• Korean Journal of Environmental Agriculture
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• v.30 no.4
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• pp.382-389
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• 2011

BACKGROUND: Light-emitting diodes (LEDs) with lower electric cost and the specific wavelength have been considering as a novel light source for plant production in greenhouse conditions as well as in a closed culture system. Supplementary lighting for day-length extension was considered as light intensity, light quality, and/or photoperiod control on plant growth and development. Effects of supplementary blue or red LED radiation with lower light intensity on growth of Ageratum (Ageratum houstonianum Mill., cv. Blue Field), African marigold (Tagetes erecta L., cv. Orange Boy), and Salvia (Salvia splendens F. Sello ex Ruem & Schult., cv. Red Vista) were discussed during sunrise and sunset twilight in the experiment. METHODS AND RESULTS: Supplementary lighting by blue and red LEDs for 30 (Treatment B30; R30) or 60 (Treatment B60; R60) min. per day were established in greenhouse conditions. Photosynthetic photon flux for supplementary radiation was kept at $15{\mu}mol\;m^{-2}\;s^{-1}$ on the culture bed. Natural condition without supplementary light was considered as a control. The highest shoot and root dry weights were shown in African marigold exposed by red light for 60 min. per day. Supplementary blue and red lighting regardless of the radiation time significantly stimulated development of lateral branches in African marigold. Stem growth in Ageratum and Salvia seedlings was significantly promoted by red radiation as well as natural light. CONCLUSIONS: Extending of the radiation time at sunrise and sunset twilight using LEDs stimulated reproductive growth of flowering plant species. Different characteristics on growth under supplementary blue or red lighting conditions were also observed in the seedlings during supplementary radiation.

• The Korean Journal of Mycology
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• v.46 no.2
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• pp.200-204
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• 2018

Sclerotinia rot symptoms were frequently found on the stems of Aster yomena in the Gurye region of Korea in April 2016. The symptom, watery soft rot, mainly appeared on the stems, and severely infected plants blighted. White mycelia spread over the stems of the infected plants and the soil surface. Small black sclerotia formed on the plant lesions and inside the diseased stems. Incidence of the disease was as high as 20~80% in the A. yomena fields. Based on the morphological and molecular characteristics of the isolates, the fungi were identified as Sclerotinia minor. This is the first report of Sclerotinia rot caused by Sclerotinia minor on A. yomena in Korea.

• Journal of People, Plants, and Environment
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• v.24 no.3
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• pp.277-283
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• 2021

Background and objective: This study was conducted to increase understanding of agriculture through agricultural experience programs for adolescents living in self-reliance residence hall, and to investigate changes in work performance ability through changes in hand function. Methods: There were 11 subjects, and the average age was 18.2 years, all males without disabilities. The agricultural experience program consists of a total of 10 sessions including orientation and watching videos on future agriculture, creating vegetable gardens, planting, managing each crop, harvesting, visiting the processing room, and selling at a local food store. Results: The change in agricultural literacy by the agricultural experience program positively improved from a score of 113.73 to 127.91 (p = .008). The changes by sub-item are as follows. The value and safety of agri-foods (p = .020) and agriculture and natural environment (p = .007) were significantly improved. The function and value of rural areas (p = .050), production of agricultural products (p = .160), processing and distribution of agricultural products (p = .248), and agricultural policies (p = .058) were not significantly changed. The simple function of the hands was measured by the number of pegs inserted during 30 seconds, and the assembly function was measured by the number of pegs inserted during 60 seconds. In the case of simple function, the dominant hand was improved from 14.82 to 15.83 (p = .014), andthe non-dominant hand was also significantly improved from 13.79 to 15.01 (p = .002). There was no significant improvement in the simple function (p = .153) and assembly function (p = .770) of both hands. Conclusion: It is considered that the agricultural experience program will enable youths living in self-reliance residence halls to enhance their understanding of agriculture as an occupation, and enable them to play a role as wise consumers by positively affecting improvements in their agricultural literacy and simple hand functions.

• The Korean Journal of Pesticide Science
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• v.14 no.3
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• pp.241-246
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• 2010

Field experiments were carried out to establish economic threshold for com borer (Ostrinia furnacalis (Guen$\'{e}$e)) on waxy com plants by examining the number of adult insects caught in pheromone traps and the injury levels of waxy com which were artificially controlled. Adult com borers were lured into the pheromone traps during the whole growth period in five areas in Gangwon province including Chuncheon. The number of com borers trapped was the greatest in Chuncheon followed by Cheolwon and Hongcheon, and the same trend was observed for injury level of waxy com. Based on marketable yield data of waxy com plants related to the artificially-controlled injury levels at tassel stage, spray threshold was determined as the injury level of 11~15%, where the injury of com plants exceeded the economically admitting level.

• BMB Reports
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• v.42 no.1
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• pp.16-21
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• 2009

Three novel Class A genes that encode heat shock transcription factor (HSF) were cloned from Oryza Sativa L using a yeast hybrid method. The OsHSF7 gene was found to be rapidly expressed in high levels in response to temperature, which indicates that it may be involved in heat stress reception and response. Over-expression of OsHSF7 in transgenic Arabidopsis could not induced over the expression of most target heat stress-inducible genes of HSFs; however, the transcription of some HSF target genes was more abundant in transgenic plants following two hours of heat stress treatment. In addition, those transgenic plants also had a higher basal thermotolerance, but not acquired thermotolerance. Collectively, the results of this study indicate that OsHSF7 might play an important role in the response to high temperature. Specifically, these findings indicate that OsHSF7 may be useful in the production of transgenic monocots that can over-express protective genes such as HSPs in response to heat stress, which will enable such plants to tolerate high temperatures.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.187-187
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• 2017

Cadmium (Cd) pollution is rapidly increasing in worldwide due to industrialization and urbanization. In addition to its negative effects on the environment, Cd pollution adversely affects human health. Rice (Oryza sativa L.) is an important agricultural crop worldwide, including South Korea, and studies have examined its ability to alleviate Cd uptake from the soil into plants. However, information about the relationship between sulfur (S) and antioxidants in rice seedlings is still limited with regard to Cd phytotoxicity. We therefore investigated the changes in reactive oxygen species (ROS) and antioxidants in rice (Oryza sativa L. 'Dongjin') seedlings exposed to toxic Cd, S treatment, or both. The exposure of rice seedlings to $30{\mu}M$ Cd inhibited plant growth; increased the contents of superoxide, hydrogen peroxide, and malondialdehyde (MDA); and induced Cd uptake by the roots, stems, and leaves. Application of S to Cd-stressed seedlings decreased Cd-induced oxidative stress by increasing the capacity of the glutathione (GSH)-ascorbate (AsA) cycle, promoted S assimilation by increasing cysteine, GSH, and AsA contents in treated plants, and decreased Cd transfer from the roots to the stems and leaves. In conclusion, S application of plants under Cd stress promoted Cys and GSH biosynthesis and GSH-AsA cycle activity, thereby lowering the rate of Cd transfer to plant shoots and promoting the scavenging of the ROS that resulted from Cd toxicity, thus alleviating the overall Cd toxicity. Therefore, these results provide insights into the role of S in regulating the tolerance, uptake, and translocation of Cd in rice seedlings. The results of this study indicate that S application should have potential as a tool for mitigating Cd-stress in cereal crops, especially rice.

• The Plant Pathology Journal
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• v.16 no.6
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• pp.297-305
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• 2000

Weeds are widely grown in the field and are infected by many viruses. A survey was conducted to identify viruses infecting weeds in Korea. Virus-infected weed samples including Rorippa indica (L.) Hiern, R. islandica (Oed.) Bord, Crepidiastrum denticulatum (Houtt.) Pak & Kawanno, Achyranthes japonica (Miq.) Nakai, and Chrysanthemum boreale (Makino) Makino were collected in Kyonggi Province. These weeds were grown in the greenhouse and were isolated on 10 test plants. Several virus isolates were isolated fron infected tissues and were further studied by host range assay, serological test, electron microscopy (EM), reverse transcription-polymerase chain reaction (RT-PCR) and sequencing. Each isolated virus strain was mechanically transmitted to weeds and various hosts including Nicotiana spp., Brassica spp., Vigna unguiculata, Capsicum annuum, and Cucumis sativus and showed systemic mosaic, vein clearing, necrosis, mottle, malformation, chlorosis, and/or death of host plants in some cases. Each virus was then purified using infected leaves and observed by EM. From these results three viruses were isolated and identified as Turnip mosaic virus (TuMV), Broad bean wilt virus (BBWV), and Cucumber mosaic virus (CMV). RT-PCR using virus-specific oligonucleotide primers and the cloning were conducted to determine the nucleotide sequences of coat proteins of the three viruses their amino acid sequence were deduced. The amino acid sequence homologies were about 92.7 to 99.7%, 96.2 to 97.7%, and 93.9 to 98.6% to other reported TuMV, BBWV, and CMV strains, respectively. These results suggest that many weeds may serve as primary inoculum source of diseases caused by TuMV, BBWV, CMV and that the management of these viral diseases can be achieved through weed control.

• Molecules and Cells
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• v.19 no.1
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• pp.16-22
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• 2005

A cDNA encoding ${\gamma}-tocopherol$ methyltransferase (${\gamma}-TMT$) from Arabidopsis thaliana was overexpressed in lettuce (Latuca sativa L.) to improve the tocopherol composition. Seven lines of lettuce ($T_0$) containing the ${\gamma}-TMT$ transgene were produced by Agrobacterium-mediated transformation. The inheritance and expression of the transgene were confirmed by DNA and RNA gel blot analyses as well as quantification of tocopherols and ${\gamma}-TMT$ activities. The ratio of ${\alpha}-/{\gamma}-tocopherol$ content (TR) varied from 0.6 to 1.2 in non-transformed plants, while the $T_0$ plants had ratios of 0.8 to 320. The ratio ranged from 0.4 to 544 in 41 $T_1$ progenies of the $T_0$ transgenic line gTM3, and the phenotypic segregation indicated monogenic inheritance of the transgene (i.e., 3:1 = dominant:wild-type classes). There was a tight relationship between the TR phenotype and ${\gamma}-TMT$ activity, and enzyme activities were affected by the copy number and transcript levels of the transgene. The TR phenotype was stably expressed in $T_2$ progenies of $T_1$ plants. The results from this study indicated that a stable inheritance and expression of Arabidopsis ${\gamma}-TMT$ transgene in lettuce results in a higher enzyme activity and the conversion of the ${\gamma}-tocopherol$ pool to ${\alpha}-tocopherol$ in transgenic lettuce.

• Korean journal of applied entomology
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• v.50 no.3
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• pp.215-220
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• 2011

This study aimed to estimate control thresholds for managing common cutworm, Spodoptera litura Faricius (Lepidoptera: Noctuidae) at different larval densities and growth stages of Chinese cabbage in field conditions. The percent yield reduction (Y) of Chinese cabbage infested by different densities of S. litura (X, no. of larvae/100 plants) for three weeks were estimated by Y=-21.85X+1300 (R2=0.997) 5 days after transplanting and Y=-12.1X+1382 (R2=0.998) 20 days after transplanting. Based on the relationships between the densities of S. litura larvae and the yield index of chinese cabbage, the number of larvae (2nd to 3rd instar) which caused 5% loss of yield was estimated as 2.9/100 plants 5 days after transplanting, and 5.6/100 plants 20 days after transplanting.

• Journal of Crop Science and Biotechnology
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• v.11 no.3
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• pp.193-198
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• 2008

To develop a natural re-seeding technology, the optimum soil incorporation time of Chinese milk vetch(CMV) plant residues, seed persistence in soil, biomass production and subsequent rice yield were determined from 2005 to 2007 in rice with CMV green manure in southern Korea. Generally, insufficient seedling stand was regenerated with CMV incorporation to the soil at 20 and 25 days after flowering(DAF), while high regeneration of greater than 400 seedlings per $m^2$ was observed at 35 and 40 DAF. High re-seeding stand of CMV incorporated at 35 DAF or later was related with high seed viability and heavy seed weight. Appreciable number of CMV seeds remained 4 month after burial in soil and a good number of CMV seedlings regenerated from this seed bank at rice harvest time in the fall. Based on the relationships among re-seeding number of CMV plants, seed weight and seed viability, CMV plants should be incorporated into the soil 35 DAF(May 30) or later when CMV seeds were sufficiently matured. The natural re-seeding stand for the 3-year trials was stable ranging from 437 to 700 plants per $m^2$ and the biomass production was sufficient to supply nitrogen for rice growth. The use of re-seeding CMV plant can produce similar rice yield like that of rice without CMV green manure.