• Korean Journal of Organic Agriculture
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• v.26 no.4
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• pp.731-743
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• 2018

This study was conducted to evaluate the effects of green manures and complemental fertilization with oil cake or liquid fertilizer on growth and nitrogen use efficiency of Chinese cabbage cultivated in organi systems. Field experiments were carried out at the National Institute of Agricultural Science in Suwon, South Korea from 2012 to 2014. Two green manure crops, Crotalaria and Hairy vetch, was cultivated in summer and in winter, respectively. The application methods of the green manure consisted of three tillage systems (overall tillage, partial tillage and no tillage). Oil cake and liquid fertilizer were used as complemental fertilizer. The results showed that when used as covering material in the upland soil without tillage, green manure fertilization was more effective in increasing growth and yield of Chinese cabbage than when incorporated into soil. It was possible to grow and harvest Chinese cabbage in the spring season by the application of hairy vetch as winter green manure. The higher yield of Chinese cabbage with green manure application was caused by the lower incidence rate of soft rot and tip-burn. The yield of the Chines cabbage that received green manure applications over two consecutive seasons followed by the supplemental fertilization with oil cake was similar to that of the conventional chemical fertilization. Following a single season green manure application in summer, however, the yield of cabbage was only about 70% of the conventional treatment. Green manure cultivation with additional liquid fertilization produced a yield similar to the conventional fertilization treatment, soil inorganic nitrogen concentration remained stable and the nitrogen use efficiency increased in the green manure applied soil. In conclusion, the organic cultivation of Chinese cabbage in the autumn season could be outperformed in the upland soil receiving two seasons (winter and summer) of green manure fertilization followed by the supplemental fertilization with liquid fertilizer.

• Research in Plant Disease
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• v.22 no.4
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• pp.284-288
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• 2016

A plant growth promoting rhizobacterium, Bacillus vallismortis BS07M, was formulated as a clay pellet (CP) to evaluate its pepper growth promotion and induced resistance against various diseases under field and storage conditions. Peppers were grown in 50-hole tray containing potting mixture with CP in seedling raising stage, and then it was transplanted into a field. After transplanting, pepper plants treated with CP in seedling raising stage increased shoot growth and reduced disease severity caused by Phytophthora capsici in detached pepper leaves compared to untreated control. Moreover, treatment with CP in seedling raising stage increased fruit weight per plant; after harvesting, pepper fruits shown reduced diameter of lesions by Colletotrichum acutatum, and occurrance of soft rot in storage condition. These results indicated that CP could affect plant growth and induced resistance in pepper plants under field condition, and maintenance of fruit during storage.

• The Korean Journal of Pesticide Science
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• v.14 no.4
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• pp.407-414
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• 2010

Bacillus subtilis strains isolated from different regions of Korea were screened for their plant growth promotion and induced systemic resistance (ISR) in tomato and red-pepper. The plant growth promotion on red-pepper and tomato revealed maximum plant height (22.73 cm) on red pepper treated with B. subtilis strain JE 21-1 and 30.18cm in case of tomato treated with B. subtilis strain JE 8-1. There was also significant improvement in root and shoot dry weight in both the plants. The strain JE 21-1 showed better promise for all growth parameters in red-pepper and tomato when compared to other strains and positive check BTH. Different strains screened in square plate method also revealed maximum plant height and leaf width, and suppressed anthracnose on red pepper in case of strain JE 21-1 at $10^6$ and $10^7$ cells/ml when compared to other strains. In all the bacterial inoculations the population was significantly high when compared to untreated check. In plant growth promotion with respect to fruit length and weight, fruit length was maximal in treating with JE 9-4 and ES 2-2, while fruit weight was maximal in treating with JE 3-6, ES4-2, ES2-2 and JE 21-2 on red pepper. In case of tomato, comparatively better fruit weight was in JE 21-1, ES 3-3 and JE 10-2 when compared to BTH and untreated control. The soft rot disease caused by Pectobacterium carotovorum SCCI was completely suppressed in case of transgenic tobacco harboring GUS gene related to PR1a and increased the level of salicylic acid significantly in combined application of JE 9-4 on par with BTH. Thus, this study clarified some potential Bacillus subtilis strains for plant growth promotion and ISR in red-pepper and tomato.

• Horticultural Science & Technology
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• v.32 no.3
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• pp.318-329
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• 2014

In order to gain insight into the physiological responses of plants to high temperature stress, the effects of temperature on Chinese cabbage (Brassica campestris subsp. napus var. pekinensis cv. Detong) were investigated through analyses of photosynthesis and chlorophyll fluorescence under 3 different temperatures in the temperature gradient tunnel. Growth (leaf length and number of leaves) during the rosette stage was greater at ambient $+4^{\circ}C$ and ambient $+7^{\circ}C$ temperatures than at ambient temperature. Photosynthetic $CO_2$ fixation rates of Chinese cabbage grown under the different temperatures did not differ significantly. However, dark respiration rate was significantly higher in the cabbage that developed under ambient temperature relative to elevated temperature. Furthermore, elevated growth temperature increased transpiration rate and stomatal conductance resulting in an overall decrease of water use efficiency. The chlorophyll a fluorescence transient was also considerably affected by high temperature stress; the fluorescence yield $F_J$, $F_I$, and $F_P$ decreased considerably at ambient $+4^{\circ}C$ and ambient $+7^{\circ}C$ temperatures, with induction of $F_K$ and decrease of $F_V/F_O$. The values of RC/CS, ABS/CS, TRo/CS, and ETo/CS decreased considerably, while DIo/CS increased with increased growth temperature. The symptoms of soft-rot disease were observed in the inner part of the cabbage heads after 7, 9, and/or 10 weeks of cultivation at ambient $+4^{\circ}C$ and ambient $+7^{\circ}C$ temperatures, but not in the cabbage heads growing at ambient temperature. These results show that Chinese cabbage could be negatively affected by high temperature under a future climate change scenario. Therefore, to maintain the high productivity and quality of Chinese cabbage, it may be necessary to develop new high temperature tolerant cultivars or to markedly improve cropping systems. In addition, it would be possible to use the non-invasive fluorescence parameters $F_O$, $F_V/F_M$, and $F_V/F_O$, as well as $F_K$, $M_O$, $S_M$, RC/CS, ETo/CS, $PI_{abs}$, and $SFI_{abs}$ (which were selected in this study), to quantitatively determine the physiological status of plants in response to high temperature stresses.

• Journal of Food Hygiene and Safety
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• v.34 no.3
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• pp.227-234
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• 2019

An analytical method was developed for the determination of oxytetracycline in agricultural products using the QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method by liquid chromatography-tandem mass spectrometry (LC-MS/MS). After the samples were extracted with methanol, the extracts were adjusted to pH 4 by formic acid and sodium chloride was added to remove water. Dispersive solid phase extraction (d-SPE) cleanup was carried out using $MgSO_4$ (anhydrous magnesium sulfate), PSA (primary secondary amine), $C_{18}$ (octadecyl) and GCB (graphitized carbon black). The analytes were quantified and confirmed with LC-MS/MS using ESI (electrospray ionization) in positive ion MRM (multiple reaction monitoring) mode. The matrix-matched calibration curves were constructed using six levels ($0.001{\sim}0.25{\mu}g/mL$) and coefficient of determination ($r^2$) was above 0.99. Recovery results at three concentrations (LOQ, $10{\times}LOQ$, and $50{\times}LOQ$, n=5) were from 80.0 to 108.2% with relative standard deviations (RSDs) less than of 11.4%. For inter-laboratory validation, the average recovery was in the range of 83.5~103.2% and the coefficient of variation (CV) was below 14.1%. All results satisfied the criteria ranges requested in the Codex guidelines (CAC/GL 40-1993, 2003) and the Food Safety Evaluation Department guidelines (2016). The proposed analytical method was accurate, effective and sensitive for oxytetracycline determination in agricultural commodities. This study could be useful for safety management of oxytetracycline residues in agricultural products.

• Journal of Ginseng Research
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• v.32 no.4
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• pp.275-278
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• 2008

Ginseng stem fungus gnat, Phytosciara procera, is reported as a ginseng pest for the first time. It is new to science that a member of the family Sciaridae is a ginseng pest. In our observation, larvae of the gnat can penetrate the stem of ginseng, and then they make a shaft in shoot and root. Number of adults captured by yellow sticky traps were peaked in twice, from late July to early August and from late August to early September. In a ginseng field, 29.7% of ginseng damaged by Phytosciara procera is also infected by bacterial disease caused by Erwinia carotobora. However, there is a possibility on environmental-friendly control, as a result of decreasing effect of damage over 85% when remaining a part of berry on peduncle than tatally remove.

• Research in Plant Disease
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• v.11 no.2
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• pp.140-145
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• 2005

A collection of 12 Erwinia carotovora strains from blackleg diseased potato in Jeju island was characterized genetic diversity by 5. cayotovora subsp. atposeptica (Eca)-specific PCR, PCR-RFLP of the two genes (16S rRNA and pel) and repetitive sequence PCR (ERIC-PCR). The results were compared with those of the other E. carotovora representative strains. None of the blackleg strains produced PCR amplicons with Eca-specific primers in contrast to the single 690 bp amplicon obtained with Eca strains. In addition, on the basis of pel gene RFLP with Sau3AI, the blackleg strains belonged to the pattern 2 whereas Eca strains belonged to the other one (pattern 3). By analysis of 16S rDNA RELP generated with HinfI, the most strains including the E. carotovera subsp. carotovora (Ecc) representative strains used in this study belonged to the pattern 1 whereas the blackleg strains belonged to the pattern 2 except for one strain. Moreover, ERIC-PCR analysis showed that the blackleg strains were closely related to each other and had an unique DNA band. Based on these molecular approaches, we have confirmed that the blackleg disease of potato is caused by a different E. carotovora from Eca and Ecc in Jeju island.