• Korean Journal of Soil Science and Fertilizer
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• v.45 no.2
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• pp.215-222
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• 2012

This experiment was conducted to clear up the cause of nutrient physiological disorder and to manage of optimum fertilization for leaf perilla crop under plastic film house condition in Geum-san area in 2009. A nutrient contents of leaf perilla were analyzed during the growing stages of crop from the first harvest to the last harvest stages, and the data were going to use as the nutritional factors for farms' activity in the fields. In survey of leaf perilla growing status at five farmers' fields, it was needed 30 days for growing of 5~10 stems, 60 days for 10~15 stems and 45 days for 15~20 stems of leaf perilla. Contents of nitrogen, phosphorus and potassium in leaf and stem had been kept on some high values in early stages, but it had been decreased in gradually in late stages of growing. Nitrogen and potassium contents were more changeable in leaf than stem, and phosphorus content was kept in more both of leaf and stem than those of nitrogen and potassium. The major macro-nutrient contents of perilla leaf on first of July were 6.34 in N, 0.54 in P, 2.48 in K, 1.98 in Ca and 0.62% in Mg, total uptake amounts of major three elements were $400kg\;ha^{-1}$ in N, $30kg\;ha^{-1}$ in P and $250kg\;ha^{-1}$ in K. Total yield of perilla leaf was $52,000kg\;ha^{-1}$, and total dry matter was $10,510kg\;ha^{-1}$ with $8,680kg\;ha^{-1}$ in leaf dry matter and $1,830kg\;ha^{-1}$ in stem dry matter.

• Journal of Wetlands Research
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• v.18 no.4
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• pp.465-473
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• 2016

This study was carried out to evaluate restoration process of a few wetlands in the National Institute of Ecology (NIE). Wetlands were composed of the former rice paddies that passive restoration was led through only natural process and by creating waterway, and an ecological pond, a reservoir that restorative treatment was practiced. As the result of analysis on landscape change in the current wetland space, existing wetland in NIE was usually from the former rice field and some parts were from the residential area or forest. Change of species composition was progressed from crops or ruderals resistant to human interferences to plant species, which has removed artificially for cultivation and grow usually in the typical wetland. Both species diversity and occurrence of exotic plants were the highest when restoration project is in progress and stages after and before restoration were followed. In an ecological pond that restorative treatment was done, vegetation introduced as riparian buffer was established successfully and thereby it was expected that it could contribute to buffer environmental stress comming from the outside. Synthesized the above mentioned results, change of wetland vegetation established in NIE resembled the typical trend of early successional stage occurring in the abandoned rice paddy and consequently, it was estimated that successful restoration is under progress. Restoration under progress in an ecological pond where artificial aid in the least level was added, could be evaluated in successful as well. In particular, successful establishment of buffering vegetation, which can play diverse ecological functions, could be evaluated as significant restoration effect. But adaptive management to improve ecological quality for the section that buffering vegetation is insufficient, is required.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.59 no.4
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• pp.511-520
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• 2014

Kenaf (Hibiscus cannabinus L.) was recognized as a potential source of forage. To reduce the production cost, we should insure large cultivation area. The one of the best candidate places to expand the useful kenaf production was 'Saemangeum' reclaimed land. To confirm the possibility of kenaf growth in reclaimed land, we seeding and cultivated the kenaf in 'Saemangeum'. The germination percentage of kenaf on 5.0 dS/m soil salinity was 18%. It is less 66% than that of 4.0 dS/m soil salinity and at 6.0 dS/m, the germination percentage of kenaf was under 10%. The growth and development of kenaf in reclaimed land grew worse with increasing soil salinity. The stem diameter which the most important factor that decide the value and yield of product was upper 2.6 cm when soil salinity maintained under 4.0 dS/m, but if soil salinity marked over 4.0 dS/m, the stem diameter of kenaf was drop under 2.0 cm and it deteriorate the number of leaves per plant by 20~46%. The necrosis on older tip and marginal leaves were noted approximately first month after seeding which was correlated directly with the salinity levels of reclaimed soil. Reduction of total yield was coincide with increasing levels of EC. If soil salinity over 5.0 dS/m, the amount of decreased by soil salinity was 51% than that of non-reclaimed region. The allowable soil salinity level of which could be maintained within 20% reduction rate was 4.2 dS/m. Consequently kenaf can be grown successfully with moderately saline soil condition. However, salt levels in excess of 4.2 dS/m severely have restricted plant growth and development and will result in significant yield reduction.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.60 no.3
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• pp.318-332
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• 2015

The maize production in South-eastern Asian countries showed a continuous increase with increasing poultry-livestock from the beginning of the 1990s to early 2010. Also the need for a new variety development of each contries was increased rapidly in the same period. Single-Cross hybrid varieties have been developed and supplied from 2001 instead of multi-cross maize varieties since 1992 in Indonesia. In Cambodia, CP group is mainly manufacturing feeds with most of the forage maize from farmers who are growing its seeds from the company. Cambodian main cultivars are varieties of multinational corporations such as DK8868 from Monsanto, NK6326, NK7328 from Syngenta and CP333 from CP group including local business company. Vietnam is the main maze importing country in South-Eastern Asia which had imported 13 times scale of amount compared to exports in average from 1990 to 2011. Vietnamese government has developed a range of varieties for improving their efficiency in production, such as the LVN-10 with political investments. Their production has been reached to 80% of the total. According to the 2012 MIFAFF (Ministry for Food, Agriculture, Forestry and Fisheries) data in Korea, domestic edible maize cultivation area was approximately 15,000ha. It showed 74,399 tons of production, 3.8% of food self-sufficiency in maize and around 0.9% of grain self-sufficiency rate. The consumption of grain is mostly rely on imports in Korea. To overcome the limit of the domestic seed market and increase maize self-sufficiency, the need to develop maze varieties for world-class is increasing at present through analyzing the market trend and prospect of the seed industry in South-eastern Asia.

• Journal of Plant Biotechnology
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• v.35 no.4
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• pp.245-256
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• 2008

The current legislation in South Korea clearly states that the tolerance threshold on the adventitious presence of GMO in environment-friendly agricultural products is 3.0% and no GM seed should be detected in their planting seed batches. To date, in Korea, there is no approved GM crop for commercial cultivation in field. However, several GM crops including rice, Chinese cabbage, potato and wild turf grass are currently under risk assessment for their environmental release. Also Korean government (Rural Development Administration, RDA) announced that 11 institutes including universities have been currently certified to carry out a risk assessment of GM crops. Meanwhile, the cultivated area and certified quantities of environment-friendly crops (organic, pesticide-free and low-pesticide) are sharply increasing every year according to the report of National Agricultural Products Quality Management Service (NAQS). In detail, in 2007, the certified quantities of environment-friendly agricultural products were elevated up to 100-fold for organic, 171-fold for pesticide-free and 2,324-fold for low-pesticide crops when compared with those in 1999. The total certified quantity of environment-friendly cereal crops in 2007 was equivalent to 6.4% of total production of cereal crops. Moreover, 24% of total production of root and tuber crops such as potato and sweet potato were certified for environment-friendly agricultural products. In these circumstances, I strongly suggest that current legislations on GM crop's safety management should be revised to include strategies for the coexistence of GM with non-GM crops, especially environment-friendly crops before GM crop is approved to be cultivated for commercialization. Since all types of crops are grown in an open environment, the adventitious presence of GM crops among non-GM crops is inevitable if appropriate measures for coexistence are not established for species by species such as isolation distance, workable management measures to minimize admixture.

• Korean Journal of Environmental Agriculture
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• v.19 no.4
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• pp.339-344
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• 2000

Utilization of animal excreta in aquaculture can have potentials of high fish production and low maintenance costs for fish farming and it can reduce water pollution caused by animal waste disposal. Integration of wastewater treatment pond system with aquaculture has been utilized in many countries. Ecologically balanced pond ecosystem is formed through the stabilization of wastes, the growth of aquatic plants, and the cultivation of fish. The most appropriate fish for rearing in these ponds are those which can feed directly on phytoplankton, especially algae. Carp were introduced into a tertiary pond - water depth of 2.2 m, water surface area of $130\;m^2$, volume of $148\;m^3$ - of a pond system treating milk cow excreta. The carp production was $125g{\cdot}m^{-2}year^{-1}$ which falls into upper range of $18\;-\;137g{\cdot}m^{-2}year^{-1}$ of treated sewage-fed carp farming of other countries. Average $BOD_5$ and T-N of the pond was 19.8 and $21.0\;mg{\cdot}L^{-1}$ respectively, and the ecological environment of it was suitable for growth of carp. Several carp of 100g were introduced in August into a secondary pond of the treatment system, whose average $BOD_5$ and T-N was 27.9 and $30.8\;mg{\cdot}L^{-1}$ respectively. They were died within one week, which may be attributed to the depletion of dissolved oxygen at dawn. Effluents from primary treatment can be used in fish pond with dilution and those from secondary treatment can be directly funnelled into it. Waste stabilization pond treating animal excreta can be utilized for fish rearing when its water quality maintains secondary treatment level.

• Korean Journal of Environmental Agriculture
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• v.33 no.4
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• pp.358-363
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• 2014

BACKGROUND: Many strawberry growers are utilizing daylength extension by using incandescent bulb or fluorescent lamp to break dormancy of strawberry induced by low temperature and short day conditions. Conventional incandescent bulb and fluorescent lamp consume a lot of electricity and have short longevity. Red light known for most efficient wavelength for daylength extension light of short-day plant and long-day plant. This study was conducted to verify the effects of red light to enhance growth and to increase production of strawberry (Fragaria ${\times}$ ananassa Duch. cvs. "Seolhyang") METHODS AND RESULTS: Three red light (660nm) of 0.70, 0.87, and $1.05{\mu}mol/m^2/s$ (PAR) and conventional incandescent bulb of 40 Lux were treated respectively under the pot experiment. All treatment irradiated from 18:00 to 24:00 for 6 hours. Red light treatment tend to increase leaf stem number, flower stem number, weight of flower stem, crown weight, root weight, and leaf area of strawberry then incandescent bulb treatment. In field experiment, red light of $0.7{\mu}mol/m^2/s$ (PAR) and conventional incandescent bulb of 40 Lux were irradiated respectively. Field experiment showed that the leaf number, leaf weight, and crown weight of strawberry increased than those of incandescent bulb control with red LED of $0.7{\mu}mol/m^2/s$ (PAR). Red LED treatment increased the fruit number over 15g than incandescent bulb. Furthermore, red LED treatment decreased fruit number below 15g of strawberry than incandescent bulb treatment. Therefore, We believed that red LED treatment increased marketable fruit number by increment of weight of each fruit. Consequently, marketable fruit number, fruit weight, and fruit production of strawberry were increased than those of incandescent bulb by 5 %, 2.9 %, and 8.5 % respectively, but not showed significantly differences. CONCLUSION: These results presumably due to directly enhanced photosynthesis of strawberry leaves and activated action of Pfr phytochrome form by red light. In conclusion, red LED of 660nm could be used for daylength extension light source to enhance production of strawberry.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.59 no.2
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• pp.144-150
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• 2014

Yams (Dioscorea spp), which are edible or medicinal tuber crops, are a important crop in South Korea. Yams require a high level of soil fertility. The various cultural practices such as fertilizing and plowing were tested for marketable tuber production in Chinese yam (Dioscorea opposita). Tuber yield was also affected by organic matters in soil. Application higher level of organic matters result in increased each tuber weight and tuber yield per unit area. The nutrient absorption quantity of the plant such as nitrogen, phosphoric acid, calcium and potassium was increased from 100~120 days after planting, which time to begin tuber enlargement. The tuber yield was increased when the fertilization increased in quantity. Total yield and marketable ratio were the highest in 31~32 kg/10a of nitrogen fertilizer. From above result, income become larger with increase of marketable yield and quality improvement at 63% (27 kg/10a) level of conventional N fertilization (43 kg/10a). The tuber yield was not significantly different between with in various application level of potash fertilizer. Tuber size and weight decreased accordingly to decreased fertilizing level, so the rates of small tubers increased greatly at cultivation without chemical fertilizer. In considering the accumulation rates of allantoin in Chinese yam tubers, the apt harvest season was after October. The allantoin quantity of it was not influenced with nitrogen fertilizing. Moreover it was advantageous with decrease of chemical fertilizer and appropriate fertilizing in soil environment protection. Commercial tuber's number and yield were increased in trenching before planting with trencher compared with rotavating with tractor.

• Journal of Sericultural and Entomological Science
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• v.9
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• pp.49-66
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• 1969

Eri-silkworm is known as a tropical insect where as poly-voltine type in that area. It eats caster oil plant leaves which are cultivated as an every year cultivatable seed oil use in this country, even though it grows for many years in tropical countries. That is why, farmers have freedom for its cultivation in any year if they want. Therefore, eri-silkworm rearing service is flexible for its diet procurment as wish of farmer. The eri-cocoon price or economical fluctuation may be reactable for the rearing work not like as mulberry cocoon. Fortunately, it also eats cynthia tree leaves. Standing from such a easy condition, the authors have studied about this problem since 1963 to develope a culturing method of eri-silkworm rearing in this country and the authors brought out the matters to be produced as an industry scale. Here, the authors summarized their works of the results covering with thirty three work tables. The obtained results are as follows.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.1
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• pp.92-98
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• 2010

Physicochemical properties, free sugar and volatile flavor compounds of citrons harvested in different cultivation areas, such as Geoje, Goseong, Goheung, and Namhae, were analyzed and compared. Total weight of citron, ranging from 107.97 g to 154.86 g, was significantly different according to producing area. Weight ratio of flesh to whole citron was higher than one of peel in citron produced from Geoje, Goheung-improved, or Namhae-native. Citron size was the highest in Namhae-native citron, but the color of peel was significantly the higher in Goheung-native and its improved citron. In the peel of citron, hardness of citron produced from Geoje was the strongest (2337.13 $cm/kg^2$) whereas citron produced from Goseong (1592.38 $cm/kg^2$) showed the softest hardness. Moisture content was 85.35~87.81 g/100 g and ash was contained below 0.8 g/100 g in flesh of all samples. Although crude fiber content in Geoje ctiron was significantly the lowest in the peel, peel was 1.88~2.60 times higher than flesh. The order of sugar content seemed to be fructose> glucose> sucrose in all citrons, and content of fructose or glucose was higher in peel than flesh. Content of total sugar was 8.44~12.19 g/100 g in citron, and contents of improved citrons from Goheung and Namhae were significantly higher than those of native citrons. In addition, major volatile compounds were dl-limonene (59.52~74.30%) and $\gamma$-terpinene (5.60~7.88%) among 15 kinds of volatile compounds identified from citron peel. These results suggested that physicochemical properties and volatile flavor compounds of citrons showed some differences with regard to producing areas.