• Korean Journal of Agricultural and Forest Meteorology
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• v.16 no.4
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• pp.274-284
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• 2014

Crops and varieties are mostly affected by temperature, the amount of precipitation, and duration of sunshine. This study aims to identify the weather factors that directly influence to apple yield among the series of daily measured weather variables during growing seasons. In order to identify them, 1) a priori natural scientific knowledge with respect to the growth stage of apples and 2) pure statistical approaches to minimize bias due to the subject selection of variables are considered. Each result estimated by the Panel regression using fixed/random effect models is evaluated through suitability (i.e., Akaike information criterion and Bayesian information criterion) and predictability (i.e., mean absolute error, root mean square error, mean absolute percentage). The Panel data of apple yield and weather factors are collected from fifteen major producing areas of apples from 2006 to 2013 in Korea for the case study. The result shows that variable selection using factor analysis, which is one of the statistical approaches applied in the analysis, increases predictability and suitability most. It may imply that all the weather factors are important to predict apple yield if statistical problems, such as multicollinearity and lower degree of freedom due to too many explanatory variables used in the regression, can be controlled effectively. This may be because whole growth stages, such as germination, florescence, fruit setting, fatting, ripening, coloring, and harvesting, are affected by weather.

• Korean Journal of Agricultural Science
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• v.30 no.2
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• pp.115-122
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• 2003

This experiment was conducted to find the effect of a non-purine cytokinin, thidiazuron(TDZ), on the increase of berry size and fruit quality in 'Kyoho' grapes. For the comparison, the effect of forchlorfenuron(CPPU) was also examined The number of shot berries per cluster was significantly increased by the application of TDZ at 5 days after calyptra fall, resulting in the increase of cluster weight but no increase of each berry weight. The increase of berry weight was found when TDZ was applied at 10 to 15 days after calyptra fall. Gibberellin(GA $25mg{\cdot}L^{-1}$) was also effective on the increase of berry weight and the combined application of GA and TDZ further increased the berry weight. TDZ showed stronger effect on the increase of berry weight than CPPU at the same concentration. Berry ripening was more delayed at higher concentration of TDZ but no chemical injury was observed even at $20mg{\cdot}L^{-1}$. Results indicated that TDZ was effective on the quality improvement through berry weight increase and the recommended concentration TDZ for 'Kyoho' grapes was 5 to $10mg{\cdot}L^{-1}$.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.21 no.2
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• pp.73-78
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• 2015

Persimmons on the trees are often exposed to weather condition of cold temperature before harvest, which affects the fruit quality at harvest time and later storage. This study investigated the effect of the harvest season temperature on the storage quality of 'Fuyu' sweet persimmons. Monitoring the temperature changes in the orchard showed five times of cold temperature below the freezing temperature of persimmon, $-2.1^{\circ}C$, in the harvesting period between mid October and mid November with the lowest being as low as $-5.4^{\circ}C$. Among three different harvestings, the tertiary one at mid November showed decreased 'L' value and consistently high 'a' value of color index and high reduction in hardness during 150 days storage of fruits at $0^{\circ}C$ showing freeze-injured symptoms, compared to the first one at mid October and the second one at early November. The fruits of first harvest maintained consistently hard texture with increased 'a' color value probably due to postharvest ripening. The tertiary harvest exhibited increase in fructose and glucose contents and decrease in sucrose of the fruits, being very different from the first and secondary harvests which maintained constant level of all three free sugars. Mid November with possible sudden temperature drop is unsuitable period for harvesting sweet persimmons in the quality at harvest and later storage, and thus the harvest should be designed to be done before that time.

• Research in Plant Disease
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• v.25 no.4
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• pp.220-225
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• 2019

During the year 2018, the symptoms of bunch rot on Shine Muscat (Vitis vinifera L.) were observed in Kimcheon-si, Gyeongbuk province in Korea. The disease appears on the Shine Muscat as a black rot due to prolific fungal sporulation after it has invaded into the Shine Muscat which look completely empty and dryness. Colonies of these fungi are present on the Shine Muscat skin from fruit setting and increase in amount from early season to harvest, while become peak at ripening stage. To isolate the causal agent, small fragments (2 to 3 mm) of decayed tissue from the lesion margin were placed onto potato dextrose agar (PDA) plates. Fungal colonies on PDA produced dense white aerial mycelium and then covered with dark black conidial heads. These heads were large and radiate, and vesicles were globose (2.12-32.0×2.0-3.1 ㎛). Based on morphological and cultural characteristics, this fungus was identified as Aspergillus tubingensis. To confirm its identity, the internal transcribed spacer, β-tubulin, and RNA polymerase II was sequenced for molecular identification. BLAST search indicated 99% identity with A. tubingensis. The pathogenicity test on healthy grape of Shine Muscat produced bunch rot, as the original symptoms. To select effective fungicides for the control of brunch rot, an in vitro antifungal activity of seven fungicides were evaluated against the growth of A. tubingensis. Five fungicides (dipenoconazole, tebuconazole, metconazole, iminoctadine, and captan) exhibited significantly strong suppression of the mycelial growth of A. tubingensis.

• Journal of Plant Biotechnology
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• v.42 no.4
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• pp.290-297
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• 2015

Based on the place of its origin, pear tree (Pyrus spp.) is largely divided into European pears (P. communis, cultivated mainly in Europe and the U.S.) and Asian pears (P. pyrifolia, P. bretschneideri, and P. ussuriensis, distributed and grown in East Asian countries including China, Japan, and Korea). Most pear trees have 17 chromosomes (diploidy, 2n=2x=34). Their genetic studies and precise cultivar breeding are highly restricted by conditions such as self-incompatibility controlled by S-locus and juvenility as one major character of fruit crops. Genetic studies on Pyrus have been promoted by the development of various molecular markers. These markers are being utilized actively in various genetic studies, including genetic relationship analysis, genetic mapping, and QTL analysis. In addition, research on pear genetic linkage maps has been extended to studies for the identification of QTL for target traits such as disease resistance and genetic loci of useful traits. NGS technology has radically reduced sequencing expenses based on massive parallel reactions to enable high-capacity and high-efficiency. NGS based genome analyses have been completed for Chinese pear 'Danshansuli' and European pear 'Bartlett'. In Korea, GWAS for agricultural valuable traits such as floral structure, ripening, and total soluble contents have been conducted through resequencing. GBS has been performed for 'Whangkeumbae', 'Cheongsilri', and 'Minibae'.

• Korean Journal of Food Science and Technology
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• v.39 no.1
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• pp.7-13
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• 2007

The changes in phenolic compounds and pectin content were investigated during the growth of 3 cultivars (Hosui, Niitaka and Chuwhangbae) of Asian pear (Pyrus pyrifolria) fruits. The amounts of total phenolic compounds in peel, flesh and core was 20.61-22.98mg/g, 0.87-1.23mg/g and 6.39-37.96mg/g during early growth, respectively, and decreased with pear growth. Arbutin, chlorogenic acid and epicatechin were detected in each part of all three cultivars during early growth; of these, arbutin content was the highest. Caffeic acid, catechin and 4-hydroxymethyl benzoic acid were detected in the peel and core during the ripening process. The total pectin content in the flesh of Hosui, Niitaka, and Chuwhangbae cultivars decreased from 5.93mg/g, 5.99mg/g and 5.40mg/g to 1.07mg/g, 1.60mg/g and 1.63mg/g, respectively. Of the soluble pectins, the hydrochloric acid-soluble pectin content was the highest, 3.21-3.45mg/g, and decreased during growth.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2010.05a
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• pp.17-17
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• 2010

Ethylene, known as a stress hormone regulate wide developmental processes including germination, root hair initiation, root and shoot primordial formation and elongation, leaf and flower senescence and abscission, fruit ripening. The acceleration of ethylene biosynthesis in plant associated with environmental and biological stresses. 1-Aminocycloprophane-1-carboxlyate deaminase(ACCD) is an enzyme that cleaves ACC into and ammonia, a precursor of the plant hormone ethylene. Plant growth-promoting rhizobacteria (PGPR) having ACCD can decrease endogenous ACC level of tissue, resulting in reduced production of ethylene in plants. ACC deaminse was a key enzyme for protect stressed plants from injurious effects of ethylene. ACCD gene was encoded from Pseudomonas flourescens, PGPR and was cloned in Escherichia coli. We expressed the recombinant ACCD(rACCD) containing 357 amino acids with molecular weight 39 kDa that revealed by SDS-PAGE and western blot. The rACCD was purified by Ni-NTA purification system. The active form of rACCD having enzyme activity converted ACC to a-ketobutyrate. The optimal pH for ACC deaminase activity was pH 8.5, but no activity below pH 7.0 and a less severe tapering activity at base condition resulting in loss of activity at over pH 11. The optimal temperature of the enzyme was $30^{\circ}$ and a slightly less severe tapering activity at 15 - 30$^{\circ}$, but no activity over $35^{\circ}$. P. flourescens ACC deaminase has a highly conserved residue that plays in allowing substrate accessibility to the active sites. The enzymatic properties of this rACCD will provide an important reference for analysis of newly isolated ACCD and identification of newly isolated PGPR containing ACCD.

• Journal of Korean Society of Forest Science
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• v.96 no.6
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• pp.633-638
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• 2007

The Elaeagnus macrophylla is a stenoecious evergreen plant with nitrogen-fixing symbionts and its timing of fruit-ripening coincides with spring migration of many birds in southwestern Korea. To recognize bird species which eat fleshy fruits of the Elaeagnus macrophylla and to evaluate the effects of bird ingestion on seed germination and dispersal, we monitored birds and carried out germination experiments using its fruits and seeds from March to April 2007 at Hongdo Island, Jeonnam Province, Korea. As a result, eight species of birds including the Gray Starling (Sturnus cineraceus), the Brown-eared Bulbul (Hypsipetes amaurotis) and the Dusky Thrush (Turdus naumanni) ingested the fruits. Germination rate was enhanced but length of seed dormancy was instead shortened in ingested (collected from the feces of birds) and manually extracted seeds (obtained directly from the fruits) than in intact fruits collected directly from the plant. Moreover, the possible scale of seed dispersal by the frugivorous birds ranged up to 6.9 ha based on home ranges of starlings. Consequently, the Elaeagnus macrophylla supplies food resources for migratory birds, and the birds give the plant opportunities of new colonization. We suggest that this kind of interaction between the nitrogen-fixing plant and avian seed dispersers is applicable as a process of natural restoration in degraded coastal evergreen forests.

• Food Science and Preservation
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• v.10 no.4
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• pp.454-458
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• 2003

This study was conducted to enhance the quality and peach (Yumyung) by ozone treatment. The ozone concentration and treatment time in soaking of peach were 0.1, 0.3 and 0.5 ppm and 30 min respectively. Fruit brix degree, titratable acidity, hardness, colors values, and rotten rate were determined in ripening grade Yumyung peach and when fruits were placed at ambient temperuture(25$^{\circ}C$) during 20 days. No great difference occured between control group and all ozone treatment samples in the changes of brix degree, titratable acidity, hardness and color values at my sampling period. However, the rotten rate of ozone-treated peach stored at 25$^{\circ}C$ was lower than that of control sample. The orders of rotten rate in peaches stored for 15 days at 25$^{\circ}C$ were control products > 0.1ppm ozone-treated > 0.3ppm ozone-treated) 0.5ppm ozone-treated. Therefore, optimal renditions of Yumyung peach stored by ozone treatment at ambient temperature during 20 days were ozone concentration of 0.5ppm, treatment time of 30min, and ozone treatment frequency of four times.

• Journal of Bio-Environment Control
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• v.21 no.4
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• pp.404-410
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• 2012

This study was conducted to examine effects of harvest time (09:00 vs. 14:00), precooling at $4^{\circ}C$ vs. no precooling, and storage temperature (4 vs. $8^{\circ}C$) on the storage life of 'Maehyang' strawberry fruits for export. Fruits at a 60% ripe stage were harvested from a commercial greenhouse in Gyeongsangnamdo, Jinju on May 4, 2010. Fruits were precooled by a forced draft cooling for three hours, transported for about 30 minutes and then stored, immediately. Small precoolers set in the farm were used for precooling. Fruits were placed in constant temperature chamber (4 or $8^{\circ}C$) after packaging using PVC wrap and a cardboard box. Fruits were examined for their changes in weight, hardness, Hunter color values, soluble solids content (SSC), and incidence of gray mold (Botrytis cinerea) during storage at a two days interval from May 6 to May 14, 2010. Hardness and SSC decreased as the ripening stage progressed. The Hunter's 'L' and 'a' value of fruit color decreased as time passed. Also, fresh weight decreased during storage at all temperatures. Soft rot appeared on epidermal tissues and followed by gray mold. Incidence of gray mold was greater at $8^{\circ}C$ storage temperature than in $4^{\circ}C$ storage temperature. However, no difference by the harvested time and precooling. The results indicate that effectiveness for keeping the freshness was best achieved by precooling at $4^{\circ}C$ and storage at $4^{\circ}C$, respectively.