• Journal of Applied Biological Chemistry
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• v.63 no.4
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• pp.347-355
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• 2020

Several sensors have been developed for soil and plants to assess plant stress due to climate change. Therefore, the objective of the study is to nondestructively evaluate temperature stress on plant by monitoring climatic and soil conditions and plant responses using various sensors. Plant responses were monitored by electrical conductivity in plant stem and sap flow rate. Electrical conductivity in plant stem reflects the physiological activity of plants including water and ion transport. Fully grown Brassica oleracea var. italica was exposed to 20/15 ℃ (day/night) with 16 h photoperiods as a control, low temperature 15/10 ℃, and high temperature 35/30 ℃ while climatic, soil, and plant conditions were monitored. Electrical conductivity in plant stem and sap flow rate increased during the day and decreased at night. Under low temperature stress, electrical conductivity in plant stem of Brassica oleracea var. italica was lower than control while under high temperature stress, it was higher than control indicating that water and ion transport was affected. However, chlorophyll a and b increased in leaves subjected to low temperature stress and there was no significant difference between high temperature stressed leaves and control. Free proline contents in the leaves did not increase under low temperature stress, but increased under high temperature stress. Proline synthesis in plant is a defense mechanism under environmental stress. Therefore, Brassica oleracea var. Italica appears to be more susceptible to high temperature stress than low temperature.

• Korean Journal of Ecology and Environment
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• v.36 no.2 s.103
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• pp.191-199
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• 2003

This study was conducted to investigate a seasonal variation of phytoplankton communities at 6 stations in the Hantan River from November, 2001 to August, 2002. Electric conductivity gradually increased from the upper reaches to the down reaches. DO differed not much from the upper reaches to down reaches, but it decreased at the station where the pollutants inflowed. T-N and T-P concentrations were high at station 4${\sim}$6. Chlorophyll-a concentration gradually increased at the mid and down reaches. It was high in May but decreased in August by the heavy rains. Phytoplankton communities were identified a total 354 taxa composed of 99 genus, 320species, 19 varieties, 3 forma and 12 unidentified species. There were 135 taxa of Chlorophyceae, 134 taxa of Bacillariophyceae, and the other taxa were Euglenophyceae, Cyanophyceae, Xanthophycaea, Chrysophyceae and Dinophyceae. Standing crops ranged from 8,600 to 337,100 cells/mL and it was lower in August than May by the rains. Dominant species included Achnanthes alteragracillima, Achnanthes convergens, Achnanthes minutissima and Cymbella minuta var. silesiaca which were the saproxenous species at the reaches, and were Cyclotella meneghiniana, Chlamydomonas pseudopertyi and Nitzschia which were saprophilous and eutrophic species at the down reaches. The correlation coefficients between phytoplankton standing crops and EC, BOD and T-N, T-P was 0.68, 0.60, 0.60 and 0.70, respectively. All correlation coefficients between Chlorophyceae and EC, BOD and T-P were higher than 0.6. A. convergens were negative correlations with EC and BOD, but N. palea were positive with EC, BOD, T-N and T-P.

• Journal of the Korean Geotechnical Society
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• v.39 no.8
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• pp.41-48
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• 2023

Microbially induced calcite precipitation(MICP) is a novel cementation method meant to enhance soil engineering properties through the use of microorganisms. This study investigates the effect of different MICP concentrations on plant growth. Tall fescue seeds are grown in plant columns filled with Jumunjin sand. Following plant growth, the soil samples are treated with MICP via spraying method. The results indicate that the MICP-treated plants exhibit hampered growth compared with the untreated plants. pH and electrical conductivity(EC) tests are performed to analyze the changes in soil properties by MICP. The MICP-treated soils exhibit a pH = 7, similar to the untreated soil. However, the EC dramatically increases with the increase in the MICP concentration, which leads to an increase in the osmotic pressure of the soil surrounding the plant roots. Eventually, the higher osmotic pressure in MICP-treated soil hinders the absorption of water and nutrients in plant roots, thus inhibiting plant growth.

• Journal of Bio-Environment Control
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• v.2 no.2
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• pp.147-149
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• 1993

양액재배에 있어서 배양액 중에 있는 질소, 칼륨, 인, 칼슘, 마그네슘 등 식물 영양성분의 함유량을 항상 알맞게 유지시키는 일은 매우 중요하다. 아울러, 양액의 산도(pH)와 용존산소량(dissolved oxygen;DO)도 식물 생장에 큰 영향을 미치기 때문에 적절히 유지하지 않으면 안된다. 양액의 상태를 항상 작물 생육에 알맞게 유시키기 위해서는 먼저 양액의 조성과 관계가 있는 물리량을 정확히 측정할 필요가 있다. 특히 양액관리를 자동화하기 위해서는 정확도와 함께 신속하고도 간편한 측정방법이 필요하다. 양액 상태에 관한 주요 측정항목에는 전기전도도(electric conductivity : EC), 산도(pH), 용존산소량(DO)이 있다.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2010.10a
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• pp.23-23
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• 2010

전북 서해안 새만금 지역에 조성되는 간척지 면적 28,300ha의 30%인 8,400ha 정도가 농업용지로 사용되는 계획이 확정됨에 따라 해당 용지를 효율적으로 사용 할 수 있는 다양한 활용 방안이 요구되고 있다. 대단위 농업지구가 들어설 예정지인 새만금 광활 간척지는 네덜란드와 유사하게 토양의 대부분이 미사질 양토로 이루어져있어 적용 가능한 화훼류를 적절히 선발하고 적합한 재배기술을 도입한다면 대규모 화훼제배 단지로서의 성장 가능성이 충분할 것으로 판단된다. 따라서 전북 농업기술원에서는 2004년부터 7년에 걸쳐 새만금 간척지의 농업적 활용도 제고와 경관농업 육성을 통한 관광자원화 가능성을 확인하기 위하여 72종의 원예작물 적응시험을 실시하였으며 22종의 자생식물과 튤립, 아이리스, 수선화, 히아신스, 참나리 등 5종의 구근 화훼류를 적합 화훼류로 선발하였다. '08~09년에는 내염성과 저온 및 풍해 저항성이 있는 아펠톤, 골든아펠톤, 네그리타, 프랑소와즈, 키스네리스 등을 간척지적용 가능 주요 튤립 품종으로 선발 하였는데 선발된 품종들을 대상으로 높은 염농도 하에서의 체내축적 무기성분을 조사한 결과, K와 Mg은 증가되는 경향이었으나 Ca은 감소되었으며, Cl이온은 현저하게 증가하였다. 또한 튤립체내의 산도 및 전기전도도와 항산화효소의 활성이 증가하였는데 스트레스 반응결과 유해산소가 체내에 축적되고, 이를 중화시키기 위하여 수소이온을 소모함으로써 체내의 산도는 상승된 것으로 추정되며 염분함량이 높을수록 삼투압에 의하여 뿌리에서 흡수는 양분이 적은 반면 잎 줄기의 증산작용은 동일하기 때문에 상대적으로 체내의 농도가 높아져 전기전도도가 상승된 것으로 판단된다. 식물 스트레스의 지표물질로 사용되고 있는 proline 함량도 토양내의 염도가 상승되면서 증가되었으며 엽록소 함량은 감소되는 경향을 보였다.

• Korean Journal of Ecology and Environment
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• v.50 no.1
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• pp.148-156
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• 2017

In this study, we analyzed the relationship between phytoplankton community and physicochemical factors in 12 lakes located in Jeollanam-do based on the data surveyed from March to November 2014. Totally, 297 species of phytoplankton were identified including 98 Bacillariophyceae, 148 Chlorophyceae, 23 Cyanophyceae and 28 other phytoplankton taxa. The standing crops ranged from 124 to $59,148cells\;mL^{-1}$ and showed the highest in August with the increase of Cyanophycean cells. The self-organizing map (SOM) was optimized into $9{\times}6$ grid and was classified into 5 clusters based on the similarity of environmental factors and phytoplankton indices. The SOM results showed that phytoplankton communities had positive relationship with water temperature, SS, DO, BOD, TP and Chl-a, whereas low relationship with pH, TN, $NH_3-N$, $NO_3-N$, $PO_4-P$ and Conductivity. In Pearson's correlation coefficient, relationship between environmental factors and phytoplankton communities showed similar results with SOM.

• Journal of Bio-Environment Control
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• v.32 no.4
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• pp.328-335
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• 2023

For appropriate nutrient management and enhanced plant growth, soil sensors which reflect soil nutrient levels are required. Because there is no available sensor for nutrient monitoring, electrical conductivity (EC) sensor can be used to evaluate soil nutrient levels. Soil nutrient management using EC sensors would be possible by understanding the relationship between sensor EC values and soil temperature, moisture, and nutrient content. However, the relationship between soil sensor EC values and plant available nutrients was not investigated. Therefore, the objectives of the study were to evaluate effect of different amount of urea on soil EC monitored by sensors during pepper and broccoli cultivation and to predict the plant available nutrient contents in soil. During the cultivation period, soil was collected periodically for analyzing pH and EC, and the available nutrient contents. The sensor EC value increased as the moisture content increased, and low fertilizer treated soil showed the lowest EC value. Principal component analysis was performed to determine the relationship between sensor EC and available nutrients in soil. Sensor EC showed a strong positive correlation with nitrate nitrogen and available Ca. In addition, sum of available nutrients such as Ca, Mg, K, P, S and N was positively related to the sensor EC values. Therefore, EC sensors in open field can be used to predict plant available nutrient levels for proper management of the soil.

• Journal of Korean Society of Forest Science
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• v.102 no.3
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• pp.323-330
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• 2013

This study was conducted to know the effect of major physical-chemical characteristics of soil to be in the area of indigenous and naturalized plant in the sand dune of the western coastal area of Korea. The study was performed on the sand dunes distributed across Taean-gun and Buan-gun and the study period was from April to October in 2010. Sixty nine of $5m{\times}5m$ study plots were installed and the distribution of plants were investigated. We measured the soil characteristics including soil pH, organic matter, total nitrogen, available $P_2O_5$, soil cation exchange capacity, exchangeable cation, EC and NaCl. As a result, soil texture was classified as sand, in case of average pH, NaCl, and EC of soil to be in the area of indigenous herbaceous plant were 7.77, 0.03% and $0.52ds.m^{-1}$, indigenous woody plant of the mean pH, NaCl and EC were 7.31, 0.01%, $0.23ds.m^{-1}$. In case of naturalized herbaceous plant of the mean soil pH, NaCl and EC were 7.12, 0.01%, $0.29ds.m^{-1}$, naturalized woody plant of the mean soil pH, NaCl and EC were 7.34, 0.01%, $0.20ds.m^{-1}$ respectively. On average, naturalize plants showed in low salinity concentration than indigenous plants.

• The Korean Journal of Ecology
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• v.23 no.1
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• pp.45-49
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• 2000

Tolerances of aquatic plants (emergent plants) of cattail (Typha orientalis), water oats (Zizania latifolia), reed (Phragmites communis), and bulrush (Scirpus nipponicus) to salts and high NH₄/sup ＋/-N cone. of industrial wastewater were evaluated. Evapotranspiration of cattail and water oats plants was not affected when the wastewater containing 130 ppm NH₄/sup ＋/-N with electrical conductivity of 3.0 dS/m was supplied for 5 months. Shoot and root dry wt. of cattail and water oats were rather increased by irrigation of the wastewater while the biomass production of bulrush was greatly reduced. Storage nitrogen concentration in tissues of water oats and reed plants were higher than those in cattail and bulrush. Thus, water oats and reed plants were found to be the better aquatic plants to use in constructed wetlands for treating industrial wastewater of high salt and NH₄/sup ＋/-N.

• Korean Journal of Organic Agriculture
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• v.28 no.3
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• pp.417-430
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• 2020

Drought stress is one of major environmental stresses in plants; this leads to reduce plant growth and crop yield. In this study, we selected fungal isolate for mitigating drought stress in pepper plants. To do this, 41 fungi were isolated from rhizosphere or bulk soils of various plants in Jeju, Gangneung, Hampyeong in Korea. Out of 41 isolates, we screened two isolates without phytotoxicity through seed germination of tomato, pepper, and cabbage treated with fungal spores; through following plant assay, we selected GL02 as a candidate for alleviating drought stress in pepper plants. As a result of greenhouse test of pepper plants in drought condition, the stomatal conductance on leaves of pepper plants treated with GL02 was increased, whereras the malondialdehyde (MDA) and electrolyte leakage were decreased compared to that in control plants. When stressed plants were rewatered, stomatal conductance of the plants treated with GL02 was increased; the electrolyte leakage was decreased. Based on internal transcribed spacer (ITS) sequencing analysis, isolate GL02 was belonging to genus Trichoderma. Taken together, drought stress in pepper plants treated with GL02 was alleviated, when it was rewatered after drought-stressed, the plants could be recovered effectively. Therefore, Trichoderma sp. GL02 could be used as a bio-fertilizer to alleviate drought stress in pepper plants.