• The Plant Pathology Journal
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• v.35 no.6
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• pp.662-673
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• 2019

Root-knot nematodes (RKNs) are among the most destructive plant-parasites worldwide, and RKN control has been attempted mainly using chemical nematicides. However, these chemical nematicides have negative effects on humans and the environment, thus necessitating the search for eco-friendly alternative RKN control methods. Here, we screened nematicidal lactic acid bacteria (LAB) isolated from kimchi and evaluated their efficacy as biocontrol agents against RKNs. Of 237 bacterial strains, Lactobacillus brevis WiKim0069 showed the strongest nematicidal activity against the second-stage juveniles (J2) of Meloidogyne incognita, M. arenaria, and M. hapla and inhibited the egg hatch of M. incognita. The culture filtrate of WiKim0069 had a pH of 4.2 and contained acetic acid (11,190 ㎍/ml), lactic acid (7,790 ㎍/ml), malic acid (470 ㎍/ml), and succinic acid (660 ㎍/ml). An artificial mixture of the four organic acids produced by WiKim0069 also induced 98% M. incognita J2 mortality at a concentration of 1.25%, indicating that its nematicidal activity was derived mainly from the four organic acids. Application of WiKim0069 culture filtrate suppressed the formation of galls and egg masses on tomato roots by M. incognita in a dose-dependent manner in a pot experiment. The fermentation broth of WiKim0069 also reduced gall formation on melon under field conditions, with a higher efficacy (62.8%) than that of fosthiazate (32.8%). This study is the first report to identify the effectiveness of kimchi LAB against RKNs and to demonstrate that the organic acids produced by LAB can be used for the RKN management.

• Korean journal of applied entomology
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• v.45 no.3 s.144
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• pp.327-331
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• 2006

This study was carried out to determine the economic injury level of the rice leaffolder,Cnaphalocrocis medinalis G.. The damage aspects of rice plant (at tilling stage) by leaf folders at different larval density per plant were studied in pot experiment (24 cm in diameter, 18 cm in height). One leaf folder consumed 6-7 leaves during larval stage. The damage by leaf folders was simulated by cutting off 0, 10, 30, 50, 70, and 90% of leaves before and after heading stage July 15th (at panicle initiation stage) and August 15th (at milk stage), respectively. When leaves were cut before the heading of rice, the linear relationships between the leaf cutting rate (X) and each factors of yield (Y) were as following; for grain maturity it was Y = -9.379X + 83.630 ($R^{2}=0.493$),\;Y = 0.139X + 0.490 ($R^{2}=0.925$) for yield, and Y = -4.880X + 81.116 ($R^{2}=0.665$) for head rice. When leaves were cut after the heading of rice, it was Y = -23.0l4X + 83.589 ($R{2}=0.915$), for grain maturity, Y=0.141X + 3.466 ($R^{2}=0.842$) for yield, and Y = -13.795X + 81.964 ($R^{2}=0.898$) for head rice. We found that when leaf cutting after the heading stage caused more damage than before the heading in terms of yield and yield components. Based on theses results the economic threshold level was estimated to be 30% and 7% leaf loss before and after heading stage.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.201-201
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• 2017

Delayed stem senescence of soybean is a phenomenon of retarded leaf and stem yellowing, where plants maintain a high stem water content and remain chlorophyll in leaf and stem at maturity stage. This phenomenon was one of the most important physiological disease in Japanese soybean cultivation. The occurrence of delayed stem senescence was affected by sowing time. And the most of Japanese field, soybean seeds were sowed in June. June is the rainy season in Japan, and the soil water content of field become higher in this season. In this study, the effects of late sowing (July sowing) on the yield and the occurrence of delayed stem senescence in soybean cultivars Enrei, Tachinagaha and Ayakogane were examined from 2013 to 2015, in the experimental farm at Nihon University (Fujisawa-city, Kanagawa, Japan). The seeds of all cultivars were sowed in June (June-normal density plot) or July (July-normal density plot, July-high density plot and July-super high density plot) in field experiment. The pot experiments were carried out in 2014. In all cultivars, the yield of July-high density plot and July-super high density were higher than that of June normal density plot. And the yield of June-normal density plot was the same as that of July-normal density plot. In all cultivars, the occurrence of delayed stem senescence was increased by seeding in June sowing. And in July sowing plots, no significance difference in the occurrence of delayed stem senescence was observed among density plots. One of reason about the increasing the occurrence of delayed stem senescence in June-normal plot was the increasing of the damaged seeds by bean bugs. Add one of reason about the decreasing of the occurrence of delayed stem senescence of July plots was the decreasing of the amount of cytokinin supplied from root to top and water stress after the flowering time was improved compared with the June plot. In conclusion, the yield of Enrei, Tachinagaha and Ayakogane were not changed by changing the sowing time from June to July. In all cultivars, the occurrence of delayed stem senescence were decreasing by seeding in July.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.308-308
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• 2017

The low and unstable yield of soybean has been a major problem in Japan. Excess soil moisture conditions are one of the major factors to restrict soybean productivity. More than 80 % of soybean crops are cultivated in converted paddy fields which often have poor drainage. In central and eastern regions of Japan, the early vegetative growth of soybean tends to be restricted by the flooding damage because the early growth period is overlapped with the rainy season. Field observation shows that induced excess water stress in early vegetative stage reduces dry matter production by decreasing intercepted radiation by leaf and radiation use efficiency (RUE) (Bajgain et al., 2015). Therefore, it is necessary to evaluate the responses of soybean growth for excess water conditions to assess these effects on soybean productions. In this study, we aim to modify the soybean crop model (Sinclair et al., 2003) by adding the components of the restriction of leaf area development and RUE for adaptable to excess water conditions. This model was consist of five components, phenological model, leaf area development model, dry matter production model, plant nitrogen model and soil water balance model. The model structures and parameters were estimated from the data obtained from the field experiment in Tsukuba. The excess water effects on the leaf area development were modeled with consideration of decrease of blanch emergence and individual leaf expansion as a function of temperature and ground water level from pot experiments. The nitrogen fixation and nitrogen absorption from soil were assumed to be inhibited by excess water stress and the RUE was assumed to be decreasing according to the decline of leaf nitrogen concentration. The results of the modified model were better agreement with the field observations of the induced excess water stress in paddy field. By coupling the crop model and the ground water level model, it may be possible to assess the impact of excess water conditions for soybean production quantitatively.

• Research in Plant Disease
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• v.12 no.3
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• pp.260-266
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• 2006

Pythium blight caused by Pythium spp. is one of major diseases in putting green of golf course. In this study, microorganisms which are anatgonistic to Pythium aphanidermatum, a pathogen of pythium blight, were selected primary through in vitro tests, dual culture method and triple layer agar diffusion method. In vivo test against pythium blight were conducted to select the best candidate biocontrol microorganism by pot experiment in a plastic house. Bacillus subtilis GB-0365 was finally selected as a biocontrol agent against pythium blight. Relative Performance Indies(RPI) was used as a criterion of selecting potential biocontrol agent. B. subtilis GB-0365 showed resistance to major synthetic agrochemicals used in golf course. Alternative application of synthetic agrochemicals and B. subtilis GB-0365 was most effective to successfully contol pythium blight. B. subtilis GB-0365 suppressed the development of pythium bight of bentgrass by 56.4% as compared to non-treated control and its disease control efficacy was 60.9% of a synthetic fungicide Oxapro(WP) efficacy. B. subtilis GB-0365 has a potential to be a biocontrol agent for control of pythium blight.

• Korean Journal of Soil Science and Fertilizer
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• v.14 no.1
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• pp.44-50
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• 1981

A pot experiment was conducted to find the nitrogen fixing activities associated with ice rhizoplane in nine varieties at various growth stage by acetylene reduction technique. Results obtained ware Summarized as follows. 1. Nitrog en fixing activites associated with rice rhizoplane differ by the rice variety and the growth stage. The activities increased with progressing of growing time, and maximum activities were obtained from the ear forming stage to the heading stage. 2. The application of rice straw did not greatly enhanced the nitrogen fixing activities associated with rice rhizoplane. However, somewhat increasing tendency was obtained in the Kataktara, TKM-6, Centrypartna. Daegujo, and Jodongji varieties. 3. The nitrogen fixed during the one rice cropping period was estimated as 0.55kg of N per 10a by Milyang-23 variety to 2.6kg of N per 10a by Jodongji variety. 4. The amount of rice root showed no significant relationship with the amount of nitrogen fixed during the growing period of rice plant.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.4
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• pp.333-342
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• 1983

A pot experiment was conducted to find out the effect of application amounts of silicates on the fatty acid and sterol composition of paddy rice at various growing stages. The results obtained were as follows; 1. At maximum tillering stage and heading stage, significant positive correlations were obtained between the ratio of unsaturated fatty acid to saturated fatty acid and silica absorption, dry matter or grain yield, respectively. But significant correlation was not observed between them at harvesting time. 2. At maximum tillering stage and heading stage, the ratio of unsaturated fatty acid to saturated fatty acid in paddy rice was increased with increasing silica application from 80 to 180 ppm of soil, but these ratio was decreased at the plot of 200Kg/10a of silicate. 3. The ratio of sitosterol to stigmasterol in paddy rice at maximum tillering stage was increased with increasing silica application of soil, but these ratio was increased with increasing silica application up to 180 ppm of soil at heading stage, and was decreased at the plot of 200Kg/10a (410 ppm in soil) application of silicates.

• Korean Journal of Soil Science and Fertilizer
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• v.13 no.3
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• pp.85-91
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• 1981

In order to evaluate effectiveness of zinc source on uptake of zinc by rice plant, a pot experiment carried out using ZnEDTA and $ZnSO_4$ in a glasshouse. The results obtained were summarized as follows: The effectiveness of zinc source on uptake of zinc by rice plants was different with different soil. Namely ZnEDTA was more efficient than $ZnSO_4$ in increasing yield of zinc and concentration of zinc in the plant grown on Jecheon calcareous soil. In case of Keumgok acid soil, however, no superiority of ZnEDTA treatment was found. The plant growing status of ZnEDTA treated calcareous soil was also shown that larger number of tillers per hill, bigger height of the plant and good yield of dry matter production than those of the plant grown on $ZnSO_4$ treatment. Regardless of the zinc source, smaller number of tillers per hill, shorter height of the plant, and the lowest yield of dry matter were shown in the treatment of zinc and straw mixed with both soils. It seemed that more applied zinc was to be fixed by the straw application resulting in poor zinc yield. The extent of the zinc fixation showed markedly in Jecheon calcareous soil.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.2
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• pp.161-167
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• 1997

The effect of Bituminous and Anthracite coal ash(fly ash) on the performance of Chinese cabbage on an acid soil was studied through a pot experiment. The levels of application of the materials tested were five, 10 and 15% of dry soil weight. Regardless of the kind of fly ash, the application of it, tended to increase the yield of Chinese cabbage by 13 to 24% in fresh weight. Difference in application levels did not result in the difference in increasing the yield of Chinese cabbage. The application of fly ash tended to lower the all of the mineral nutrient contents in the Chinese cabbage, excepting boron. Boron content tended to increase along with the application of fly ash. Bituminous ash raised the pH of soil and increased available P, exchangeable Ca and soluble boron in the soil remarkably. Anthracite ash, on the other hand, did not increase the contents of other components in the soil, than soluble born.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.1
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• pp.44-51
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• 1992

Results as follows are obtained from the pot experiment to examine effect of application of organic substances on inhibition of occurrence of root rot of red pepper. 1. As for effects of applicating organic materials on inhibition of red pepper root rot, it is more effective to apply in autumn than to apply in summer, when the temperature is high. In addition, organic substance which is not decomposed completely such as rice straw is more effective than matured compost types. As for effects of applicating organic substances on composition of soil microorganisms, increase of fungi and bacteria in view of numbers is remarkable, especially in case of applying rice straw. 2. From the examination of Phytophthora capsici in soil at the 1st cultivation period in autumn, no P. capsici can be isolated in early stage of growth of red pepper in nontreated soil and in soil applied compost. However, as the time goes on, P. capsici are detected. While in early stage of cultivation, P. capsici are detected in soil applied with rice straw, P. capsici are not isolated after middle stage of cultivation. 3. It is recognized that there are many differences according to the types of organic materials applied in the result of identification of fungi in each treatment. And, proportion of antagonistic fungi to total fungi in soil applied rice straw is proved to be significantly higher compared to other treatments.