• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.830-835
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• 2011

Total soil microbial activities have great impact to soil management for organic farming. This study was evaluated in the soil microbial community by fatty acid methyl ester (FAME) in a controlled horticultural field for strawberry organic farm. Experimental plots were prepared with a high level of soil electrical conductivity (EC) and a optimum level of soil EC. Soil microbial biomasses and communities of total bacteria, Gram-negative bacteria, Gram-positive bacteria, actinomycetes, fungi, and arbuscular mycorrhizal fungi in the high level of soil EC were significantly larger than those in the optimum level of soil EC. Lower ratios of cy17:0 to 16:$1{\omega}7c$ and cy19:0 to 18:$1{\omega}7c$ were found in the optimum level of soil EC than those in the high level of soil EC, indicating that microbial stress decreased.

• Korean Journal of Food Science and Technology
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• v.14 no.1
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• pp.49-56
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• 1982

The effects of measurement conditions on the emulsifying capacity(EC) and emulsion stability(ES) of proteins were studied in order to develop laboratory standard methods for the evaluation of emulsifying properties. The EC of proteins decreased with the increments of protein concentration and mixing rate. It increased with the increasing oil addition rate up to 0.8 ml/sec, but did not change at $0.8{\sim}1.2\;ml/sec$. The addition of sodiumchloride enhanced EC of proteins, attaining to the highest EC at 0.3M NaCl for Pro-Fam and 0.1M NaCl for Na-caseinate. The ES of Pro-Fam was higher than that of caseinate. The ES was increased by the increments of protein concentration, oil addition volume, mixing rate and mixing time. The EC and ES showed a close relation to the NSI of proteins, reaching to the lowest values of EC and ES at the isoelectric regions of proteins. The laboratory methods for measurements of emulsifying properties of proteins were established. The emulsifying properties of a laboratory-made soybean protein isolate were compared to those of commercial products by using the methods.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2020.08a
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• pp.54-54
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• 2020

배추는 근본적으로 저온성 작물로 고온에 견디는 힘이 약할 뿐 아니라 가뭄이나 다습에도 취약하다. 그런데 2007년 이 후 매년 봄·초여름 가뭄이 지속되고 있으며, 예전처럼 강우에 의한 피해보다는 빈번히 나타나는 고온, 가뭄, 폭염 등 이상기상 환경조건에서 병 발생 및 생장지연으로 고랭지배추의 안정 생산이 위협받고 있다. 가뭄이 매년 지속됨에 따라 고랭지배추 재배지에서도 관수의 필요성이 인식되면서 관수를 실시하고 있으며, 대부분 스프링클러로 관수하고, 분수호스나 점적호스도 일부 이용하고 있으나 아직 토양수분, 토성이나 작물상태, 재배시기 등 환경요인을 고려한 과학적인 수분관리가 이루어지지 못하고 있어 고품질 안정생산을 위해서는 수분관리의 과학화가 필요한 실정이다. 관비재배는 적정한 비료를 필요한 위치에 공급하는 방식으로 비료의 효율을 높이면서 환경오염을 최소화하고, 비료과다 시용에 따른 환경오염 등을 회피할 수 있는 좋은 수단이다. 본 연구는 앞으로 고랭지배추 점적관수재배시 가뭄 극복과 효율적인 시비를 위한 적정 관비농도를 구명하고자 하였다. 배추품종은 수호를 이용하였으며 관비 EC농도(dS/m)는 0.4, 0.6, 0.8, 1.0, 1.2, 1.4 등 6처리를 두었으며 기준시비량은 N-P-K=32.0-7.8-19.8kg/10a로 하였다. 시험은 고령지농업연구소내 유리온실에서 4월 상순부터 5월 하순까지 직경 20cm 사각화분에 정식하여 재배하였다. 관비는 정식후 15일부터 7일 간격으로 5회 주었으며 관비량은 1회 화분당 65ml를 주었다. 화분은 완전임의배치 3반복으로 배치하였다. 초장은 정식후 38일까지 컸으며 엽장은 정식후 52일까지도 크는 경향을 보였다. 엽폭은 정식후 45일에 가장 많이 컸다. 초장, 엽장, 엽폭 모두 관비농도가 높을수록 커지는 경향이었으며 EC농도(dS/m) 1.4에서 가장 높게 나타났다. 주당 엽수와 주중도 EC농도가 높아질수록 많아졌으며 EC농도 1.4 처리에서 가장 많았고 그 다음이 EC 1.2 처리였다. 그러므로 관비 농도는 EC 1.4 dS/m 로 주는 것이 배추 생육에 좋을 것으로 생각된다.

• Journal of Bio-Environment Control
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• v.21 no.4
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• pp.305-311
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• 2012

To investigate the influence electrical conductivity (EC) of nutrient solution and light intensity on growth of red leafy lettuce, fresh and dry weights, number of leave, chlorophyll concentration and production efficiency were evaluated through nutrient film technique system. The levels of EC were 0.5, 1.0, 1.5, 2.0, 3.0, and $6.0dS{\cdot}m^{-1}$, and those of light intensity were 120, 150, and $180{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. Under photoperiod of 16 h/day, the temperature was maintained in the range of $20{\sim}25^{\circ}C$. Planting density was $10{\times}10cm$ (100 plants/$m^2$). When red leafy lettuce were grown in the EC range of $0.5{\sim}1.5dS{\cdot}m^{-1}$, the fresh and dry weights decreased as the EC levels and light intensity were lowered, however, Hunter's a value showed no significant differences among the treatments of EC and light intensity levels (Ex. 1). The fresh and dry weights and production efficiency ($g{\cdot}FW/kw$) were the highest in the treatment of $3.0dS{\cdot}m^{-1}$ and $180{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ when crops were grown under the EC range of EC $1.5{\sim}6.0dS{\cdot}m^{-1}$ (Ex. 2). But the fresh and dry weights, number of leaves, and production efficiency of $2.0dS{\cdot}m^{-1}$ were the highest when the light intensity was $180{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ (Ex. 3). The SPAD value increased gradually as EC levels were elevated. From the above results, we concluded that optimum levels of EC and light intensity were $2.0dS{\cdot}m^{-1}$ and $180{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, respectively, for production as well as production efficiency of red leaf lettuce in plant factory.

• Journal of Practical Agriculture & Fisheries Research
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• v.24 no.4
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• pp.5-10
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• 2022

After ginseng seeds were planted in sand, the first experiment was conducted by germinating seeds with a nutrient concentration of 0 to 2.5. The average germination rate was highest in EC 1.0 with a nutrient concentration of 87%, followed by the comparative group with EC 1.5, 82%, EC 2.0, 78%, EC 2.5, 72%, EC 0.5, 71%, and con, 68%. Ginseng seeds were sown in the sandy soil, grown for 60 days were transferred to the ginseng soil, and the second growth experiment was conducted 30 days later. As a result of the experiment, at the nutrient concentration of EC 1.5, it grew from 11.64cm to 15.54cm, the average total length(cm)increased the most from 3.90cm. At the EC 1.0, nutrient concentration, the average total weight(g)increased the most from 0.42g to 0.75g to 0.33g. At the EC 0.5, nutrient concentration, the average total root width(mm) increased the most from 4.06mm to 5.52mm to 1.46mm.

• Horticultural Science & Technology
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• v.28 no.6
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• pp.973-979
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• 2010

The objective of this study was to determine the effect of electrical conductivity (EC) of nutrient solution on the growth, nutrient uptake of potted kalanchoe plants ($Kalanchoe$ $blossfeldiana$ 'New Alter') and the nutrient accumulation at the growing media with growth stage in ebb and flow subirrigation systems. Significant differences in leaf area, plant height, and dry weight of the plants were found among the different ECs of nutrient solution of 0.8, 1.6, 2.4, and $3.2dS{\cdot}m^{-1}$. Particularly the difference in plant growth became significantly greater from 5 weeks after treatment. The overall growth was the highest at EC $1.6dS{\cdot}m^{-1}$. Leaf area, plant height, and dry weight were maintained higher when EC increased to $2.4dS{\cdot}m^{-1}$, but rapidly decreased after EC $3.2dS{\cdot}m^{-1}$. The uptake of NO3-N was the greatest while that of $Mg^{2+}$ was the lowest at EC $1.6dS{\cdot}m^{-1}$, even though small differences were found among macro elements. The EC at the top layer of the growing media was 1 to 3 times higher than that at the bottom layer. Nutrient accumulation was accelerated in both the top and bottom layers with growth stage. At EC $3.2dS{\cdot}m^{-1}$, the growth of the plants was suppressed due to higher nutrient accumulation at the growing media. From the results, the strength and composition of nutrient solution should be determined by considering nutrient accumulation at the growing media in addition to EC of nutrient solution in ebb and flow subirrigation systems.

• Journal of agriculture & life science
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• v.53 no.1
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• pp.13-21
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• 2019

This study was carried out to acquire basic data for a long-term hydroponic culture through investigating water and inorganic ion uptake characteristics at different EC level of nutrient solution of three tomato varieties. Three different tomato varieties, the European type(cv. Daphnis), the Asian type(cv. Super Doterang) and cherry type(cv. Minichal), were used for the investigation. Also, the deep flow technique(DFT) was applied. The three different electrical conductivity(EC) level(1.0, 2.0, 3.0, and 4.0 dS·m-1) of hydroponic nutrient solution were used as variable. At a high EC level of nutrient solution, the leaf area and fresh weight decreased in the early stage, and its growth(plant height, leaf number, leaf area, fresh-weight) was poor with salt stress. Result showed that the higher the EC level of the nutrient solution, the lesser was water uptake. The water uptake was not significantly different from varieties in the first survey, but In the second survey, the 'Daphnis' did not show a significant decrease in water uptake in the EC level higher than 2.0 dS·m-1., on the other hand, 'Super Doterang' presented very low water uptake. At a low EC level, N, P, and K, were absorbed more than the concentration of the irrigation water, while Ca, Mg, S uptake were low. At a high EC level, almost ions absorbed less than 50% of the initial concentration of irrigation water. Thus, imbalance among ions was severe at low EC level compared to high EC level. 'Daphnis' was a variety that effectively utilize nutrients under nutrient stress, showing high absorption at low concentration condition and low absorption at high concentration condition. However, 'Daphnis' suffered most seriously by absorbing nutrients excessively.

• Korean Journal of Environmental Agriculture
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• v.25 no.1
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• pp.64-70
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• 2006

This study was conducted to investigate the concentration of fertigation for optimum yield and soil management of tomato cultivation in soils with different Electrical conductivity (EC) level under PE film house. The EC levels of soil were adjusted to 1.4, 3.0 and 5.4 dS/m and fertigation concentrations were supplied with 0.0 (groundwater), 1.0, 2.0 and 3.0 dS/m, respectively. When the concentration of fertigation was supplied over 3.0 dS/m to soil with EC 1.4 dS/m, the concentrations of $NO_3-N,\;avail.-P_2O_5$, and exchangeable K in soil were increased after the experiment. When fertigation concentration was supplied over 2.0 and 1.0 ds/m to soil with EC 3.0 and 5.4 dS/m respectively, the nutrient were also accumulated in the soil. Thus, the optimum concentrations of fertigation for optimum yield and soil management for tomato cultivation were recommended $1.0{\sim}2.0dS/m$, 1.0 dS/m and ground water (0.0 dS/m) to soils with EC 1.4, 3.0 and 5.4 dS/m, respectively. The fruit weight marketability and marketable yield of tomato were not significant among the treatments at 5% level by LSD. The concentrations of T-N, $P_2O_5\;and\;K_2O$ in tomato leaf were increased with increasing of fertigation concentration whereas the concentrations of CaO and MgO decreased with increasing of fertigation concentration.

• Weed & Turfgrass Science
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• v.1 no.4
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• pp.69-75
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• 2012

In response of fungicides for control of gray snow mold, isolates of Typhula incarnata were collected from three golf courses in 2012 Yongpyeong, Korea and tested for sensitivity to propiconazole, tebuconazole and azoxystrobin fungicides. Four discriminatory concentrations were used to detect in vitro sensitivity of 50 isolates. Mean 50% effective concentration inhibiting mycelial growth ($EC_{50}$) values for tebuconazole was the lowest among the three fungicides. The $EC_{50}$ value of tebuconazole ranged from 0.0005 ${\mu}g\;ml^{-1}$ to 0.014 ${\mu}g\;ml^{-1}$ with a mean of 0.0048 ${\mu}g\;ml^{-1}$. The mean $EC_{50}$ values of propiconazole in triazole family was 0.5825 (0.78-1.651) ${\mu}g\;ml^{-1}$. $EC_{50}$ value of azoxystrobin ranged from 0.0017 ${\mu}g\;ml^{-1}$ to 0.131 ${\mu}g\;ml^{-1}$ with a mean of 0.0278 ${\mu}g\;ml^{-1}$. There was no correlation among $EC_{50}$ values for propiconazole, azoxystrobin and tebuconazole indicating no cross-resistance relationships with each other. Results of this study were confirmed no resistance isolates in vitro sensitivity of T. incarnata of three fungicides in Yongpyeong.

• Journal of Bio-Environment Control
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• v.14 no.4
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• pp.245-253
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• 2005

This study was carried out to determine the optimum EC supply by accumulation amount of solar radiation in closed system. EC concentration of drainage was higher than that of supply. The higher EC concentration of supply was, the lower pH of drainage was. It was no difference in the quality of cut rose 'Nobles' (Rosa hybrida), stem length, stem diameter, leaf number, petal length, and petal diameter by EC treatment by season. The yield was higher about $6\%$ in treatment of EC $1.3dS{\cdot}m^{-1}$ in April and May, about $10\%$ in treatment of EC $10dS{\cdot}m^{-1}$ in June, July and August, and about $10\%$ in treatment of EC 1.0 or $1.3dS{\cdot}m^{-1}$ in September and October than the others. In general, the yield of the cut rose was higher in treatment of (B) EC 1.3 mS/cm in spring, EC $1.0dS{\cdot}m^{-1}$ in summer, EC $1.3dS{\cdot}m^{-1}$ in autumn, and EC$1.6dS{\cdot}m^{-1}$ in winter.