• Proceedings of the Korean Society of Crop Science Conference
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• 2004.04a
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• pp.262-263
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• 2004

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.4
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• pp.336-343
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• 2019

Wet direct-seeding (WDS) is an important method for improving the competitiveness of rice production in South Korea. We analyzed the optimum direct-seeding date to establish the rice standing rate in each area and selected suitable areas for WHS by considering the heading stage limit date for improving cultivation safety. As a result, the rice direct-seeding date to control weedy rice was around 5.15, 5.17-5.19, and after 5.20 in southern Youngnam, southern Honam, and the Middle Coast areas, respectively. However, the optimum seeding date for good standing rice was in late March in most areas. Analyzing by area, most of the southern plains and parts of the central inland plain are suitable for WHS. However, most parts of Gwangwon-do, and the northern parts of Chungbuk, Gyeongbuk, and Yeonghonam areas are not suitable for WHS, and should therefore avoid WHS.

• Korean Journal of Plant Resources
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• v.27 no.4
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• pp.359-364
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• 2014

This text was experimented and investigated the optimum production time and germination characteristic of Fabaceae plant seed that collect in Korean Chungnam. Optimum time of seed production was early-mid October of Chamaecrista nomame, early November of Lespedeza cuneata and early-mid November of Lespedeza bicolor. Epiphytic amount of seed full ripe was the most times in early October of Chamaecrista nomame, early November of Lespedeza cuneata and Lespedeza bicolor, respectively. Seed rate of maturity was the highest times in early November of Chamaecrista nomame, mid November of Lespedeza cuneata and Lespedeza bicolor, respectively. Germination rate by seed collection time was the highest times in early October of Chamaecrista nomame (99.8%), mid November of Lespedeza cuneata (68.3%) and early November of Lespedeza bicolor (24.3%). Germination days by seed production time was the shortest times in mid October of Chamaecrista nomame, mid November of Lespedeza cuneata and Lespedeza bicolor, respectively. Optimum temperature of germination was $15{\sim}35^{\circ}C$ in Chamaecrista nomame, $25{\sim}30^{\circ}C$ in Lespedeza cuneata, and Lespedeza bicolor was difficult judgment of germination optimum temperature because of low germinating rate.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.3
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• pp.217-223
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• 1992

Cotton has been an important fiber crop in Korea for a long time. The objective of the study was to investigate the effects of planting and transplanting dates, transplanting density and fertilizer application rate on seed cotton and lint yields, and gross income for barley-cotton double cropping in southern part of Korea. Transplanting culture of upland cotton cultivar Mokpo 4 on June 10 to 20 produced 80 to 83% more in seed cotton yield and 79 to 82% more in lint yield compared with the yields of direct planted on June 10 just after harvesting naked-barley. Mokpo 4 was better than Suwon 17 and Paymaster for the transplanting culture after barley harvest in double cropping. Optimum fertilizer application rate was N 80-P$_2$O$_{5}$ 78-K$_2$O 106 kg /ha, and optimum transplanting density was 70$\times$20cm for the transplanting culture of upland cotton after barley in double cropping system. The highest total yields 5.03 to 5.09t /ha in barley-cotton double croppings were harvested in barley drill-seeding and cotton transplanting culture on June 10 to 20 compared with seed cotton yield 1.51t /ha of the cotton monoculture planted on May 1. Their gross income also was 40% more than that of the cotton monoculture, and 30% more than the cotton direct seeding just after barley harvest on June 10. Cotton intercropping between barley rows provided 2-11% more in gross income compared with cotton direct seeding after barley harvest on June 10. Of the cotton intercroppings between barley rows, cotton intercropping of one row between the barley rows of 60cm width provided 5 to 9% more in gross income than the other cotton intercroppings between barley rows.s.

• Journal of environmental and Sanitary engineering
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• v.13 no.2
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• pp.95-105
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• 1998

This research was investigated which denitrification of wastewater containing nitrate, using upflow anaerobic sludge blanket process. The upflow anaerobic sludge blanket process is also used for both artifical and industrial wastewater. Main ingredients investigated in the artifical and industrial wastewater experiment were the determination of optimum organism/nitrate ratios, nitrate removal efficiency by various hydrogen donor addition and characteristics of granular sludge and gas production in case of various hydrogen donor addition. From the experimental results the following conclusions were made: In case of adding methanol, ethanol and sodium acetate as hydrogen donor granular sludge was formed 50 days after seeding. Average diameter of granular sludge was 4.0 mm and settling velocity was 37 cm/min. Production rate of gas 3.3 L/d in case of adding methanol as hydrogen donor in wastewater containing 150mg/L nitrate. However adding ethanol and sodium acetate as hydrogen donor, gas production rate were 2.2-2.7L/d respectively. In case of adding methanol as hydrogen donor treatability of artifical wastewater contained 150mg/L as nitrate was about 93%. But in addition of sodium acetate in wastewater contained 40mg.L as nitrate, nitrate removal efficiency was 80%.

• Korean Journal of Weed Science
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• v.17 no.1
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• pp.124-134
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• 1997

As control of plant diseases, insects and weeds were heavily relied on pesticides, residues of pesticides in environment and food supply were recently focused by environmentalists and consumer groups. The reduction of pesticide use was implemented in Sweden, Denmark, Netherland, England, and United States. Therefore, it is very important to discuss environmentally sound systems of weed management including cultural, mechanical, and integrated weed control. Mechanical methods using tillage, cultivation, mulching, burning, mowing, solarization, and UHF are used as one of most effective environmentally sound weed management systems. Cultural practices favoring the crops are excellent weed management measures. Correct seedbed preparation for the soil and cultural system, and use competitive cultivars contribute to weed management. Increasing crop density by higher seeding rate or by narrowing row width and careful attention to optimum fertility to produce vigorous crop plants increase competitiveness of crops against weeds. Crop rotation breaks life cycles of weeds by alternating the crop it must associate with. Herbicides are efficient and profitable to control weeds, but must be part of a total weed management program with use of minimum rate. The best weed management will be an integrated approach including two or more methods to manage weed problems.

• Korean Journal of Plant Resources
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• v.31 no.1
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• pp.24-31
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• 2018

Amaranth (Amaranth caudatus) is attracting attention as a preference crop in Gyeongsangbuk-do province. To determine its growth potential and cultivation requirements, we investigated its growth characteristics, dry matter productivity, and grain yield according to the growing period. Growth and dry matter productivity were significantly higher for plants that were sown on May $10^{th}$ when the temperature was the highest, whereas the yield was significantly higher for plants that were sown on April $10^{th}$. Amaranth grain yield ranged from 96 to 243 kg according to the sowing date and cultivation year. The optimum harvest time for plants that were sown on April $10^{th}$, May $10^{th}$, and June $10^{th}$ were 120, 110, and 110 days after seeding, respectively. The mean temperature and growing period had a significant quadratic function with yield. Based on these equations, the optimum growing temperature was estimated as $20.6^{\circ}C$ and the optimum growing period as 104-119 days after seeding.

• Journal of Korean Society of Water and Wastewater
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• v.11 no.2
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• pp.112-127
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• 1997

The purpose of this study is to get optimum operating factors of Upflow Anaerobic Sludge Blanket (UASB) reactor by introducing methods that make it to reduce inhibition possible in each process wastewater treatment. The used substrates, concentrated corn starch liquid (CSL) wastewater, modified starch, filtering and decoloring wastewater, ion refining wastewater, and mixed wastewater including modified starch and not including modified starch, are generated from molasses process. The seeding sludge is the digested sludge that had been applied to molasses wastewater. Batch test to reduce the inhibition factors that might be existed in each wastewater was examined. Based on the this test, the optimum operating factors according to alkalinity and pH variation was studied through the continuous test using three 5.5 L UASB reactor. The first reactor added $NaHCO_3$ to control alkalinity. The hydraulic retention time (HRT) reduced to 8 hours and the organic loading rate increased gradually. The second reactor changed the pH of influent from 7.0 to 6.0 using NaOH. The third reactor was operated without changes to compare the above two reactors. As the result, the inhibition in concentrated CSL wastewater was removed by adding iron (II). When trace metals were added to mixed wastewater not including modified starch, the digestability by gas production rate increased to more fifty percentage than mixed wastewater that was not adding the trace metals. The reason that the inhibition did not decreased in spite of adding trace metals and nutrients was influenced by high concentration generated during the acid fermentation. The UASB reactors using the mixed wastewater with the most effective performance were operated as 500 mg/L as $CaCO_3$ alkalinity and 6.0 pH at steady state, and at this time, the gas production rates were 283 and 311mL gas/g $COD_{added}$. The COD removal rates were 84.7 and 86.3%, respectively.

• Korean Journal of Medicinal Crop Science
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• v.26 no.1
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• pp.64-71
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• 2018

Background: The cultivation of ginseng (Panax ginseng C. A. Meyer) in greenhouses could reduce the use of pesticides and result in higher yield; however, construction costs are problematic. The adaptation of direct-sowing culture in greenhouses could reduce the cost of ginseng production. Methods and Results: To improve seedling establishment in direct-sowing culture, effects of sowing density (SD), number of seeds sown per hole (SN), and thinning (TH) treatment on the root yield were investigated after 3 years of seeding. The emergence rate was significantly influenced by SD, but not by SN or TH. Damping-off and rusty roots increased with an increase in SN with diminishing effects of SN on seedling establishment. Root weight and diameter were affected by SD, SN, and TH, however, there were no statistical significances. The total number of roots harvested per unit area increased with increasing SD and SN, and the weight of roots was affected by SD, but not by SN or TH. Conclusions: Multi-seed sowing per hole and/or thinning might not be an efficient method for the direct-sowing culture of ginseng. The SD for direct seeding culture in greenhouses should be approximately $33-42seeds/m^2$ for an optimum yield of 3-year-old ginseng.

• Korean Journal of Plant Resources
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• v.15 no.1
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• pp.67-71
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• 2002

In order to determine the optimum level of three major fertilizers for Saururus chinensis, we applied to the soil at a rate of N(0, 4, 7, 10kg/10a), P$_2$O$\_$5/(0, 1.5, 3, 4.5kg/10a) and K$_2$O(0, 3, 6, 9kg/10a) prior to seeding. Regarding physical properties after the application, the values of pH, OM, Mg, CEC and EC were higher than those of the pre-application, but the contents of P$_2$O$\_$5/, K and Ca were lower. With application of three major fertilizers, dry weight of leaves per 10a was 26∼108kg greater than that of control(281kg) and dry weight of root tuber was higher by 19∼157kg than that of control(610kg). In regression equation of fertilizer recommendation for two-year-old Saururus chinensis, the optimum level of N-P$\_$2/O$\_$5/-K$\_$2/O fertilizer was determined by 7.1, 2.5, 4.2kg/10a, respectively.