenae subsp. citrulli. To identify anti-microbial compounds from Citrus unshiu Markovich, solvent-fractionation was used. The fraction of hexane, which showing the highest value of anti-microbial activity, was analyzed by GC-MS. Each mass spectra, corresponding to each peak of chromatogram, was compared to mass database of Wiley library. As a result, d-Limonene, ${\gamma}$-terpinene, ${\beta}$-linalool, terpineol, palmitic acid, 9,12-octadecadienoic acid, Linolenic acid, and stigmasterol were identified. Among them, d-Limonene, ${\gamma}$-terpinene, ${\beta}$-linalool, and terpineol confirmed to be shown the anti-microbial activity by bioassay. Especially, d-Limonene and ${\gamma}$-terpinene found to have strong activity. In conclusion, we thought d-limonene and ${\gamma}$-terpinene from Citrus unshiu Markovich. Latin, had anti-microbial activity against Acidovorax avenae subsp. citrulli and could be candidates for the control agents for the control of bacterial fruit blotch in watermelon.

• Korean journal of applied entomology
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• v.48 no.4
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• pp.535-539
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• 2009

This study was conducted to identify plant-parasitic nematodes and determine the distribution pattern of the nematode species in citrus fruit orchards in Korea from April to August, 2008. Plant-parasitic nematodes were found in 139 among 178 soil samples. Tylenchulus semipenetrans was collected from 85 out of 94 Citrus unshiu orchards examined (90.4%). C. junos orchards infested with T. semipenetrans were 60 out of 84 (71.4%). However, proportion of dominant species between the two was different. At domestic Citrus orchards, it proved that T. semipenetrans was the most important plant-parasitic nematode from this study. The overall frequency of the plant-parasitic nematodes was positively correlated with the cultivation years. More alkaline soils tended to harbor more T. semipenetrans. However the correlation coefficient between the two was very low.

• Korean Journal of Medicinal Crop Science
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• v.21 no.6
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• pp.493-497
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• 2013

This study was designed to analyze the chemical composition of essential oil in 'Shiranuhi' immature fruit and to test their biological activities. 'Shiranuhi' immature essential oils (SIEO) were obtained by steam distillation from fruits collected from Jeju Island and were analyzed using gas chromatograph (GC)-flame ionization detectors (FID) and GC-MS. Fourteen components were identified in the essential oil. Limonene (75.21%) and terpineol (8.68%) were the major components in SIEO. Since acne vulgaris is the combined result of a bacterial infection and the inflammatory response to that infection, we examined whether SIEO possessed antibacterial against skin pathogens. As a result, SIEO showed excellent antibacterial activities against drug-susceptible and -resistant Propionibacterium acnes and Staphylococcus epidermidis, which are acne-causing bacteria. In this study, SIEO was examined on DPPH radical scavenging activities, which showed moderate antioxidant activity ($SC_{50}$, $15.36{\mu}L/mL$). In order to determined whether SIEO can be safely applied to human skin, the cytotoxicity effects of SIEO were determined by colorimetric MTT assays in normal human fibroblasts and keratinocyte HaCaT cells. They exhibited low cytotoxicity at $0.5{\mu}L/mL$ in both celllines. Based on these results, we suggest the possibility that essential oil of 'Shiranuhi' maybe considered as an antibacterial and antioxidant agent.

• Journal of Biosystems Engineering
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• v.43 no.4
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• pp.401-409
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• 2018

Decay of fruit is one of the greatest issues in fruit storage. Purpose: In this study, citrus sterilization was performed to evaluate a dry sterilization method using an atmospheric-pressure nonthermal plasma treatment based on a dielectric-barrier discharge technique. Methods: Citrus samples were stored under four different environmental conditions as follows: group A had cold storage with plasma treatment with a temperature of $6.2{\pm}1.0^{\circ}C$ and relative humidity (RH) of $93.4{\pm}8.2%$, group B had ambient-temperature storage with $22.9{\pm}2.3^{\circ}C$ and $82.1{\pm}4.5%$ RH, group C ambient-temperature storage with plasma treatment with $25.3{\pm}2.2^{\circ}C$ and $90.0{\pm}2.8%$ RH, and group D had cold storage with $5.7{\pm}1.0^{\circ}C$ and $93.4{\pm}6.5%$ RH. Results: As a result of citrus surface sterilization by plasma treatment, treatment groups A and C together showed an average of 16.1 CFU/mL of mold colonies, while control groups B and D showed an average of $2.2{\times}10^2CFU/mL$ or approximately 13 times greater than the treatment groups. Regarding the mean concentration of aerobic bacteria colonies, the treatment groups (A and C) and control groups (B and D) showed an average of 7.1 CFU/mL and $1.9{\times}10^3CFU/mL$, respectively. This is approximately a 270-fold difference in the concentration of pathogen colonies between treatment and control groups. Conclusions: The results showed the potential of nonthermal plasma treatment for citrus storage in enhancing storage duration and quality preservation.