• Research in Plant Disease
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• v.24 no.3
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• pp.193-201
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• 2018

Pectobacterium carotovorum subsp. carotovorum (Pcc) causes bacterial soft rot on a wide range of crops worldwide, especially in countries with warm and humid climates. This study was conducted to establish an efficient screening method for resistant cultivars of radish (Raphanus sativus) to bacterial soft rot. Resistance degrees of 60 commercial radish cultivars to the Pcc KACC 10421 isolate were investigated. For further study, six radish cultivars (Awooriwoldong, YR Championyeolmu, Jeonmuhumu, Bitgoeunyeolmu, Sunbongaltari, Housecheongok) showing different level of resistance to the bacterium were selected. The development of bacterial soft rot on the cultivars was tested according to several conditions such as incubation temperature, seedling stage of radish, inoculum concentration to develop the disease. On the basis of the results, we suggest that an efficient screening method for resistant radish to Pcc is to inoculate twenty-day-old seedlings with a bacterial suspension of Pcc at a concentration of $8{\times}10^5cfu/ml$ and then to cultivate the plants in a growth room at $25^{\circ}C$ and 80% RH with 12-hour light per day.

• Horticultural Science & Technology
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• v.31 no.1
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• pp.128-132
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• 2013

A new pink gerbera (Gerbera hybrida Hort.) cultivar 'Party Time' was developed from a cross between 'Hope' and 'Sunnyeo', followed by seedling and line selections at the Flower Research Institute of Gyeongnam Agricultural Research and Extension Services (GARES) in 2007. Detailed characteristics of the new cultivar were evaluated from 2005 to 2007. 'Party Time' has semi-double type large flowers in a good harmony with pink (RHS, 65-C) ray floret and brown center. It has a good, stable flower shape and strong peduncles, and its vase life was 12.7 days. The average flower yield of 'Party Time' was about 47.3 stems per plant a year in greenhouse yield trails carried out 2005 to 2007. 'Party Time' (Grant No. 2691) was registered to the Korea Seed and Variety Service (KSVS) for commercialization in 2009.

• Horticultural Science & Technology
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• v.18 no.1
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• pp.33-38
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• 2000

This study was conducted in an effort to meet the need for domestic production of hydroponic media and for medium development using recycled hydroponic rockwool slabs. Two experiments were conducted to evaluate the growth of plug seedlings of petunia 'Romeo' in various mixtures including particles of used rockwool slabs (rockwool particles) and wood chips. In the first experiment, seedlings were grown in plugs filled with mixtures of steam- sterilized rockwool particles and chestnut wood chips, which had been weathered for six months and screened through either 2.8 mm or 5.6 mm sieve, at the mixing ratio of 100:0, 75:25, 50:50, 25:75, or 0:100 (v/v). In the second experiment, seedlings were grown in plugs filled with twenty different mixtures of steam-sterilized particles of used hydroponic rockwool slabs with 4 mm chestnut or pine wood chips, coir, peatmoss, or perlite. In the first experiment seedling growth was not affected by particle size of chestnut wood chips, was superior in the control (commercial plug medium) and in 100% rockwool particles, but was suppressed as mixing ratio of chestnut wood chips increased. In the second experiment, leaf length, and shoot fresh and dry weights were the greatest in rockwool particles+peatmoss+coir treatment, followed by rockwool particles+peatmoss treatment. Leaf length was suppressed as ratio of wood chips increased, especially of chestnut wood chips. Root development was the greatest in rockwool particles+peatmoss+perlite treatment, followed by the control, and rockwool particles+peatmoss+coir treatment. The growth was suppressed as the mixing ratio of rockwool particles, peatmoss, or coir decreased.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.5
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• pp.654-658
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• 1999

To investigate an efficient microalgal feed for lariat culture of the Pacific oyster Crassostrea gigas, we prepared three types of Isochrysis aff, galbana (T-iso) : 1) freshly Harvested feed, 2) concentrated feed and 3) freeze-dried feed. The chemical compositions and fatty acid content of these feeds were evaluated and survival rate and lipid content of oyster larvae fed by these feeds were also determined. There was no significant difference in all types of feed in the gross biochemical compositions, In the fatty acid composition, the freeze-dried feed showed a significant increase in the level of polyunsaturated fatty acid (PUFA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) than freshly Harvested feed, especially EPA was 7.35-fold higher than freshly Harvested feed. The survival rate of the oyster larvae was the highest when the larvae were fed with a diet of $10\%$ freeze-dried and $90\%$ concentrated feed; it was 2.1-fold higher than that fed with freshly Harvested food alone. Thereafter, the survival rate decreased with the increased substitutions of freeze-dried food, finally equalling that fed $100\%$ freshly harvested feed at the $30\%$ substitution. Larval lipid content of the oyster was also the highest when the larvae were fed with a diet of $10\%$ freeze-dried and $90\%$ concentrated feed. This increase was by 1.6-fold ver that fed $100\%$ freshly Harvested cells. Thus feed produced during slack times, on a seedling aquaculture farm, and preparedas a freeze-dried diet can be used, mixed with concentrated feed, to supply diets more efficiently and to improve the larvae survival rate of Pacific oyster.

• Horticultural Science & Technology
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• v.30 no.4
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• pp.442-448
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• 2012

Many outbreaks of food-borne illnesses have been associated with the consumption of fresh vegetables and fruits contaminated with food-borne pathogens. Contaminated medium, manure and irrigation water are probable vehicles for the pathogen in many outbreaks. The aim of this study was to determine the potential transfer of Escherichia coli and Bacillus cereus from medium and soil fertilized with contaminated compost or irrigation with contaminated water to the edible parts of lettuce. Moreover, survivals of the two pathogens on lettuce contaminated medium, soil and irrigation water were estimated. Lettuce seeds were planted in medium contaminated with 7.5 log colony forming unit (CFU)/g of E. coli and B. cereus. Seedlings grown in the contaminated medium were transplanted in soil fertilized with contaminated pig manure compost or uncontaminated soil. Contaminated irrigation water with E. coli and B. cereus at 8.0 log CFU/mL was applied only once on the plant by sprinkle irrigation and surface irrigation. Although E. coli and B. cereus in medium and sprouted lettuce after planting seeds were reduced as time passed, these pathogens survived in seedling raising stage for extended periods. The numbers of E. coli and B. cereus in lettuce grown on contaminated soil were detected over 4.0 log CFU/g for 21 days. The numbers of E. coli and B. cereus in lettuce applied by sprinkle irrigation were higher than those of surface irrigation by 5.0 log CFU/g. Our results indicated that contaminated medium, soil and irrigation water can play an important role in the presence of food-borne pathogens on vegetables.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.60 no.2
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• pp.190-196
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• 2015

We evaluated the morphological characteristics in 100 super sweet corn inbred lines, which were developed to breeding super sweet corn variety at Gyeongsangbuk-do Agricultural Research and Extension Services, by examining six quantitative and two qualitative characteristics. On the result of evaluation of two qualitative traits, most of inbred lines showed yellow (91 inbred lines) at seed color (QL1) and weak (68 inbred lines) at seedling vigor (QL2). In the survey of six quantitative traits, the average value for each trait indicated as follows: days of tasseling (QN1, 41.0 to 55.0 days), days of silking (QN2, 44.0 to 59.0 days), anthesis-silking interval (QN3, 2.0 to 7.0 days), tillering (QN4, 0.0 to 2.0), plant height (QN5, 96.0 to 187.0 cm) and ear height (QN6, 30.0 to 86.0 cm). In PCAs (principal component analysis) for 8 morphological characteristics, seedling vigor (QL2) and tillering (QN4) greatly contributed in negative direction and the days of tasseling (QN1) and days of silking (QN2) greatly contributed in positive direction on the first principal component. While, ear height (QN6) and plant height (QN5) contributed in positive direction on the second principal component. Thus these morphological traits, which were greatly contributed in the first and second principal components, might be considered to be useful for discrimination in 100 super sweet corn inbred lines. In our study, the results of morphological variation and PCAs for 100 super sweet corn inbred lines will be helpful for super sweet corn breeding programs such activities as planning crosses for hybrid and line development.

• Journal of Aquaculture
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• v.8 no.2
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• pp.117-131
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• 1995

In order to improve the present running seawater system for seedling production of marine fishes, rearing experiments with the juveniles of black seabream (Acanthopagrus schlegeli) and oblong rockfish (Sebastes oblongus) were conducted. The recirculating seawater system (F) equipped with the rotating biological contactors and the running seawater system (R) were used. Environmental factors, growth, survival rate and rearing density of the fish were compared between two systems during the experimental period. In the rearing experiment of black seabream, water temperature in F was fluctuated with surrounding air temperature and was higher than that in R. Specific gravity of the rearing seawater in F was relatively stable in the range of 1.0252 to 1.0266, while that in R was greatly fluctuated. pH in F turned out to be 7.51, but pH in R was similar to that in the natural seawater. Dissolved nitrite and nitrate in F were higher than those in R. While no significant differences in the growth of black seabream juveniles were recognized between two systems, survival rates of fishes in F were higher than those of fishes in R. In the rearing experiment of oblong rockfish, water temperature in F was higher than that in R. Specific gravity in F was slightly higher than that in R which showed relatively less fluctuation in the range of 1.0253 to 1.0270. pH in F turned out to be 7.96, but pH in R was similar to that in the natural seawater. Dissolved nitrite and nitrate in F were higher than those in R, but ammonia was lower in F. The juveniles of oblong rockfish reared in F grew significantly faster in their total length and body weight than those in R (P<0.05). However, survival rates of fishes between two systems showed no significant differences.

• Journal of the Korean Geographical Society
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• v.29 no.3
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• pp.233-252
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• 1994

One of major advantages of Lumped model is its ability to simulate extended flows. A further advantage is that it requires only conventional, readily available hydrological data (rainfall, evaporation and runoff). These two advantages commend the use of this type of model for the analysis of the hydrological effects of landuse change. Experimental Catchment(K11) of Kimakia site in Kenga experienced three phases of landuse change for sixteen and half years. The Institute of Hydrology offered the hydrological data from the catchment for this research. On basis of Blackie's(l972) 9-parameter model, a new model(R1131) was reorganized in consideration of the following aspects to reflect the hydrological characteristics of the catchment: 1) The evapotranspiration necessary for the landuse hydrology, 2) high permeable soils, 3) small catchment, 4) input option for initial soil moisture deficit, and 5) othel modules for water budget analysis. The new model is constructed as a 11-parameter, 3-storage, 1-input option model. Using a number of initial conditions, the model was optimized to the data of three landuse phases. The model efficiencies were 96.78%, 97.20%, 94.62% and the errors of total flow were -1.78%, -3.36%, -5.32%. The bias of the optimized models were tested by several techniques, The extended flows were simulated in the prediction mode using the optimized model and the data set of the whole series of experimental periods. They are used to analyse the change of daily high and low-flow caused by landuse change. The relative water use ratio of the clearing and seedling phase was 60.21%, but that of the next two phases were 81.23% and 83.78% respectively. The annual peak flows of second and third phase at a 1.5-year return period were decreased by 31.3% and 31.2% compared to that of the first phase. The annual peak flow at a 50-year return period in the second phase was an increase of only 4.8%, and that in the third phase was an increase of 12.9%. The annual minimum flow at a 1.5-year return period was decreased by 34.2% in the second phase, and 34.3% in the third phase. The changes in the annual minimum flows were decreased for the larger return periods; a 20.2% decrease in the second phase and 20.9% decrease in the third phase at a 50-year return period. From the results above, two aspects could be concluded. Firstly, the flow regime in Catchment K11 was changed due to the landuse conversion from the clearing and seedling phade to the intermediate stage of pine plantation. But, The flow regime was little affected after the pine trees reached a certain height. Secondly, the effects of the pine plantation on the daily high- and low-flow were reduced with the increase in flood size and the severity of drought.

• Journal of Korean Society of Forest Science
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• v.87 no.3
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• pp.493-500
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• 1998

To investigate the effects of light intensity on the growth, and the critical minimum light intensity for growing of Cornus controversa seedlings at the stage of cotyledon, hypocotyl elongation, cotyledon expansion, the times of leaves appearance, dry weights of each organ, and specific leaf area(SLA) were measured on a growth chamber with several light intensity gradients(385, 32, 17, 8, and $5{\mu}mol\;m^{-2}s^{-1}$). There was a positive correlationship between the size of cotyledon and the biomass of cotyledon and total seedling. Hypocotyl was more elongated under relatively low light intensities, such as 32, 17, 8, and $5{\mu}mol\;m^{-2}s^{-1}$ than under $385{\mu}mol\;m^{-2}s^{-1}$ light intensity, however, dry weight of the hypocotyl was adverse. As the light intensities decreased, the leaf appearance was delayed and the number of leaves decresed. In addition, leaves did not appear under $8{\mu}mol\;m^{-2}s^{-1}$ and $5{\mu}mol\;m^{-2}s^{-1}$ light intensity. Although cotyledons were more fully expanded under 32 and $17{\mu}mol\;m^{-2}s^{-1}$ light intensities than $385{\mu}mol\;m^{-2}s^{-1}$ light intensity, the dry weights of cotyledons were greater under the high light intensity. The dry weight of cotyledon, hypocotyl, root and leaves showed a decreased pattern with decreasing light intensities, but root to shoot(hypocotyl+leaves) ratio rapidly increased. Roots did not develop below $8{\mu}mol\;m^{-2}s^{-1}$ light intensity. In conclusion, the results showed that the critical minimum light intensity for growing of Cornus controversa seedlings was above $17{\mu}mol\;m^{-2}s^{-1}$ light intensity.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.s02
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• pp.34-44
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• 1989

The stability of rice cultivation in Korea is largely depended on climatic conditions, especially, low temperature at the period of early growth stage and after heading. The improvement of cold tolerant varieties and appropriate cultural practices in rice are very effective to minimize the cold damage. This paper is summarized the mechanism and counterplans of cold injury of rice plants. The paddy area having commonly cold injury in Korea is approximately 15, 522ha in 1,709 sites on the national scale. The cold damage at seedling stage in nursery bed appeared to poor germination, leaf discoloration, dead seedlings and seedling rot ect.. At the vegetative stage, the decreased tiller number due to poor rooting and the delayed heading caused by slow growth and panicle differentiation are commonly showed. The cold injury at early reproductive stage appeared to the degeneration of spikelets and rachis - branches, while that at meiosis stage showed to increased sterility due to poor development of pollen and shortened panicle length with delaying heading, therefore the grain yield is largely decreased. The cold damage at heading and ripening stages showed to poor pollination and fertilization, low panicle exsertion, poor grain filling and finally grain quality became low. To minimize the cold injury to rice plants by low temperature, following counterplans would be recommonded ; Improvement of the cold toelrant rice varieties for the regions of midmountains and alpines. Raising healthy seedlings at upland nursery beds and by using of growth regulators such as ABA, Fuchiwang and Tachiace. Soil improvement and organic matter application to reduce cold damage by increasing water and fertilizer holding capacities in the paddy field having commonly cold water and in the place where cold damage is regularly occurred. Appropriate fertilization for raising healthy rice plants to tolerate under low temperature condition. Water management to increase water temperature in the paddy such as depth watering, round channels and polyethylene tubes around the field. Establishment of the optimum cultivation time of rice based on minimum, mean and maximum temperatures at different regions with appropriate rice varieties.