• Research in Plant Disease
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• v.17 no.2
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• pp.161-168
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• 2011

To establish simple and reliable screening method for resistant radish to Plasmodiophora brassicae Woron. using soil-drenching inoculation, the development of clubroot on radish seedlings inoculated with P. brassicae GN-1 isolate according to several conditions such as inoculum concentration, plant growth stage and incubation period after inoculation was studied. To select resistant radish against clubroot, 10-day-old seedlings were inoculated with P. brassicae by drenching the roots with the spore suspension of the pathogen to give $1{\times}10^9$ spores/pot. The inoculated seedlings were incubated in a growth chamber at $20^{\circ}C$ for 3 days then cultivated in a greenhouse ($20{\pm}5^{\circ}C$) for 6 weeks. Under the optimum conditions, 46 commercial cultivars of radish were tested for resistance to YC-1 (infecting 15 clubroot-resistant cultivars of Chinese cabbage) and GN-1 (wild type) isolates of P. brassicae. Among them, thirty-five cultivars showed resistance to both isolates and one cultivar represented susceptible response to the pathogens. On the other hand, the other cultivars showed different responses against the tested P. brassicae pathogens. The results suggest that this method is an efficient system for screening radish with resistance to clubroot.

• Research in Plant Disease
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• v.17 no.2
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• pp.121-128
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• 2011

Bacteriolytic myxobacteria have been known to secrete various antifungal metabolites against several soilborne phytopathogens including Phytophthora. Among the three isolates of Myxococcus spp., KYC 1126 and KYC 1136 perfectly inhibited the mycelial growth of Phytophtora capsici in vitro. In order to show the biocontrol activity on Phytophthora blight of hot pepper, we tried to find the best way of application of a myxobacterial isolate. Although KYC 1126 fruiting body was easily grown on the colony of Escherichia coli as a nutrient source, it did not control the disease when it was pre-applied in soil. Before the bioassay of a liquid culture filtrate of KYC 1126 was conducted, its antifungal activity was confirmed on the seedlings applying with the mixture of the pathogen's zoospore suspension and KYC 1126 filtrate. On greenhouse experiments with five and four replications, the control value of KYC 1126 on phyllosphere and rhizosphere was 88% and 36%, respectively. Whereas, the control value of dimetnomorph+propineb on phyllosphere was 100% and that of propamorcarb on rhizosphere was 44%. There was a phytotoxicity of the myxobacterial filtrate when seedlings were washed and soaked for 24 hours. Gummy materials were covered with roots. And stem and petiole were constricted, then a whole seedling was eventually blighted.

• Korean journal of applied entomology
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• v.45 no.3 s.144
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• pp.275-282
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• 2006

Insect pests attacking the leaf of lettuce (Lactuca sativa) were surveyed in environmentally frendly leaf-lettuce-greenhouses in Hwaseong, Namyangju, and Suwon from 2003 to 2004. Sixteen insect species of eleven families in eight orders were collected in greenhouses. Among them, Acyrthosiphon solani, Frankliniella occidentalis, and Autographa nigrisigna were the most serious pest species because of their damage ratio was over 30%. Population of Acyrthosiphon solani showed the highest peak one or two times between mid-April and early June in both the second and the third cropping period. Frankliniella occidentalis reached the highest peak one or two times, the first peak between mid-June and the late July, and the second peak between the mid-August and the mid-October.Autographa nigrisigna reached the highest peak one or times between early June and late July and in the mid-August to late October. The highest peak occurrence of A. solami was observed in early June as many as 4,836 nymphs and adults per 100 leaves. And for F. occidentalis it was in early July occurring 437 larvae and adults per 100 leaves, for A. nigrisigna in early October occurring 42 larvae per 100 leaves. The density of F. occidentalis and its damage as well was greater in soil culture than in hydroponic culture, but in case of both A. solani and A. nigrisigna no such difference between cropping systems was found.

• Korean Journal of Ecology and Environment
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• v.34 no.4 s.96
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• pp.261-266
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• 2001

Effects of elevated carbon dioxide ($CO_2$) on soil microbial processes were studied in a northern peatland. Intact peat cores with surface vegetation were collected from a northern Welsh fen, and incubated either under elevated carbon dioxide (700 ppm) or ambient carbon dioxide (350 ppm) conditions for 4 months. Higher algal biomass was found under the elevated $CO_2$ condition, suggesting $CO_2$ fertilization effect on primary production, At the end of the incubation, trace gas production and consumption were analyzed using chemical inhibitors. For methane ($CH_4$ ), methyl fluoride ($CH_3F$) was applied to determine methane oxidation rates, while acetylene ($C_2H_2$) blocking method were applied to determine nitrification and denitrification rates. First, we have adopted those methods to optimize the reaction conditions for the wetland samples. Secondly, the methods were applied to the samples incubated under two levels of $CO_2$. The results exhibited that elevated carbon dioxide increased both methane production (210 vs. $100\;ng\;CH_4 g^{-1}\;hr^{-1}$) and oxidation (128 vs. $15\;ng\;CH_4 g^{-1}\;hr^{-1}$), resulting in no net increase in methane flux. For nitrous oxide ($N_2O$) , elevated carbon dioxide enhanced nitrous oxide emission probably from activation of nitrification process rather than denitrification rates. All of these changes seemed to be substantially influenced by higher oxygen diffusion from enhanced algal productivity under elevated $CO_2$.

• Korean Journal of Environmental Agriculture
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• v.26 no.1
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• pp.25-35
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• 2007

Excess runoff contaminated with N and P can impact the quality of downstream water. It has been known that aquatic plants improve the water quality through their intake of organic or inorganic nutrients. This study was conducted to select aquatic plants having high purification ability for nutrient N and P, and mineral nutrients related to EC such as K, Ca, Na, Cl, and $SO_4$ in raw sewage water in greenhouse. We assessed nutrient phytoremediation potential of alien hydrophyte and hydro-crop as well as native landscape hydrophyte to select suitable aquatic plant applied to artificial wetland and buffering site of stream-side. The amount of irrigation water during whole growing period of aquatic plane ranged from 225 L $m^{-2}$ to 444 L $m^{-2}$. Oryza sativa, Typha orientalis, Zizania latifolia, Aster subulatus, Coix lachryma-jobi var. mayuen, Paspalum disdichum var. indutum which had high biomass consumed the large amount of irrigation water over 350 L $m^{-2}$. As a result of analysis of water purification effect N and P content of shoot biomass, and media soil after experiment, Oryza sativa, Zizania latifolia, Aster subulatus, Coix lachryma-jobi var. mayuen, Paspalum distichum var. indutum showed high purification ability about eutrophication elements such as T-N and T-P. It is presented that Pistia stratiotes, Eichhornia crassipes, and Paspalum distichum var. indutum had excellent purification ability about K, Ca, Na, and Cl. Moreover, Paspalum distichum var. indutum greatly removed $SO_4$ in row sewage water.

• Research in Plant Disease
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• v.12 no.3
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• pp.158-163
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• 2006

Sclerotinia rot caused by Sclerotinia sclerotiorum frequently causes serious and unpredicable yield losses of the leaves of perilla growing under structured cultivation as vegetable in Korea. Temperature for mycelial growth ranged from 5 to $30^{\circ}C$ with optimum temperature d $20^{\circ}C$. Sclerotia were formed fewer at low temperature, but their dry weight was heavier than that at high temperature. The apothecia were formed from the sclerotia that buried up to 3 cm soil depth at $15^{\circ}C$ in moisture condition. The incidence of perilla Sclerotinia rot caused by S. sclerotiorum was observed throughout the growing season at greenhouse. The occurrence of this disease was especially severe from January to February of low temperature period. The average incidence rates of this disease was up to 15%. The significant occurrence of this disease was showed mainly in the continuous cropping field for more than five years. The incidence of this disease increased according to the increase of continuous cropping year. The incidence rates of this disease reached up to 20% in the continuous cropping field for ten years. Also it was firstly investigated the natural infection caused by S. sclerotiorum on weed plants, Gnaphalium affine and Mazus pumilus in farmer's field. The casual fungus showed pathogenicity on 11 weed plants species tested, and more severe pathogenicity on G. affine, Latuca indica and Ixeris dentata included in the family Compositae. This result suggests that effective crop rotation and weed eradication can be the method for organic control of perilla sclerotinia rot, and sudden outbreaks of this disease on perilla growing under structure after paddy rice call be explained by the presence of weed hosts.

• Research in Plant Disease
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• v.15 no.1
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• pp.1-7
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• 2009

Viruses diagnosed on crops including rice plants from farmers or agricultural extension agencies cover the country were 11 species including Broad bean wilt virus 2 (BBWV2) in 2008. Tomato spotted wilt virus (TSWV) was the most important virus having the detection rate of 22.9%. Two viruses of Tomato yellow leaf curl virus (TYLCV) and Tobacco leaf curl virus (TLCV) inducing leaf yellow and curl diseases on tomatoes were occurred newly with the detection rate of 12.2% and 4.0%, respectively, in 2008. Rice stripe virus (RSV) was occurred on 869.5 ha mainly at Jindo and Haenam areas in Jeollanamdo province. At Jindo area, 12 plots were damaged severely with the infected hill rate of 83.8%. At the main production area of oriental melon at Seongju, almost all fruits from whole sale market at Seongju were infected with Cucumber green mottle mosaic virus (CGMMV) as the detection rate of 87%. The areas occurred TSWV in Korea were 25 totally from 2003 including 7 areas newly reported in 2008 including Naju in Jeoallanamdo. TSWV could be reduced as 0.1 % from 5.3% by covering insect proof net in vinyl house after chemical soil sterilization. Tomato yellow leaf curl disease was occurred on April in 2008 at Tongyoung area in Kyeongsangnamdo, and detected continuously at 13 areas, 7 in Kyeongsangnamdo, 4 in Jeollabukdo and 2 in Jejudo. Potato spindle tuber viroid (PSTVd) was occurred abruptly in a confined space of a civil breeding greenhouse and a cultivar evaluation field followed by disuse 17.4 M/T of potato tubers. No PSTVd was detected at 17 fields cultivated the related potatoes to the bred company by RT-PCR.

• Korean Journal of Plant Tissue Culture
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• v.22 no.3
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• pp.121-126
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• 1995

Diploid plants were obtained by anther culture of tetraploid poplar(Populus alba L. X P.glandutosa Uyeki). The effect 2,4D on callus formation from anther culture was greater than any other auxins tested. The highest average number of multiple shoots per callus was obtained when zeatin was used at levels of 6-8 ${\mu}$M. Regenerated shoots were excised and transferred to MS basal medium. Rooted plantlets were subsequently transferred to pots containing artificial soil mix. Finally 100 plane were transplanted in nursery located in forest Genetics Research Institute. for the 300 anther clones growing in greenhouse for 6 months after transplanting, 33% were slow-growing, 47% were rapid-growing and 20% had huge leaf size with rapid-growing characteristics. Chromosome study showed a narrow range of variation from diploid to tetraploid. DNA polymorphism studies using various RAPD markers revealed some extend of differences among the anther-clones in their band pattern.

• The Korean Journal of Mycology
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• v.24 no.4 s.79
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• pp.293-304
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• 1996

A bacterial strain, KSl, possessing strong antifungal activity was isolated from soil samples of ginseng fields and identified as Bacillus subtilis. In greenhouse test, the culture filtrate of B. subtilis KS1 showed strong protective effect against several fungal diseases of agricultural plants such as cucumber gray mold and wheat leaf rust. In addition, the crude butanol fraction of the culture filtrate exhibited antagonistic effect against several fungi including plant or human pathogens, such as Botrytis maydis, Chytridium lagenarium and Candida albicans. The antifungal compound, SW1, produced by B. subtilis KS1 was purified through consecutive chromatographic separations on a pep-RPC column and a ${\mu}$ Bondapak $C_{18}$ reverse phase column. Temperature and pH showed little effect on the stability of the compound in the ranges $-20-121^{\circ}C$ and pH 4.0-10.0, respectively. The composition and structural characteristics of SW1 were analysed by HPLC and by $^1H-,\;^1H-^1H-COSY$, NOESY, COSY-NOESY and HOHAHA NMR spectroscopy, respectively, which revealed that the compound belongs to iturin A, a typical cyclic antifungal compound produced by B. subtilis. In contrast to the previously reported iturin A compounds which have one or no $-CH_3$ side chain in the hydrophobic hydrocarbon chain of ${\beta}-amino$ acids, SW1 was shown to have a ${\beta}-amino$ acid containing 12-carbon skeleton with two $-CH_3$ side chains.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.61 no.4
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• pp.251-256
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• 2016

The increase in carbon stock and sustainability of crop production are the main challenges in agricultural fields relevant to climate change. Methane is the most important greenhouse gas emitted from paddy fields. This study was conducted to investigate the effects of tillage and cultivation methods on methane emissions in rice production in 2014 and 2015. Different combinations of tillage and cultivation were implemented, including conventional tillage-transplanting (T-T), tillage-wet hill seeding (T-W), minimum tillage-dry seeding (MT-D), and no-tillage-dry seeding (NT-D). The amount of methane emitted was the highest in T-T treatment. In MT-D and NT-D treatments, methane emissions were significantly decreased by 77%, compared with that in T-T treatment. Conversely, the soil total carbon (STC) content was higher in MT-D and NT-D plots than in tillage plots. In both years, methane emissions were highly correlated with the dry weight of rice ($R^2=0.62{\sim}0.96$), although the cumulative emissions during the rice growing period was higher in 2014 than in 2015. T-T treatment showed the highest $R^2$ (0.93) among the four treatments. Rice grain yields did not significantly differ with the tillage and cultivation methods used. These results suggest that NT-D practice in rice production could reduce the methane emissions and increase the STC content without loss in grain yield.