• Current Research on Agriculture and Life Sciences
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• v.16
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• pp.84-95
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• 1998

Apple Marssonina blotch, caused by Diplocarpon mali, which has been increasing on apple trees and become one of the most serious diseases on apple trees in Korea since the begining of 1990's. In this study, ecology of Marssonina blotch including disease incidence and spore dispersals was surveyed from 1992 to 1995 in Kyungpook, and factors influencing the incidence of the disease were analyzed. Marssonina blotch began to occur on apple leaves in June and was observed commonly in most of apple orchards after August, and increased rapidly in September. The incidence of this disease was high at the year of low temperature and a lot of precipitation. The conidia discharge began to occur in May and continued to October, and the peak period of spore release was in August and usually more than 70% of total spore release of the year released from August to September. The incidence of the disease was high in the northern and mountain are as such as Yeongjoo, Chungsong, Andong, and relatively low in the southern areas such as Kunwi, Yongchon. Jonathan cultivar was the most susceptible to Marssonina blotch, and Jonagold, Sekaiichi was secondly susceptible and the next Fuji was more susceptible than Tsugaru. The incidence of the disease was relatively high in orchards which cultivation management of irrigation, drainage, air circulation, fertilization, and fungicide spraying were poor.

• Horticultural Science & Technology
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• v.35 no.3
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• pp.387-391
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• 2017

Kiwifruits introduced to Korea typically have green fruit flesh, yellow flesh, or yellow flesh with red coloration around the core. Here, we describe a new cultivar called 'Redvita', the first kiwifruit cultivar of Korea with yellow flesh and red coloration around the core. A conventional field cross was conducted in 2003, and permission for the final release of 'Redvita' was obtained in 2012. 'Redvita' originates from 'Red Princess', a maternal vine known for the red coloration in its flesh. The pollinizer is 'NHK0013' (IT233175), which blooms in early May. A principal feature of 'Redvita' is its high vitamin C content, which at an average of 140 mg per 100 g of fresh weight is 2 - 4 times higher than other commercial cultivars. The average fruit weight is 97 g; bigger than that of the control cultivar 'Hongyang'. 'Redvita' blooms in mid-May and is usually harvested in early to mid-October, approximately 150 - 160 days after anthesis. 'Redvita' produces 3 or 4 flowers per fruiting shoot, with no small lateral flowers, therefore does not need to be thinned before blooming for commercial production. The cultivar is acidulous because of a high titratable acidity content (about 1.5%), which is higher than other cultivars (less than 1.0%). 'Redvita' was registered with the Korean Seed and Variety Service in 2015 for plant variety protection rights (no. 5604).

• Korean Journal of Breeding Science
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• v.42 no.5
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• pp.534-539
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• 2010

'Hongro' is early-mid maturing cultivar with good quality like 'Tsugaru' and it has not preharvest drop. The CAX1 gene was introduced into Korean apple cultivar 'Hongro' by Agrobacterium tumefaciens LBA4404 harboring pBI121 to obtain transgenic apple with enhanced Ca level. The CAX1 gene playing the role of $H^+/Ca^{2+}$ transporter from Arabidopsis thaliana increases Ca concentration in several plants. Regenerated transgenic lines were confirmed by polymerase chain reaction (PCR) analysis and Southern blot analysis of genomic DNA for the existence of CAX1 gene. Southern blot analysis of 'Hongro' transformants showed that two putative transgenic lines were integrated with CAX1 gene in genomic DNA. The CAX1 comparative expression levels of two transgenic lines were higher than that of non-transformant evaluated by comparative quantification analysis using a real-time PCR. These two lines were multiplied in vitro, and micro-grafted on apple rootstocks 'M.9' in the isolated greenhouse. Since two years after micro-grafting, the fruits came into bearing. Compared to Ca level of the non-transgenic 'Hongro', that of the CAX1 transgenic 'Hongro' in the flesh and leaves was higher.

• Food Engineering Progress
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• v.21 no.4
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• pp.326-331
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• 2017

A cultivar (Malus domestica cv. Fuji) of apple was selected to make apple peel (AP) powder by three different powdering methods. Frozen AP was thawed and subsequently was dried or ground without drying. After AP was dried by hot-air drying at $60^{\circ}C$ or freeze-drying, the dried AP was ground using a conventional blender. Separately, the thawed AP was powered by using a cryogenic micro grinding technology (CMGT). The ground AP and three types of AP powder were extracted using deionized water, 20, 40, 60, 80, or 100% methanol, followed by vacuum evaporation. The total phenolics contents (TPC), total flavonoids contents (TFC), DPPH, and ABTS radical scavenging capacities of each extract were compared to determine an efficient powdering method. Lyophilized AP powder extract using 60% methanol showed the highest TPC and DPPH radical scavenging capacity. In contrast, 60% methanol extract of the powder by CMGT, resulting in the smallest particle, exhibited the highest TFC and ABTS radical scavenging capacity. This study suggests that the extraction yield of bioactive compounds from AP may be varied according to different powdering methods and that a new powdering process such as CMGT may be applicable to develop functional foods efficiently.

• Korean Journal of Agricultural and Forest Meteorology
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• v.16 no.1
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• pp.59-71
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• 2014

This study was conducted to find out the freezing hardness of apple tree as influenced by dwarfrootstocks, cultivars, and low temperature treatments. The dwarf-rootstocks used were M.9 and M.26, and three cultivars used were early-maturing 'Tsugaru', mid-maturing 'Hongro', and late-maturing 'Fuji'. Chilling temperatures were applied from $0^{\circ}C$ to $-40^{\circ}C$. Checking points of apple tree for freezing hardness were rootstock, trunk, feather, floral bud and foliar bud. Investigations were evaluated by the measure of water loss, electrolyte leaching, and sprouting. The results did not show the differences in water loss, electrolyte leaching, and sprouting by dwarf-rootstocks. Water loss of 'Fuji' was lower than that of 'Tsugaru' and 'Hongro', but sprouting ratio of 'Fuji' was higher than that of 'Tsugaru' and 'Hongro'. Water loss and electrolyte leaching increased as treated by lower temperature, while sprouting ratio decreased. In $-35^{\circ}C$ treatment, sprouting of rootstock and trunk part were higher than that of feather, while sprouting of floral bud was lower than that of foliar bud. Sprouting of bourse shoot at the accumulated low temperature in terms of $-10^{\circ}C$ per day was 100% in the 28 days, and sharply decreased about 50% in the 35 days. In conclusion, there were no differences in freezing hardness between M.9 and M.26, but freezing hardness of late-maturing cultivar was tended to stronger than that of early-maturing and mid-maturing cultivars. Freezing hardness of floral bud was extremely weak $-30^{\circ}C$.

• Korean Journal of Agricultural and Forest Meteorology
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• v.4 no.2
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• pp.114-118
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• 2002

This study was conducted to estimate the full bloom stage of the Fugi apple at e in different elevations at Chungju area. The lapse rate of air temperature related to the elevation in Chungiu area was calculated and applicated to estimate the full bloom stage of the Fugi apple cultivar at different elevations. The data far nine levels of elevations at 150, 250, 359, 555, 710 m with the direction of S-W in the Mt. Gyemyong and at 165, 255, 415, 545 m with the direction of N-W in the Mt. Nam were analyzed. The lapse rate range were 0.89$^{\circ}C$ per 100 m elevation in the Mt. Gyemyong and 0.74$^{\circ}C$ in the Mt. Nam respectively. The difference of full bloom stage different elevations was 4 to 5 days per 100 m and its range was from April 29th at 100 m to May 10th at 400 m.

• Korean Journal of Weed Science
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• v.30 no.4
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• pp.454-459
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• 2010

This study was conducted to investigate the phytotoxic reaction and the impact on the growth of apple fruit included the yield amount by misuse of non-selective herbicide, glufosinate-ammonium in apple field and for the study, 4 cultivars of apple were tested. The results showed that the highest phytotoxic degree was observed on Sansa-cultivar and then the degree was diminished on Tsugaru, Hongro and Fuji in order in the application year. In one year after application, the highest phytotoxic degree was showed on Fuji and then diminished on Tsugaru, Hongro and Sansa in order. However, in one year after application, the phytotoxic symptom was negligible in comparison with the degree in the year of application and the flowering and fruiting were reduced 30% only in Fuji, but in the other cultivars, the phytotoxic symptoms were not observed. Meanwhile, the residue of glufosinate-ammonium was below the detection limit as 0.04ppm in all tested cultivars and in 2years after application, the phytotoxic symptom was not observed in all cultivars of the apple.

• The Plant Pathology Journal
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• v.18 no.5
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• pp.259-265
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• 2002

Apple mosaic virus (ApMV), a member of the genus Ilarvirus, was detected and isolated from diseased 'Fuji' apple (Malus domestica) in Korea. The coat protein (CP) genes of two ApMV strains, denoted as ApMV-Kl and ApMV-K2, were amplified by using the reverse transcription and polymerase chain reaction (RT-PCR) and were analyzed thereafter. The objectives were to define the molecular variability of genomic information of ApMV found in Korea and to develop virus-derived resistant gene source for making virus-resistant trans-genic apple. RT-PCR amplicons for the APMVS were cloned and their nucleotide sequences were determined. The CPs of ApMV-Kl and ApMV-K2 consisted of 222 and 232 amino acid residues, respectively. The identities of the CPs of the two Korean APMVS were 93.1% and 85.6% at the nucleotide and amino acid sequences, respectively. The CP of ApMV-Kl showed 46.1-100% and 43.2-100% identities to eight different ApMV strains at the nucleotide and amino acid levels, respectively. When ApMV-PV32 strain was not included in the analysis, ApMV strains shared over 83.0% and 78.6% homologies at the nucleotide and amino acid levels, respectively. ApMV strains showed heterogeneity in CP size and sequence variability. Most of the amino acid residue differences were located at the N-termini of the strains of ApMV, whereas, the middle regions and C-termini were remarkably conserved. The APMVS were 17.(1-54.5% identical with three other species of the genus Ilarviyus. ApMV strains can be classified into three subgroups (subgroups I, II, and III) based on the phylogenetic analysis of CP gene in both nucleotide and amino acid levels. Interestingly, all the strains of subgroup I were isolated from apple plants, while the strains of subgroups II and III were originated from peach, hop, or pear, The results suggest that ApMV strains co-evolved with their host plants, which may have resulted in the CP heterogeneity.

• Journal of Bio-Environment Control
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• v.25 no.3
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• pp.184-192
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• 2016

This study was carried out to investigate the effect of temperature ($15{\sim}40^{\circ}C$) and the spraying plant growth regulators ($GA_{4+7}+BA$ and prohexadione-calcium) during full blooming on pollen germination and pollen tube growth of the commercial apple cultivars ('Fuji' and 'Tsugaru') and apple cultivars bred in Korea ('Chukwang', 'Gamhong', 'Hongan', 'Honggeum', 'Hongro', 'Hwahong', 'Hongso', 'Summer dream' and 'Sunhong'). Pollen germination and pollen tube growth were increased with increasing temperature from 15 to $25^{\circ}C$, but high temperature over $30^{\circ}C$ inhibit those. The apple cultivar bred in Korea that shows the highest value on pollen germination and pollen tube growth at over $30^{\circ}C$ was 'Sunhong'. The spraying $GA_{4+7}+BA$ increased pollen germination and pollen tube growth than control, but that effect was not show at $40^{\circ}C$. The spraying prohexadione-calcium was not affect to pollen germination and pollen tube growth. In conclusion, if the air temperature during full bloom of apple tree rises about $30{\sim}35^{\circ}C$, the spraying $GA_{4+7}+BA$ after artificial pollination will be good to increasing fruit set.

• Korean Journal of Agricultural Science
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• v.6 no.2
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• pp.119-124
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• 1979

In order to examine $SO_2$ injury to apple shoots, cutting shoots of five cultivars were exposed to 3 ppm $SO_2$ in vase life conditions. 1. The most sensitive cultivar to $SO_2$ was 'Rall's Genet', and 'Starking' was most tolerant among cultivars tested. 2. Ethylene production of shoots showed peak after 8 hours exposure, when visible injury was not appeared, and was decreased with increase in exposure time. 'Rall's Genet' showed slower decrease in ethylene production than other cultivars. 3. Chlorophyll a, b and a/b ratio were decreased in all cultivars after 40-hr exposures to 3 ppm $SO_2$ and greatly decreased in 'Rall's Genet' compared to other cultivars.