• The Plant Pathology Journal
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• v.15 no.6
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• pp.335-339
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• 1999

Citrus tristeza virus(CTV), an aphid-borne closterovirus, is one of the most destructive pathogens of citrus. It has caused rapid decline in growth, stem pitting and death in citrus trees. A reverse transcriptase polymerase chain reaction (RT-PCR) assay was developed for detection of CTV and investigation of the CTV infection status of citrus and its related cultivars in Cheju island. For RT-PCR based CTV detection, primers were designed to amplify 670bp of coat protein gene. A screening test for CTV in citrus cultivars was conducted from March to July in 1999. Seventy individual citrus trees representing 9 species of 3 genera were tested. The infection rates of CTV for leaves from the years or older trees of late maturing citrus varieties such as Yuzu (C. junos Sieb. ex Tanaka), Navel orange (C.sinensis Osbeck), Kiyomitanger (C. unshiu x C. sinensis), and Shiranuhi ((C. unshiu x C. sinensis) x C. reticulata) were 100%, 80%, 60%, and 60% respectively. The CTV infection rates in Early satsuma mandarins such as 'Miyagawa Early' Satsuma mandarins (C. unshiu Marc. var. Miyagawa) and 'Okitsu Early' Satsuma mandarins (C. unshiu Marc. var. Okitsu) were 100%, and 60%, respectively. CTV was not detected in Cheju native Dangyooja (C. unshiu Marc. var. Osbeck), Trifoliate orange (Poncirus trifoliata) and Kumquat (Fortunella margarita Swingle). In conclusion, RT-PCR assay can be successfully applied to the detection of CTV in citrus trees.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.3
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• pp.216-222
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• 1994

Experiments were conducted in the research field of the former Wheat and Barley Research with three barley cultivars, Olbori, kangbori and Suwon 18, which show different growth characteristics. Relationships between the degree of grain filling and the functions of photosynthetic organs in grain growth post-anthesis were investigated by removal treatment of awns and leaves, Stems and leaf sheath contributed to final grain weight invariably with cultivars by 79.2∼81.4%. while the contribution rate of awns and leaf blades varied by different cultivars, Awns contributed by 11.6∼13.8% in 'Olbori' and 'Kangbori', and 5.4% in 'Suwon 18', Contribution of leaf blades was 15.4% for 'Suwon 18', and 4.8∼8.1% for other cultivars, Of leaf blades upper ones showed a higher contribution rate, Early-maturing cultivars which maintain leaf greenness to the late phase of grain growth or awned cultivars were considered advantageous in grain filling.

• Korean Journal Plant Pathology
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• v.1 no.3
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• pp.169-172
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• 1985

Natural sclerotia of Rhizoctonia solani causing rice sheath blight were inoculated at 10 day intervals from June 15 to July 15 in paddy field, Icheon, Korea. Percentage of infected stems, top lesion height and percentage of. lesion height vs. plant height were higher in the early inoculated plots than in the late inoculated ones. However, rio significant differences among inoculation dates of sclerotia were found on the basis of degree of damage at maturing stage and rice yield. These results suggest that the time of initial symptom appearance under the same inoculum potential may not affect the damage of rice plants by the fungus.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.2
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• pp.121-129
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• 1987

Indonesian varieties were compared with Korean varieties on three different sowing times, each of which had three different nursery periods, at Suwon, Korea (126$^{\circ}$ 19'E and 37$^{\circ}$ 16'S). Indica-type varieties with exception of late-maturing ones had heading regardless of sowing time and nursery period. As the Korean varieties com-pared with those, the earlier sowing plots with shorter period of nursery gave better result in yields and yield components.

• Korean journal of applied entomology
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• v.31 no.2
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• pp.174-181
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• 1992

Early, mid, and late maturing soybean varieties were artificially infested with larvae of Delia platura at seeding, and then later development and productivity of soybeans were studied. In addition, in hope to utilize as possible tactics in the management of D. platura in soybeans, cultural factors such as contents of organic matter in soil, soil types, and the use of plastic mulching on the degree of damage to soybean plants by D. platura were examined. Primary leaf damage by the larva delayed the forthcoming vegetative growth but not the blooming which is initiated by the change in day length. Degree of delay in growth was more severe where leaf damage was induced by insect infestation than where artificially excised, apparently owing to simultaneous damage in stems and roots besides primary leaves. Productivity of soybeans also dropped significantly in plants with 25 % or more loss in the primary leaf area by the larva. Both transparent and black plastic mulchings shortened the period from seeding to emergence of soybean thus reducing the chance of possible attack by the larva. Soybean seedlings grown in clay loam or clay were attacked less by the larva than those in other types of soil. High organic matter content in the soil enhanced speed of emergence resulting in less larval damage to the seedling.

• Korean Journal of Medicinal Crop Science
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• v.1 no.2
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• pp.162-165
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• 1993

To determine optimal sowing date of Job's Tears in southern-Region of Korea,Job's Tears cv. Local cultivars Ewon and Heuksuk were grown under the three different sowing dates. As sowing date was delayed, the heading and maturing date were delayed also and yield components such as plant height, stem diameter, number of stems, weight of 100grains and that of 1 l, etc. were the highest at the sowing date of Apr. 15. Yield of stem and seed were the heaviest in Apr. 15 seeding and they were light in the early or late sowing, Judging from the results reported above, optimum seeding date of Job's Tears seemed to be Apr. 15.

• Proceedings of the Korean Society of Crop Science Conference
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• 1998.10a
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• pp.313-335
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• 1998

If the atmospheric concentrations of greenhouse gases double, the annual temperature increase in mean surface temperature relative to 1990 will be about 2.0 to $2.5^{\circ}C$ and the annual precipitation increase about $15{\%}$ by 2100 in Korea. When the temperature rises $2^{\circ}C$, the annual temperature will be $13^{\circ}C,\;15^{\circ}C,\;and\;16^{\circ}C$ in Western Central, Yeongnam Basin, and Southern Coastal respectively. Consequently the crop period could be prolonged $10{\~}29$ days. In the case of gradual global warming, annual crops could be adapted to the changed environment by breeding, and the perennial crops should be shifted to ether area. If global warming happens suddenly over the threshold of atmospheric greenhouse gases concentration, then we shall have disturbance of ecosystem. When $2^{\circ}C$ higher than present, the optimum flowering date of rice plant delayed about 10 days, so it may not possible to adopt the fate with present japonica rices, therefore, the recommended characteristics of rice varieties are longer basic vegetative period, more late maturing and higher ripening temperature. Barley and wheat crops could be shifted to northern coastal areas and apple production areas should be shifted to those areas under $13.5^{\circ}C$ in annual mean temperature at global warming. Ideotypes of crops under climate changes should have such ecological characteristics that are indispensable to accomplish the sustainable agriculture under increased $CO_{2}$ and temperature condition as the diversification of genetic resources from yield-oriented to biomass-oriented characteristics with the higher potentials of $CO_{2}$ absorption and Primary production. In addition, a heat-tolerance, a pest resistance, an environmental adaptability and a production stability should be also incorporated collectively into our integrated agroecosystem.

• Korean Journal of Environmental Agriculture
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• v.34 no.3
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• pp.210-216
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• 2015

BACKGROUND: In korea, sweet persimmon(Diospyros kaki) cultivation is front to abiotic stresses such as frost damage at fruit maturing stage. The cold and rapid freezing stresses are most damaging to fruit production which is most actively progressed in late fall. This study was performed to evaluate the validity of chlorophyll fluorescence imaging(CFI) technology to determine the degree of frost damage in sweet persimmon fruits. METHODS AND RESULTS: The sweet persimmon fruits were measured separately for each treatment(15, 30, 60 minutes) at 24 hours after treatment(HAT) rapid freezing. A CFI FluorCam (FC 1000-H, PSI, Czech Republic) was used to measure the fluorescence images of the fruits. In rapid freezing for 15 minutes, photochemical parameters were not changed. However, in rapid freezing for 30 and 60 minutes, photochemical parameters were lowered. Especially, $F_m$, $F_v$, $F_v/F_m$ and ${\Phi}PSII$ values were declined under rapid freezing. CONCLUSION: In our study, it was clearly indicated that the rapid freezing could be a stress in sweet persimmon fruits. The CFI analysis and its related parameters are applicable as a rapid assessing technique for the determination of frost damage.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.145-145
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• 2022

South Korea greenhouse gas emissions have increased year by year, resulting in a total emission of 727.6 million tons of CO₂ eq in 2018, a 2.5% increase compared to 2017. Among them, the agricultural sector emitted 21.2 million tons of CO₂ eq., accounting for 2.9% of the total. Among the greenhouse gases emitted from the agricultural sector, a particularly problematic is methane gas emitted from rice paddies. Methane is one of the important greenhouse gases with a global warming potential (GWP) that is about 21 times higher than that of carbon dioxide due to its high infrared absorption capacity despite its relatively short remaining atmospheric period. Since the pattern of methane generation varies depending on the rice variety and ecological type, research related to this is necessary for accurate emission calculation and development of reduction technology. Accordingly, a study was conducted to find out the changes in greenhouse gas emission according to rice varieties and ecology types. As for the rice eco-type cultivar, early maturing cultivar (Haedamssal) and medium-late rice cultivar (Saeilmi) were used. Haedamssal was transplanted on May 25 and June 25, and Saeilmi was transplanted on June 10 and June 25. The amount of methane generated according to the growing day showed a tendency to increase as the planting period was earlier. The difference between varieties was that Haedamssal showed higher methane production than Saeilmi. The total CH₄ flux in the saeilmi was 18.7 kg·h^-1(Jun 10 transplanting), 12.4 kg·h^-1(Jun 25 transplanting) during rice cultivation. Lower methane emission was observed in Saeilmi than in Haedam rice. In addition, the earlier the planting period, the higher the methane emission. This study is the result of the first year of research, and it is planned to investigate the amount of greenhouse gas emission between double cropping and single cropping using wheat cultivation after harvest for each ecological type.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2023.04a
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• pp.66-66
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• 2023

만감류 5종(한라봉, 천혜향, 황금향, 레드향, 카라향) 부위별 에탄올 추출물의 항산화 활성에 관하여 총 폴리페놀 함량 측정, 총 플라보노이드 함량 측정, DPPH radical 소거 활성 실험을 실시하였다. 만감류 5종(한라봉, 천혜향, 황금향, 레드향, 카라향)의 총 폴리페놀 함량의 경우, 레드향 과피 처리구(93.97mg/g)에서 가장 높았으며, 천혜향을 제외한 모든 만감류 품종 부위들 가운데, 과피 처리구에서 높은 폴리페놀 함량을 나타내었다. 만감류 5종(한라봉, 천혜향, 황금향, 레드향, 카라향)의 총 플라보노이드 함량은 한라봉 전체 처리구(23.65mg/g)에서 가장 높았으며, 모든 처리구에서 30mg/g 함량보다 낮은 결과를 나타내어 총 폴리페놀 함량 대비 낮은 함량을 나타내었다. 이러한 현상은 만감류 5종(한라봉, 천혜향, 황금향, 레드향, 카라향) 가운데 과피 두께의 비율이 영향을 미친 것으로 판단되어진다. 만감류 5종(한라봉, 천혜향, 황금향, 레드향, 카라향)의 DPPH radical 소거 활성의 경우, 한라봉 전체(81.01%)를 시작으로 한라봉 중피(73.13%), 한라봉 외피(63.94%) 처리구에서만 DPPH radical 함량이 EDA 50% 이상 값을 나타내었다. 특히 총 폴리페놀 함량(mg/g)과 총 플라보노이드 함량(mg/g) 모두에서 높은 수치를 기록했던 처리구들 가운데 한라봉 중피(79.75, 23.16), 한라봉 전체(75.51, 23.65) 처리구에서 높은 항산화 활성을 보인 반면, 레드향 과피(93.97, 20.59)의 활성은 49.26%로 DPPH radical EDA 50%에 미치지 못하였다. 이러한 결과는 과피와 과육의 에센셜 오일과 성분의 차이에서 기인된 것으로 추측된다.