• Mycobiology
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• v.43 no.3
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• pp.354-359
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• 2015

Blossom blight in strawberry was first observed in a green house in Nonsan, Damyang, and Geochang areas of Korea, between early January to April of 2012. Disease symptoms started as a grey fungus formed on the stigma, which led to the blossom blight and eventually to black rot and necrosis of the entire flower. We isolated the fungi purely from the infected pistils and maintained them on potato dextrose agar (PDA) slants. To test Koch's postulates, we inoculated the fungi and found that all of the isolates caused disease symptoms in the flower of strawberry cultivars (Seolhyang, Maehyang, and Kumhyang). The isolates on PDA had a velvet-like appearance, and their color ranged between olivaceous-brown and smoky-grey to olive and almost black. The intercalary conidia of the isolates were elliptical to limoniform, with sizes ranging from $5.0{\sim}10.5{\times}2.5{\sim}3.0{\mu}m$ to $4.0{\sim}7.5{\times}2.0{\sim}3.0{\mu}m$, respectively. The secondary ramoconidia of these isolates were 0- or 1-septate, with sizes ranging betweem $10.0{\sim}15.0{\times}2.5{\sim}3.7{\mu}m$ and $8.7{\sim}11.2{\times}2.5{\sim}3.2{\mu}m$, respectively. A combined sequence analysis of the internal transcribed spacer regions, partial actin (ACT), and translation elongation factor 1-alpha (TEF) genes revealed that the strawberry isolates belonged to two groups of authentic strains, Cladosporium cladosporioides and C. tenuissimum. Based on these results, we identified the pathogens causing blossom blight in strawberries in Korea as being C. cladosporioides and C. tenuissimum.

• Korean Journal of Agricultural Science
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• v.47 no.4
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• pp.753-767
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• 2020

The commercial value of strawberries is affected by various factors such as their shape, size and color. Among them, size determined by weight is one of the main factors determining the quality grade of strawberries. In this study, image technology was developed to predict the weight of strawberries using the shape characteristics of strawberry cultivars. For realtime weight measurements of strawberries in transport, an image measurement system was developed for weight prediction with a charge coupled device (CCD) color camera and a conveyor belt. A strawberry weight prediction algorithm was developed for three cultivars, Maehyang, Sulhyang, and Ssanta, using the number of pixels in the pulp portion that measured the strawberry weight. The discrimination accuracy (R2) of the weight prediction models of the Maeyang, Sulhyang and Santa cultivars was 0.9531, 0.951 and 0.9432, respectively. The discriminative accuracy (R2) and measurement error (RMSE) of the integrated weight prediction model of the three cultivars were 0.958 and 1.454 g, respectively. These results show that the 2D imaging technology considering the shape characteristics of strawberries has the potential to predict the weight of strawberries.

• Journal of Bio-Environment Control
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• v.28 no.4
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• pp.429-437
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• 2019

This study was conducted to examine the effect of humidification and shading during cutting propagation on growth and development of strawberry (Fragaria x ananassa Duch.) 'Maehyang' plants at a propagation stage. The runner cuttings were stuck on Nov. 23, 2017 in propagation benches set in a Venlo-type glasshouse. Four shading treatments, no shading (control, C), 55% shading with white lawn (W55), 55% black shading net (B55), or 100% black plastic film (B100) with either an intermittent fog system (H) or without fog system. The shading and fog systems were removed 2 weeks after sticking of strawberry cuttings. A nutrient solution for strawberry, which was developed by Yamazaki, was supplied once a day with electrical conductivity (EC) $1.6dS{\cdot}m^{-1}$ and pH 5.8. Growth parameters such as plant height, longest root, crown diameter, leaf chlorophyll, leaf area and fresh and dry weight were measured at 7 days and 26 days after sticking. There was no significant difference in growth of above-aerial part of strawberry. The overall growth of the strawberry roots was better grew by providing fog than that not provide fog. The root fresh weight and root dry weight after 26 days after sticking of strawberry cutting was the best in the treatment that provided fog system without shading (CH). The longest root after 26 days after sticking of strawberry cutting was the best in the treatments that provided fog system with either 55% white lawn (W55H) and 55% black shading net (B55H). These results suggest that morphogenesis of these plants were affected by humidification and shading types. In a broader perspective, these results can be used to optimize studies of other crops grown from cuttings.

• Journal of Bio-Environment Control
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• v.29 no.3
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• pp.231-238
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• 2020

Strawberry (Fragaria × ananassa Duch.), a herbaceous perennial crop, is a popular fruit crop with high economical and nutritive values. This study was conducted to investigate the effect of the runner training angle (RTA) on the length of internodes and number of runners produced in strawberry 'Seolhyang' and 'Maehyang' in an attempt to achieve a higher production rate of runner plants and increase the propagation efficiency. Runners were trained for 30 days to grow at an angle of 0° (vertically upward), 45°, 90° (horizontal), 135°, or 180° (hanging down) from the upward vertical axis. The experiment was carried out in a glasshouse with 29/20℃ day/night temperatures, an average light intensity of 450 μmol·m^-2·s^-1 PPFD coming from the sun, and a natural photoperiod of 12 hours. For both 'Seolhyang' and 'Maehyang', the RTA affected number and length of runners, and number and fresh and dry weights of runner plants. Training at an angle of 135° or 180° shortened length of runners and internodes in 'Seolhyang'. These RTAs also produced runner plants with the lowest fresh and dry weights in both cultivars. The RTA did not affect the runner diameter, but affected the runner morphology in both cultivars. As compared to a RTA of 135°, a 180° RTA increased number of runner plants produced, making it the most proliferative RTA.

• Journal of Bio-Environment Control
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• v.26 no.3
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• pp.227-234
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• 2017

This study aimed to investigate the nutrient solution developed by based on nutrient-water absorption rate of strawberry 'Maehyang' by comparing growth and yield for 8 months with 5 kinds of nutrient solution with different ion composition. Strawberry plants were planted at elevated bed and supplied with five kinds of nutrient solutions (RDA), Yamazaki, PBG, University of Seoul (UOS) and NewUOS from one month onwards. Five types of nutrient solution were supplied to the strawberry plants associated with EC $1.0dS{\cdot}m^{-1}$, pH 6.0, $150{\sim}300mL{\cdot}plant^{-1}$ per day. At 60 days after planting, leaf width and leaf petiole of the strawberry plants showed significant differences among nutrient solution types and photosynthesis was higher in RDA and NewUOS nutrient solution and lower in PBG nutrient solution. The EC of the drainage on vegetative growth stage was $0.7{\sim}0.8dS{\cdot}m^{-1}$, which is lower than the supplied EC level, and to $1.0-1.2dS{\cdot}m^{-1}$, afterwards. The pH of the drainage was higher in Yamzaki solution as 6.2~6.8, while the pH of the UOS nutrient solution was lower in 5.1~5.2. Nitrate content was most absorbed in vegetative growth stage and after flower clusters development. The potassium uptake was highest at the NewUOS followed by UOS and Yamazaki nutrient solution. At six months after -planting fresh weight and dry weight of shoot and root were higher in UOS and NewUOS nutrient solution than other nutrient solutions, and the dry matter ratio was lower at 43.5% in Yamazaki nutrient solution and 30.6% in NewUOS nutrient solution than other solutions. Length, width, weight, and sugar content of the strawberries harvested from December to February were unaffected by treatment, but yield was higher in NewUOS nutrient solution due to increasing fruit number and average weight. From March to May, number of fruit was higher in Yamazaki nutrient solution. In conclusion, there was no difference in the growth of 'Maehyang' when 5 nutrient solutions were grown under hydroponics. But in order to improve the marketability, the NewUOS nutrient solution is appropriate to use from planting to February and it is suitable to use Yamazaki nutrient solution after March when temperature is high and the amount of fruit set per inflorescence.

• Korean Journal of Plant Resources
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• v.31 no.1
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• pp.90-94
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• 2018

The 'Hongsil' strawberry ($Fragaria{\times}ananassa$ Duch.) is a new cultivar released by Gyeongsangnam-do Agricultural Research & Extension Services in 2015. This cultivar originated from a 2011 cross between '802a312' and 'Okmae' and exhibited suitable fruit characteristics for export due to the high soluble solids content and firmness of the fruit. The breeding line '1116-74-15' was selected as an elite line after examining its characteristics and productivity from 2013 to 2014. A field trial of this line was conducted on a farm in 2015, and it was registered as 'Hongsil' thereafter. The 'Hongsil' strawberry demonstrates intermediate plant type and moderate vigor in growth. It is suitable for forcing culture due to its early flower bud differentiation and low chilling requirement. The soluble solids content of 'Hongsil' is $10.0^{\circ}Brix$, which is approximately $0.4^{\circ}Brix$ higher than that of 'Seolhyang' The Fruit firmness of 'Hongsil' is $13.1g{\cdot}mm^{-2}$, similar to that of 'Maehyang'. Fruits of 'Hongsil' are long conical having a red skin color and marketable yield is $4,269kg{\cdot}10a^{-1}$ which is 16% higher than that of 'Maehyang'. The 'Hongsil' cultivar is sensitive to powdery mildew, and it therefore warrants further investigation regarding disease control.

• Journal of Bio-Environment Control
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• v.21 no.4
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• pp.385-391
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• 2012

This study was conducted to investigate the effects of the runner cutting time on the growth and yield of strawberry (Fragaria ${\times}$ ananassa cv. Maehyang and Seolhyang) during nursery period of two consecutive years (2009 and 2010). Strawberry runners which connected from mother plants to daughter plants were cut 30, 20, 10 and 5 days before transplanting day (11 Sep. 2009 and 10 Sep. 2010). When runner cutting time delayed, more nutrition was supplied to the daughter plant until late nursery period. It showed that there was a tendency to increase the fresh weight, crown diameter and leaf chlorophyll content. On the other hand, when the runner was cut earlier, the growth of underground part such as root weight was improved. Irrigation demand increased to 29.7% in case of runner cutting from mother plant compared with runner non-cutting treatment. In addition, infection ratio of anthracnose through runner part was 37.6% higher in case of runner cutting than that of runner non-cutting treatment. After transplanting, budding and flowering period were delayed up to 2 or 3 days because of late runner cutting. But there was no significant difference in marketable fruit yield among runner cutting times. It is recommended to conduct runner cutting 5 or 10 days before transplanting for reducing the occurrence of anthracnose.

• The Plant Pathology Journal
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• v.22 no.3
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• pp.222-229
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• 2006

Twenty-two isolates of Fusarium oxysporum f. sp. fragariae were obtained from diseased strawberry plants and their characteristics were investigated by vegetative compatibility group (VCG), random amplified polymorphic DNA (RAPD), and pathogenicity. Three major VCGs (A, B, and C) and one incompatible group were identified by nitrate reductase complementation test. The virulence pattern of the 22 isolates was studied in relation to four cultivars including Dochiodome, Red-pearl, Maehyang and Akihime. RAPD markers were used to determine genetic relationship, and created three major clusters among the 22 isolates of F. oxysporum f. sp. fragariae. Isolates belong to VCG-C were strongly pathogenic, and relatively high correlation was existed among VCG and RAPD, and virulence. In addition, VCG and RAPD pattern between pathogenic and non-pathogenic isolates were distinctly different.

• Korean Journal of Food Science and Technology
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• v.38 no.5
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• pp.642-647
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• 2006

Yeast selection and the sterilization methods of strawberry juice were optimized for making strawberry wine. In addition, changes in the physicochemical characteristics of the wine during its fermentation were estimated. Maehyang and Yukbo cultivars of strawberry were tested for wine making; they contained 9.8 and 9.3% soluble solids and 0.59 and 0.58% titratable acidities, respectively. Among six yeasts tested, the Wg-15 and Sc-51 strains were selected based on the alcohol yield in the strawberry wine. Alcohol and soluble solid contents following heat treatment ($85^{\circ}C$, 10 min) or $K_2S_2O_5$ (200 ppm) treatment for sterilization were 7.10-7.20% and 5.60-5.80%, respectively, and no differences were observed between the Wg-15 and the Sc-51 strains. However, the flavor of wine produced following heat treatment was slightly better than that following $K_2S_2O_5$ treatment. The greatest amounts of alcohol were produced after 2 days of fermentation at $26^{\circ}C$. The alcohol content in wines produced with 12, 14, and 16% sugar content in the initial stages were 5.1, 6.0-6.2, and 7.5-7.7%, and the soluble solid contents were 3.9-4.3, 4.1-4.3, and 5.0-5.3%, respectively; no significant differences were observed between the Wg-15 and the Sc-51 yeast strains. For making strawberry wine, we proposed that the sugar content of Maehyang or Yukbo cultivars be adjusted to 16% soluble solids in the initial stages with heat treated at $85^{\circ}C$ for 10 min and fermentation with the Wg-15 or Sc-51 yeast strains at $26^{\circ}C$ for 8 days.

• Journal of Bio-Environment Control
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• v.30 no.1
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• pp.56-64
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• 2021

This study was conducted to examine the effect by different types and concentrations of auxin on the rooting and growth of strawberry (Fragaria × ananassa Duch. cv. Maehyang) cuttings in the greenhouse. The NAD (1-naphthylacetamide), IBA (indole-3-butyric acid), and IAA (3-indoleacetic acid) were applied with a 1 hour soaking as 50, 100, 150, and 200 mg·L-1, respectively. The non-treatment was set as the control. The cuttings of strawberry were transplanted in the strawberry seedling tray filled with coir medium on June 4, 2020. The humidification was carried out for 2 weeks. The average relative humidity, daytime temperature, and nighttime temperature inside the humidification tunnel was 63.4 ± 15%, 29.3 ± 5℃, and 16.2 ± 5℃, respectively. There was no significant difference in rooting rate on the control, IBA, and IAA treatments. However, significantly low rooting rates were observed in NAD treatments. The survival rates were significantly higher in the control and IBA with 50 mg·L-1 than in other treatments. The number of leaves was the highest in IBA with 100 mg·L-1. The root length was the longest in the control. More number of roots were counted in IAA with 100 and 150 mg·L-1. The dry weight of root was the heaviest in the control. The total root length, root surface, number of root tips, and number of root forks were significantly higher in the control. As a result, control, IAA, and IBA showed similar shoot and root growth. However, NAD showed the worst root and shoot growth. Consequently, compared with IAA and IBA, NAD was not appropriate plant growth regulator of rooting for cutting propagated strawberries.