• Proceedings of the Korean Society of Crop Science Conference
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• 2005.08a
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• pp.57-74
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• 2005

Rice yield and protein content have been shown to be highly variable across paddy fields. In order to characterize this spatial variability of rice within a field, the two-year experiments were conducted in 2002 and 2003 in a large-scale rice field of $6,600m^2$ In year 2004, an experiment was conducted to know if prescribed N for site-specific fertilizer management at panicle initiation stage (VRT) could reduce spatial variation in yield and protein content of rice while increasing yield compared to conventional uniform N topdressing (UN, ,33 kg N/ha at PIS) method. The trial field was subdivided into two parts and each part was subjected to UN and VRT treatment. Each part was schematically divided in $10\times10m$ grids for growth and yield measurement or VRT treatment. VRT nitrogen prescription for each grid was calculated based on the nitrogen (N) uptake (from panicle initiation to harvest) required for target rice protein content of $6.8\%$, natural soil N supply, and recovery of top-dressed N fertilizer. The required N uptake for target rice protein content was calculated from the equations to predict rice yield and protein content from plant growth parameters at panicle initiation stage (PIS) and N uptake from PIS to harvest. This model equations were developed from the data obtained from the previous two-year experiments. The plant growth parameters for this calculation were predicted non-destructively by canopy reflectance measurement. Soil N supply for each grid was obtained from the experiment of year 2003, and N recovery was assumed to be $60\%$ according to the previous reports. The prescribed VRT N ranged from 0 to 110kg N/ha with average of 57kg/ha that was higher than 33kg/ha of UN. The results showed that VRT application successfully worked not only to reduce spatial variability of rice yield and protein content but also to increase rough rice yield by 960kg/ha. The coefficient of variation (CV) for rice yield and protein content was reduced significantly to $8.1\%\;and\;7.1\%$ in VRT from $14.6\%\;and\;13.0\%$ in UN, respectively. And also the average protein content of milled rice in VRT showed very similar value of target protein content of $6.8\%$. Although N use efficiency of VRT compared to UN was not quantified due to lack of no N control treatment, the procedure used in this paper for VRT estimation was believed to be reliable and promising method for managing within-field spatial variability of yield and protein content. The method should be received further study before it could be practically used for site-specific crop management in large-scale rice field.

• Korean Journal of Environmental Agriculture
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• v.10 no.1
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• pp.51-57
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• 1991

Field experiments were carried out to evaluate the utility of water hyacinth(Eichhornia crassipes Solm-Laub) for purifyng sewage water in paddy fields of $247m^2$(75 Pyung). A field was lined with PVC film at a depth of 30cm and sewage water for 40 days. The results obtained with the use of water hyacinth in the sewage water are summarized as follows : 1. The Sodium linear dodecyl benzene sulfonate content of sewage water on the inlet was 6.33 ppm, themiddle point was 3.50 ppm and the outlet was 1.37 ppm. 2. With the use of water hyacinth in the sewage and the distilled water, the L.A.S. content were decreased from 7.3 and 4.0 to 0, respectively. 3. Sterillization with 70% ethyl alcohol at the roots of the water hyacinth was reduced the degradation effect of L.A.S. 4. The COD and $NH_4^+-N$ content of the sewage decreased from 107 and 32.7 ppm to 32.6 and 16.2 ppm, respectively and the P, Na and Cl content also were reduced.

• Korean Journal of Environmental Agriculture
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• v.2 no.2
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• pp.108-113
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• 1983

There has been two kind of research fields in evaluating the ecotoxicity of chemicals The one is a bioassay and the other is an ecosystem analysis. The toxicants are transported into different biota, which have quite different environmental behaviour patterns and toxic properties. The effects of pesticides (butachlor, carbofuran, and tricyclazole) on periphyton community was studied by analyzing content of chlorophyll-a and autotrophic index (AI) that is a means of determining the trophic nature of the periphyton community. Results indicated that the content of chlorophyll-a was not influenced by the pesticides. The growth of algae was inhibited by sunshine period. And AI value is 43-2027: the large value indicates heterotrophic periphyton community, and was not affected by pesticides.

• Korean Journal of Agricultural and Forest Meteorology
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• v.21 no.4
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• pp.229-237
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• 2019

This study was conducted to estimate annual reference evapotranspiration (ET₀) for the agro-climatic zones for rice paddy fields in South Korea between 1980 and 2015. The daily ET₀ was estimated by applying the Penman-Monteith method to meteorological data from 61 weather stations provided by Korean Meteorological Administration (KMA). The average of annual ET₀ from 1980 to 2015 was 1334.1±33.89 mm. The ET₀ was the highest at the Southern Coastal Zone due to their higher air temperature and lower relative humidity. The ET₀ had significantly increased with 2.81 mm/yr for the whole zones over 36 years. However, the change rate of it was different among agro-climatic zones. The annual ET₀ highly increased in central zones and eastern coastal zones. In terms of correlation coefficient, the temporal change of the annual ET₀ was closely related to variations of four meteorological factors (i.e., mean, minimum temperatures, sunshine duration, and relative humidity). The results demonstrated that whole Korean agro-climatic zones have been undergoing a significant change in the annual ET₀ for the last 36 years. Understanding the spatial pattern and the long-term variation of the annual ET₀ associated with global warming would be useful to improve crop and water resource managements at each agro-climatic zone of South Korea.

• Korean Journal of Ecology and Environment
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• v.44 no.2
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• pp.178-186
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• 2011

This study was conducted to investigate runoff characteristics of non-point pollutant sources in an agricultural area watershed in Boeun area, Chungbuk Province. The monitoring site represented 1.56 $km^2$, about 44.4% of which was covered with paddy fields. The monitoring was conducted for six events in a period of 5 month. Event Mean Concentration (EMC) and Site Mean Concentration (SMC) of suspended solids (SS), biochemical oxygen demand (BOD), chemical oxygen demand (COD), total nitrogen (T-N) and total phosphorus (T-P) were calculated using the results of the water quality parameters. A comparison between arithmetic mean concentration and EMC revealed that nearly all EMCs were higher than the corresponding arithmetic mean concentrations. First-flushing effects were exhibited for SS, BOD, and T-P, with relatively high concentrations in early-stage storm events.

• Journal of Ginseng Research
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• v.20 no.4
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• pp.472-500
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• 1996

Researches on mineral nutrition, physiology and phyrsiological diseases, . cultivaction methods. brceding. pest control quality management and extension during 1976-1995 in Korea were reviewed Review in brceding and pest control was restricted to the researches directely related to cultivaction. Mineral nulrient up take. partion and varicos factors such as top dreasing. Light intersity etc. and interrelationship between minerals were investigated. Top dressing was not effective due to low minera1 requorement Physiological characteristics on tempelature light and water were well elucidated and applied to assess traditional cultivation method and its inovation. Photosyrnthetic pigments. light harvest proteins and activity of related enzymes were studied. In nitrogen metabolism arginine, praline, ammonium, threonine appeared to have important role in re growth of shoot Saponin metabolism was studied in relation to growth and new ginsenosides were found but physiological role of saponin was not clearly elucidated yet Endogenous growth regulators were reported and various erogenous growth regulators were studied for growth stimulation. short stem and seed pruning etc. Various physiological diseases were investigated for cause and control measures were established. Water culture was little studied Forest culture was studied but not retched the recommendable stage Drip irrigation straw mulching. seasonal shading and soil preparation method including soil fertility adjustment were established for practical application. Shading materials completely changed to polyethylene net and materials of polymers The research on ginseng cultivation in paddy field opened the way to establish the permanent ginseng cultivation plantation Ginseng harvester and seeder were developed in the late 1950s. Transplanted and many other machines were developed in the early 1990s. In ginseng breeding only pure line selection was of practical significance several verities were at the stage of seed propagation at ginseng plantations. Mutation breeding (${\gamma}$-ray. X-ray chemicals) was not successful. The research on plantlet formation through tissue culture was a little progressed but still far behind to vegetative propagation. Disease control research was concentrated in the isolation and identification of pathogans. their ecological charactelistics and biological control and soil humigation. Potato root rot nematodes was found and control method was established. Insect and small animal control research was greatly progresses in identification, ecological investigation, and ecological and physical control. Weed control was less important due to the development of mulching method of ridge and ditch. Quality factors of raw ginseng in relation to red ginseng process were extensively studied. Traditional quality measures were elucidated in accordance with modern analytical chemistry resulting in the importance of peptides in the centrat part rather than ginsenosides For large root production growth promoting rootzone micrcorganisms (PGPRM) were isolated and active compounds were identified. Field test on PGPRM was on going. Varictus methods formality improvement through cultivation were developed. Management research of ginseng production was rare Extension was active throuch official and private organizations and through workshop for the extension specialists, and direct lectures to grower's. Extension services made the researcher to understand the existing problems at grower's fields. Research environment for ginseng production was in prime time only for three years when Korea Ginseng Research Institute was established then gradually aggravated.

• Korean Journal of Weed Science
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• v.18 no.1
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• pp.12-19
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• 1998

The pattern of rice cultivation in Korea is changing from hand transplanting and machine transplanting into direct-seeding for low input and cost-down practices. However, there are still some obstacles to establish the direct-seeding cultural practices because of poor seedling stand, lodging, and weed infestation. In particular, there were much more and wide weed occurrence in direct-seeding rice as compared with the transplanted rice. Weed occurrence in terms of dry weight of weeds was highest in dry direct-seeded rice followed by sowing an puddled soil, sowing on submerged soil in order as compared with transplanting with infant rice seedling. Echinochloa crux-galli was a common dominant weed with 35~44% distribution in any direct-seeding methods. The dominant weed species were E. crux-galli, Cyperus difformis, C. serotinus, and Ludwigia prostrata in dry-seeded rice. The dominant weed species in water-seeded rice were E. crus-galli, Eleocharis kuroguwai, Scirpus juncoides, and Monochoria vaginalis. Yield loss of rice due to weeds at weedy condition was 96% in dry direct-seeded rice. In water-seeded rice, yield loss was 61%, whereas yield loss was 40% in machine transplanting with infant rice seedling.

• Korean Journal of Microbiology
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• v.46 no.2
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• pp.157-161
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• 2010

Photosynthetic purple nonsulfur bacterial strains were isolated from the sediments collected from rice paddy fields and sludges of wastewater treatment plant, and their plant growth promoting capabilities were examined. Most well known phytohormones, auxin such as indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) and 5'-aminolevulinic acid (ALA) were detected by HPLC in the culture broth of these isolates. Among the isolated bacteria, Rhodopseudomonas faecalis D15 showed the highest production rate of 769.8 ${\mu}g$/mg protein of IAA, 1323 ${\mu}g$/mg protein of IBA and 7.4 mM/mg protein of ALA in the modified Biebl and Pfennig's medium. R. faecalis C9 showed the highest production rate of 20.82 ${\mu}g$/mg protein of gibberellin. In consequence, the root length and dry weight of the germinated tomato seedling treated with R. faecalis isolates were longer and heavier than those of uninoculated control after 15 days of incubation in the soil. Especially, the dry weight of germinated tomato seedling increased by 119.4% in C9-treated samples after 15 days. These purple nonsulfur bacteria may be utilized as environment-friendly biofertilizer in the agriculture.

• Korean Journal of Medicinal Crop Science
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• v.6 no.3
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• pp.232-238
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• 1998

To analyse the management and production of medicinal crops in Uisong region, cultural conditions and standard income of 147 farms were investigated. Location quotient of medicinal crops cultivated was high as following order ; Paeonia lactiflora > Cornus ofidnalis> Bupleurm falcatum > Anemarhena asphodeloides > Rehmannia glutinosa > Eucommia ulmoides > Paeonia suffruticosa > Angelica dahurica. The average cultivated area per farm was 1.92ha : 1.35ha of upland field, 0.56ha of paddy field. Distribution of agricultural land in each farm was average 10.2 fields in 3.1 locations. Ratio of labor input in the medicinal plant sector was 31.1 %. The number of medicinal crops cultivated was 36 species among 147 farms and 2.4 species per farm. Among the cultivated medicinal plant, peony (Paeonia lactiflora) was the most popular medicinal plant, which was cultivated in 30.72ha of 85 farms. Income from medicinal plants was high in order of Carthamus tinctorius, Polygonatum stenophyllum, Angelica genuilexa. Medicinal crops should be selected based on farm condition, risk level and price settlement in order to maximize productivity and income.

• Journal of Korean Society of Forest Science
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• v.86 no.1
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• pp.46-55
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• 1997

This study tried to categorize the types of mountain-village areas in terms of some key variables representing the socio-economic and natural characteristics in order to provide basic information for policy formation of mountain areas. Cross-sectional data of the year 1990 for 900 sub-counties were collected to analyse the characteristics of mountain-village areas. Eleven variables were selected to classify the types of sub-county levels. According to the results of the study, the socio-economic conditions of mountain-village areas represented by the number of corporations, number of non-farming households, and population density of mountain-village areas were found to be inferior to other parts of the nation while the proportion of forest land, share of non-paddy crop fields, distance from cities, percentage of farming households, and elevation from the sea-level were higher to the other areas. By the principal factor analysis, the key variables representing industrial development, mountain-ousness, and accessibility from near cities were selected. By a cluster analysis employing the selected variables, 5 different types of mountain-village areas were categorized.