• Korean Journal of Agricultural Science
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• v.41 no.4
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• pp.265-274
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• 2014

Physiological characteristics of two Korean golden kiwifruit cultivars, 'Halla Gold' and 'Haehyang', were compared to determine the storage potential of fruit. The soluble solid levels of the fruit were 8.9 and 6.9 oBrix in 'Halla Gold' and 'Haehyang' at harvest, respectively but increased up to 15.4 in 'Halla Gold' and 17.5 oBrix in 'Haehyang' after 2 months of storage. Major sugars were fructose and glucose, and sucrose content was relatively low regardless of cultivar. The edible quality of 'Haehyang' was better than 'Halla Gold' because of higher amount of sugars. Firmness of the fruits gradually decreased as the increase of storage period in 'Halla Gold' in both flesh and core tissue. Th firmness loss of 'Haehyang' fruit was faster in the first 2 months and then became slow. After 75 days of storage, the firmness of 'Haehyang' fruit was only 5.2% at harvest. Core tissue was soften enough to eat at ripe stage. Wall modifying enzyme activities including xylanase, ${\alpha}$-L-arabinofuranosi-dase and ${\beta}$-galactosidase were consistently higher in 'Haehyang' and the activity of pectate lyase was more increased than 'Halla Gold' after 2 months of storage. Respiration rate of 'Haehyang' was higher than 'Halla Gold' and further increased after 2 months of storage. Weight loss was much higher in 'Haehyang' which showed higher rate of the firmness loss. The storage potential of golden kiwifruit was estimated to be about 2 months for 'Haehyang' and 3 months for 'Halla Gold' when determined on the basis of the fruit firmness.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.4
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• pp.481-489
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• 2017

Kiwifruit wine was prepared with the domestic new cultivars 'Jecy Sweet' and 'Jecy Gold', and quality characteristics were investigated during fermentation with Saccharomyces bayanus Lalvin and Saccharomyces cerevisiae Fermivin and aging for 120 days at $15^{\circ}C$. Total acidities were 0.94% and 1.22% for 'Jecy Sweet' and 'Jecy Gold' at the beginning, respectively, and increased gradually during fermentation; highest acidities were 1.49% and 1.26%, respectively, on the 6th day of fermentation regardless of yeast strain. Alcohol content increased greatly from the 4th day of fermentation and was highest (10.2%) in 'Jecy Sweet' fermented by S. bayanus Lalvin, followed by 9.2% in 'Jecy Sweet' fermented by S. cerevisiae Fermivin and 9.4% in 'Jecy Gold' fermented by Lalvin and Fermivin on the 12th day of fermentation. Soluble solid content was $24.8^{\circ}Brix$ at the beginning and decreased gradually during fermentation. The lowest soluble solid content was $9.7^{\circ}Brix$ on the 6th day of fermentation regardless of kiwifruit cultivar and yeast strain. Total phenols in 'Jecy Sweet' (1,127 mg/L) were 1.32-fold higher than those in 'Jecy Gold' (848 mg/L) and decreased greatly until the 6th day of fermentation, after which they increased slightly until the 12th day of fermentation. During aging, total phenols increased until the 30th day and were maintained for 120 days. Quality characteristics of kiwifruit wines were similar between the two yeast strains but were different between kiwifruit cultivars. Contents of ethanol and total phenolics were higher in 'Jecy Sweet' wine than in 'Jecy Sweet' wine.

• The Plant Pathology Journal
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• v.32 no.6
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• pp.545-551
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• 2016

A bacterial pathogen, Pseudomonas syringae pv. actinidiae (Psa), is a causal agent of kiwifruit bacterial canker worldwide. Psa biovar 3 (Psa3) was first detected in 2011 at an orchard in Dodeok-myeon, Goheung-gun, Jeonnam Province in Korea. In this study, we present the results of an epidemiological study regarding Psa3 occurrence on kiwifruit orchards in Korea for the period of 2013 to 2015. Since the first detection of Psa3 in 2011, there was no further case reported by 2013. However, Psa3 was rapidly spreading to 33 orchards in 2014; except for three orchards in Sacheon-si, Gyeongnam Province, most cases were reported in Jeju Island. Entering 2015, bacterial canker by Psa3 became a pandemic in Korea, spreading to 72 orchards in Jeju Island, Jeonnam, and Gyeongnam Provinces. Our epidemiological study indicated that the first Psa3 incidence in 2011 might result from an introduction of Psa3 through imported seedlings from China in 2006. Apart from this, it was estimated that most Psa3 outbreaks from 2014 to 2015 were caused by pollens imported from New Zealand and China for artificial pollination. Most kiwifruit cultivars growing in Korea were infected with Psa3; yellow-fleshed cultivars (Yellow-king, Hort16A, Enza-gold, Zecy-gold, and Haegeum), red-fleshed cultivars (Hongyang and Enza-Red), green-fleshed cultivars (Hayward and Daeheung), and even a kiwiberry (Skinny-green). However, susceptibility to canker differed among cultivars; yellow- and red-fleshed cultivars showed much more severe symptoms compared to the green-fleshed cultivars of kiwifruit and a kiwiberry.

• Korean Journal of Plant Resources
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• v.24 no.5
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• pp.599-603
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• 2011

The incidence rates of postharvest fruit rots of four kiwifruit cultivars which were cultivated under rain-proof tunnel house at a same orchard were examined. Among them, 'Halla-Gold', 'Jecy-Gold' and 'Jecy-Sweet' were new cultivars bred in Korea. The disease incidence was varied with cultivars; 74.8%, 65.3%, 57.1% and 16.2% for 'Hayward', 'Halla-Gold', 'Jecy-Sweet' and 'Jecy-Gold' cultivars, respectively. Two hundred and eighteen isolates were obtained from diseased fruits and identified by mycological and molecular biological methods. Three fungi, Botryspheria dothidea, Diaphorthe actinidiae and Botrytis cinerea, were identified as pathogens of the postharvest fruit rots with detection rates of 95.4%, 4.6% and 2.3%, respectively.

• Research in Plant Disease
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• v.19 no.1
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• pp.1-6
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• 2013

Optimal spray time, interval and number of preventive fungicides against fruit rots of kiwifruit were investigated at the orchard which both green kiwifruit cultivar 'Hayward' and gold kiwifruit cultivar 'Hort16A' are cultivating side by side during 2009 and 2010 growing seasons in Jeju island, Korea. The highest control efficiency was obtained from benomyl WP and followed by thiophanate-methyl WP and carbendazim+diethofencarb WP. The control efficacies of the fungicides were much higher when applied onto the kiwifruit canopy after the flowering time than before the flowering time but thereafter their control efficiencies were decreased drastically according to delays of spray timing. With increasing spray numbers of the fungicides, the control efficacy increased. However, optimal spray time, interval and number of the preventive fungicides for the effective control of fruit rots of kiwifruit were determined as 4 time-spray schedule with 2-week-interval just after the flowering time on both 'Hayward' and 'Hort16A' cultivars.

• Research in Plant Disease
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• v.22 no.4
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• pp.276-283
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• 2016

Bacterial canker caused by Pseudomonas syringae pv. actinidiae (Psa) occurred at 202 kiwifruit orchards for the survey period of 2013-2016, of which Psa biovar 2 (Psa2) and Psa biovar 3 (Psa3) were detected at 73 and 129 kiwifruit orchards, respectively. The number of kiwifruit orchards infected by Psa3 in 2016 increased nearly two times compared to 2015. Psa3 was detected from all the kiwifruit cultivars except some kiwiberry cultivars growing in Korea. Yellow-fleshed cultivars Hort16A and Jecy-gold and red-fleshed cultivar Hongyang were highly susceptible to Psa3. Our epidemiological and random amplification of polymorphic DNA analyses indicated that the first Psa3 incidence on Hongyang orchard in Sacheon, Gyoungnam might result from an introduction of Psa3-contaminated pollens from China for artificial pollination in 2014 and recent outbreaks of Psa3 in Sacheon and Goseong, Gyoungnam in 2016 might be due to rapid spread of bacterial canker by secondary infection of Psa3 from Hongyang orchard to neighboring Jecy-gold and Hayward orchards.

• Horticultural Science & Technology
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• v.34 no.5
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• pp.755-760
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• 2016

In general, the storage life of hardy kiwifruit (Actinidia arguta) is approximately one month, even in cold storage, which is a limiting factor for its commercialization due to the short marketing period. This short shelf life is in contrast to those of green kiwifruit (A. deliciosa, 6 to 8 months) and gold kiwifruit (A. chinensis, 4 to 6 months). To increase the storage life of hardy kiwifruit, we performed a cross between A. arguta (a local collection, 'Hy2-1', female) and A. deliciosa ('Matua', male) at Wando station at the Fruit Research Institute of JARES, Korea in 1999. After the first selection in 2006, we clonally propagated the hybrid plants by grafting them onto A. arguta seedlings in Gwangyang and Haenam province, Korea. We performed the final selection of this cultivar in 2012 and applied for plant protection rights from the Korea Forest Research Institute in 2013. Several experimental orchards have been established for commercial production. 'Mansu' begins to flower on May 20 in Gwangyang. The horticultural maturity date in 'Mansu', when the soluble solid content reaches $7^{\circ}Bx$, is October 15, whereas that of the control variety ('Chiak') is October 5. The average fruit size of 'Mansu' is approximately 15 g. The soluble solid content of 'Mansu' is approximately 16 to $17^{\circ}Bx$ after ripening. The total yield of mature 'Mansu' vines is estimated to be 2.2 to 2.5 tons per 10a. The fruit firmness of 'Mansu' exceeded 1.5 kg/5 mmØ until 70 days after storage (at 0 and $1^{\circ}C$). Therefore, 'Mansu' fruits have much longer storability than the control. The cultivation and production of 'Mansu' may extend the marketing period for hardy kiwifruit.

• Horticultural Science & Technology
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• v.30 no.3
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• pp.334-337
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• 2012

A new promising kiwifruit, 'Halla Gold' variety with yellow flesh and being harvested in October, was developed at the Agricultural Research Center for Climate Change, National Institute of Horticultural and Herbal Science, Rural Development Administration, Korea in 2007. This variety was derived from the seedling population crossed between Actinidia chinensis cv. Golden Yellow and A. chinensis cv. Songongu in 1997. It was selected out of 2,971 seedlings. Characteristic trials were carried out from 2001 to 2003. After the selection, adaptability test was also conducted at kiwifruit orchards in Jeju Island from 2003 to 2007. Shoots of 'Halla Gold' sprout slightly stronger than those of 'Jecy Gold' but weaker than 'Hort16A' and the color of leaf is green. Fruit shape is oblong and fruit skin color is yellowish-dark green without hair. The average weight of fruit is 106.3 g. Fruit has a moderate size soft core, yellow pericarp, and fragile and juicy flesh. Soluble solids content is $14.7^{\circ}$ Brix and acidity is 1.4%. The harvesting time is about 10 days earlier than 'Jecy Gold' and about 20 days ahead of 'Hort16A'. The storage life is about 90 days at $2^{\circ}C$. This variety can be recommended for cultivating at low land area bellow 100 m sea level in Jeju Island or under shelter to prevent disease and cold injury.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.7
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• pp.859-865
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• 2007

The chemical components and antioxidative activity of Korean gold kiwifruit were investigated. The values of pH, soluble solid and total acidity were 4.43${\pm}$0.16, 17.01${\pm}$0.04$^{\circ}Brix$, and 0.082${\pm}$0.02%, respectively. Hunter L, a, and b values were 49.80${\pm}$0.24, -6.79${\pm}$0.02, and 19.72${\pm}$0.18 value, respectively. Proximate compositions were as follows; moisture 78.62${\pm}$2.26%, crude protein 1.34${\pm}$0.25%, crude lipid 0.70${\pm}$0.06%, crude fiber 1.99${\pm}$0.13%, crude ash 0.99${\pm}$0.26%, and carbohydrate 16.36${\pm}$1.23%, respectively. Mineral elements were K 265.86${\pm}$5.00, P 71.82${\pm}$29.18, and Ca 23.84${\pm}$2.10 mg%, respectively. Free sugar compositions were sucrose (1.04${\pm}$0.18%), glucose (2.17${\pm}$0.21%) and fructose (1.86${\pm}$0.11%). Amino acid contents of Korean gold kiwifruit was very rich in glutamic acid 86.51 ${\pm}$5.58 mg/100 g and deficient in tyrosine 15.00${\pm}$4.91 mg/100 g. Organic acid compositions were quinic acid (6.65${\pm}$0.21 mg/g), malic acid (1.62${\pm}$0.13 mg/g) and citric acid (4.82${\pm}$0.21 mg/g). Contents of ascorbic acid and total phenols were 0.27${\pm}$0.06 mg/g and 0.047${\pm}$0.002 mg/g, respectively. The DPPH radical scavenging activity and reducing power of the water extract from Korean gold kiwifruit was 86.87% and 1.96 at a concentration of 25 mg/mL. The water extract showed considerable antioxidative activity against linoleic acid autoxidation in a dose-dependent manner.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.3
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• pp.343-349
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• 2011

The chemical composition and antioxidative activity of kiwifruit varieties in Jeju, such as Jecy Gold (Actinidia chinensis var. 'Jecy Gold'), Halla Gold (A. chinensis var. 'Halla Gold'), Jecy Sweet (A. deliciosa var. 'Jecy Sweet') and Hwabuk 94 (A. deliciosa var. 'Hwabuk 94') were investigated. The crude protein, crude lipid, and pH showed no differences among variety and maturity whereas the moisture contents showed differences among the variety and maturity. Jecy Sweet in mature stage showed the highest values in soluble solid, crude protein, crude lipid, and crude ash. The changes in chemical components of kiwifruit by maturity stage were as follows: during ripening, the glucose and the fructose contents increased considerably with the decrease of sucrose content. Potassium, phosphorus, sodium, and magnesium were estimated as the major minerals in kiwifruit and Jecy Sweet contained the highest amounts of potassium and magnesium. At maturity stage, ascorbic, malic and lactic acid were increased with the decrease of citric acid content. The polyphenol contents were 26.81~56.10 ${\mu}g/g$ and 8.64~26.45 ${\mu}g/g$, respectively, in immature and mature fruits. During ripening, the polyphenol content was decreased. The DPPH radical scavenging activity of methanol extracts were 84.47~89.37% and 43.94~76.96% at 500 ppm, respectively, in immature and mature fruits. The immature varieties of kiwifruit have a high DPPH radical scavenging activity. Therefore the chemical composition and physiological activity of kiwifruit was affected by variety and maturity.