• Journal of Ginseng Research
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• v.28 no.4
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• pp.183-190
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• 2004

On May of 2002, the 34 isolates of Rhizoctonia solani were isolated from the symptom of damping-off on basal stems of 2-year-old to 6-year-old Panax ginseng which were cultivated in the 17 fields in Kyunggi-do, Chun­gcheungnam-do and Jeollabuk-do province in Korea. All isolates were identified as anastomosis group 2-1. Pre-emer­gence damping-off occurred on underground part of stem of 2-year-old ginseng in the pot trial with artificial inoculation. However, in the 4-year-old ginseng field with artificial inoculation, post-emergence damping-off occurred. The severe incidence of damping-off was found in the 6-year-old ginseng field in Kimje-si, Jeollabuk-do province on June 5 of 2003, the rate of which showed $18.6{\%}$ of area in the field by spread of the disease since 2-year-old. The sclerotia of R. solani, started to be formed after 7 days incubation on potato dextrose agar at $25^{\circ}C,$ were grayish brown, spherical to irregular and about $500{\mu}m$ in diameter, which became dark brown after 14 days incubation. The temperature range for the myce­lial growth of R. solani isolates was $5\~30^{\circ}C,$ and the optimal temperature was $25^{\circ}C,$ their growth were very poor at $5\;or\;30^{\circ}C$. The isolates grew at the range of pH $4.5\~8.1$ tested and optimal pH for growth was pH 4.5$\~5.8%, whereas their growth were very poor above the pH 7.2.

• Korean Journal of Weed Science
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• v.12 no.1
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• pp.8-15
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• 1992

Arrowhead (Sagittaria trifolia L.), a perennial weed dominant in paddy field, is considerably difficult to control by herbicides. The investigation on the effects of environmental factors on emergence of arrowhead tuber can aid for controlling this weed. The results exmined were as follows : From the results of emergence characteristics at different levels of temperature, arrowhead tuber could germinated at 15$^{\circ}C$-40$^{\circ}C$. The optimal temperature for basal emergence was ranged from 25 to 30$^{\circ}C$. Basal emergence at 15$^{\circ}C$ and 20$^{\circ}C$ began at 56 and 12 days after tuber plantation, respectively and were later than those at the optimal temperature. At the different levels of shading, all the tested tubers could emerged. The days required for basal emergence at 25% and 50% shading plots were shorter than those at 70%, 80% and non-shading plots. The basal emergence was more effective under blue and clear films than any other phyto-selective materials. Some of arrowhead tubers could not emerged under green, red and yellow films. On the soil pH, the basal emergence was best at soil pH 6.0 and 7.0. At soil pH 4.0, 5.0 and 8.0, the required days for emergence were longer than those at soil pH 6.0 and 7.0 and some of tubers could not emerged. Arrowhead tubers more then 0.5 g showed the shorter shooting days than those less than 0.5 g. Tubers were able to emerge at water depth ranging from 0 to 20 cm. At 3 cm and 5 cm water depth, the required days for basal shooting were shorter than those at any other levels of water depth. The emergence of basals was best at molding depth of 0 cm, and the rates at 3 to 5 cm of plantation depth were decreased. At 10 cm plantation depth, the shooting rate was significantly decreased.

• Korean Journal of Weed Science
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• v.17 no.1
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• pp.31-43
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• 1997

This study was carried out to investigate classfication of weedy rice (Oryza sativa) based on isozymes esterase and peroxidase, growth and developmental difference of weedy rices and rices grown under dry and water condition, and weedy rice control and tolerant difference of weedy rices in various herbicides using weedy rices collected from thirteen strains of Chonnam, one Chonbuk, two Kyeongki and two rice cultivars. 1. The collected weedy rices were classified into three groups based on isozyme esterase and peroxidase using polyacrylamide gel electrophoresis(PAGE) method. The classified groups were not same each other. 2. Plant height was taller in collected weedy rices than rice cultivars at 18 days after seeding under dry and water conditions, but number of leaves, shoot fresh weight, root fresh weight and root length were not significantly different between collected weedy rices and rice cultivars. In addition, growths of collected weedy rices were greater in dry- than water-condition. 3. After thiobencarb(S-4-chlorobenzyl diethythiocarbamate), molinate(S-ethyl hexahydro-1H-azepine-1-carbothioate) and oxadiazon(5-tert-butyl-3(2,4-dichloro-5-isopropoxyphenyl)-1,3,4-oxadiazol-2-one) were applied at 6 days before seeding, the weedy rices controlled 100% by thiobencarb at 2.1kg ai/ha and 024kg ai/ha oxadiazon treatment but controlled 26% to 67% by molinate at 6.5kg ai/ha. Rice due to the herbicides was injured severely(25% to 100%) in flood condition at time of rice seeding after oxadiazon at 0.48kg ai/ha and 2.1kg ai/ha thiobencarb application, except for molinate which injured rice slightly(4% to 13%) in drain condition. The collected weedy rices to all experimented herbicides showed slight intraspecific variations. The intraspecific variations of weedy rices decreased in the order of thiobencarb>molinate>oxadiazon.

• Journal of Soil and Groundwater Environment
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• v.13 no.4
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• pp.30-39
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• 2008

The uranium removal efficiency of rhizofiltration was investigated in lab scale experiment. Three plants such as sunflower (Helianthus annuus L.), bean (Phaseolus vulgaris var.), and Indian mustard (Brassica juncea (L.) Czern.) were cultivated in artificially contaminated solution by uranium at 30 ${\mu}g$/L and 80 ${\mu}g$/L for 72 hours. The removal efficiencies of three cultivars were calculated from the ICP/MS analysis of uranium mass in solution and the plant. For Helianthus annuus L., more than 80% of initial uranium were removed from the solution and the uranium concentration of residual solution maintained lower than 10 ${\mu}g$/L. For Phaseolus vulgaris var. and Brassica juncea (L.) Czern., their uranium removal efficiencies ranged from 60 to 80%. Even the uranium concentration of solution was higher than 500 ${\mu}g$/L, these cultivars removed more than 70% of initial uranium by rhizofiltration, suggesting that the rhizofiltration has a great capability to remove uranium in the contaminated groundwater. The removal efficiency of rhizofiltration by using Brassica juncea (L.) Czern decreased from 83% to 42% with the increase of pH in solution. From the results of the analysis for the uranium accumulation in plants, 99% of uranium transferred into the plant from solution were accumulated in the root and only 1% of uranium existed in the shoot part (including leaves), suggesting that the cost and the time to treat massive grown plants after the rhizofiltration could be dramatically cut down because only their root parts needs to be treated. Finally, the genuine groundwater having high uranium concentration (81.4 ${\mu}g$/L), sampled from Daejoun area, was used in the experiment. The uranium removal efficiency of Helianthus annuus L. for the real groundwater was higher than 95%, investigating that the rhizofiltration is the very useful method to remediate uranium contaminated groundwater.

• Journal of Soil and Groundwater Environment
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• v.13 no.4
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• pp.40-53
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• 2008

Groundwater pollution prediction methods have been developed to plan the sustainable groundwater usage and protection from potential pollution in many countries. DRASTIC established by US EPA is the most widely used groundwater vulnerability mapping method. However, the DRASTIC showed limitation in predicting the groundwater contamination because the DRASTIC method is designed to embrace only hydrogeologic factors. Therefore, in this study, three different methods were applied to improve a groundwater pollution prediction method: US EPA DRASTIC, Modified-DRASTIC suggested by Panagopoulos et al. (2006), and LSDG (Land use, Soil drainage, Depth to water, Geology) proposed by Rupert (1999). The Modified-DRASTIC is the modified version of the DRASTIC in terms of the rating scales and the weighting coefficients. The rating scales of each factor were calculated by the statistical comparison of nitrate concentrations in each class using the Wilcoxon rank-sum test; while the weighting coefficients were modified by the statistical correlation of each parameter to nitrate concentrations using the Spearman's rho test. The LSDG is a simple rating method using four factors such as Land use, Soil drainage, Depth to water, and Geology. Classes in each factor are compared by the Wilcoxon rank-sum test which gives a different rating to each class if the nitrate concentration in the class is significantly different. A database of nitrate concentrations in groundwaters from 149 wells was built in Keumsan area. Application of three different methods for assessing the groundwater pollution potential resulted that the prediction which was represented by a correlation (r) between each index and nitrate was improved from the EPA DRASTIC (r = 0.058) to the modified rating (r = 0.245), to the modified rating and weights (r = 0.400), and to the LSDG (r = 0.415), respectively. The LSDG seemed appropriate to predict the groundwater pollution in that it contained land use as a factor of the groundwater pollution sources and the rating of each class was defined by a real pollution nitrate concentration.

• Korean Journal of Soil Science and Fertilizer
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• v.24 no.1
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• pp.69-76
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• 1991

A pot experiment was conducted to find out the effects of lime and phosphate application on the changes of number of soil microorganisms, indigenous Rhizobium japonicum, nodule formation, and ureide-and amide-N in leaf and stem exudate of soybean plant under uncultivated hillside red earth in very low pH value, organic matter, available phosphate, and cation exchange capacity. The results obtained were summarized as follows : 1. The plant height, stem length, root dry weight and nodule weight were significantly increased with the application of lime and phosphate application than that of control plot. 2. The concentration of amide-N in soybean plant at the 45 days after sowing was obtained as high in order of control>lime> lime+phosphate while the concentration was obtained in order of Iime+phosphate>lime> control at flowering stage 3. However, concentration of ureide-N in the soybean leaf at the 45 days after sowing was obtained as high in order of control>lime>lime+hosphate while reversed concentration was obtained in stem. 4. The number of soil microorgan isms were increased with increase of pH value, available phosphate and soil exchangeable cation. 5. Significantly negative high correlation were obtained with the concentration of Al, Fe in soil and the concentration of amide-and ureide-N in soybean plant at flowering stage while positive correlation was obtained with plant growth and the concentration of ureide-N.

• Korean Journal of Medicinal Crop Science
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• v.8 no.3
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• pp.234-242
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• 2000

There are two cultivars, 'Jeongsun' and 'Mishima' of Bupleurum falcatum L., a medicinal plant, have been cultivated in Korea. Two cultivars were evaluated and compared in details for major growth characters and their seasonal changes. Jeongsun was higher in stem length and root weight per plant, and earlier in maturity than Mishima, while Mishima was higher in top weight per plant and the ratio of outer phloem layer(OPL) to whole root, and more in branch number. Coefficients of variations of most growth characters were higher in Mishima than in Jeongsun. In relationship between root and shoot growth characters, root weight, root diameter, etc. were positively correlated with stem thickness, top weight, branch number, etc. in both cultivars. In comparison of seasonal changes for growth characters between two cultivars, stem length and node number were almost not increased after September, but root length and branch number tended to increase until November. There were continuous increases of top and root weights in both cultivars after September. Increase rates of top and root weights were higher in Mishima and Jeongsun, respectively. The weight ratio of root part to whole plant in Jeongsun and the ratio of OPL to whole root in Mishima were higher during whole growth stages; especially Mishima showed their continuous increases after October. Jeongsun flowered earlier (August 17) than Mishima (September 16) by one month. Complete flowering date was on August 30 in Jeongsun and on September 30 in Mishima. Basic difference in plant growth between two cultivars was maturity, so shoot growth almost stopped after October in Jeongsun, and continued vegetative growth until November in Mishima with late flowering habit. These results indicate that higher root weight in Jeongsun is due to its earlier flowering character leading to relatively longer time for root growth, as compared with Mishima.

• Journal of the Mineralogical Society of Korea
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• v.17 no.1
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• pp.61-73
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• 2004

The purposes of this study are to investigate the occurrence, the hydrochemical characteristics and the origin of the $CO_2$-rich springs from the Kangwon Province, and to reanalyze the previous studied results of other researchers. The $CO_2$-rich water samples were collected at 13 locations in the Kangwon Province. The $CO_2$-rich water shows a high $CO_2$ concentration ($P_{CO2}$ 0.787 to 4.78 atm), weak acidic pHs, electrical conductivity values ranging from 422 to 2,280 $\mu$S/cm, and high Fe and F contents. The chemical compositions of $CO_2$-rich water from this study area are classified into three types; $Ca-HCO_3$, Ca(Na)-$HCO_3$, $Na-HCO_3$ types. The chemical data of $CO_2$-rich waters and their host rocks indicate that $Na-HCO_3$ type water are mainly influenced by biotite, K-feldspar granite, and Ca(Na)-HC $O_3$, type water is chiefly influenced by gneiss and carbonate minerals in granite. F and Fe contents of $CO_2$-rich waters are abundant in $Na-HCO_3$, and $Ca-HCO_3$ types, respectively. The results of this study suggest that the chemical composition $CO_2$-rich water is mainly controlled by the mineralogical composition of aquifer host rocks. Oxygen and deuterium isotope data indicate that $CO_2$-rich water is meteoric origin. The $\delta^{13}$C values (-0.3$\textperthousand$ to -6.2$\textperthousand$ PDB) suggest that dissolved carbonates are mainly derived from a deep-seated $CO_2$ and partly from carbonate minerals.

• Asian Journal of Turfgrass Science
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• v.18 no.2
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• pp.63-70
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• 2004

This study was conducted to figure out the effect of 'Methlyen Urea(MU)', slow released fertilizer and 'T-Vigor', microbial fertilizer as environment fertilizer on growth of 'Crenshaw' creeping bentgrass for environmental management in golf course. This study was conducted at No. 3, 4, 5 Valley Courses of Rexfield Country Club from April to July in 2004. MU, T-Vigor, sterilized T-Vigor were applied five times with 5g and 7.5ml per square meter, respectively. Polt size was 1 square meter and there were three replications with Completely Randomize Design. Collecting data were turf density$(No.\;of\;shoot\;/cm^2)$, chlorophyll $amount(\%)$, root length(cm), dry weight of clipping(g), and dry weight of root(g). The results are as follows; All of turf density, chlorophyll amount and dry weight(g) of MU and T-Vigor were better than control and sterilized T-Vigor. Especially root length of MU and T-Vigor was superior to control and sterilized T-Vigor, even if temperature and humidity was high. In conclusion, MU and T-Vigor might be used as slow release fertilizer for environmental green management in golf course.

• Geophysics and Geophysical Exploration
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• v.9 no.1
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• pp.67-72
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• 2006

Injection of $CO_2$ into underground saline formations, due to their large storage capacity, is probably the most promising approach for the reduction of $CO_2$ emissions into the atmosphere. $CO_2$ storage must be carefully planned and monitored to ensure that the $CO_2$ is safely retained in the formation for periods of at least thousands of years. Seismic methods, particularly for offshore reservoirs, are the primary tool for monitoring the injection process and distribution of $CO_2$ in the reservoir over time provided that reservoir properties are favourable. Seismic methods are equally essential for the characterisation of a potential trap, determining the reservoir properties, and estimating its capacity. Hence, an assessment of the change in seismic response to $CO_2$ storage needs to be carried out at a very early stage. This must be revisited at later stages, to assess potential changes in seismic response arising from changes in fluid properties or mineral composition that may arise from chemical interactions between the host rock and the $CO_2$. Thus, carefully structured modelling of the seismic response changes caused by injection of $CO_2$ into a reservoir over time helps in the design of a long-term monitoring program. For that purpose we have developed a Graphical User Interface (GUI) driven rock physics simulator, designed to model both short and long-term 4D seismic responses to injected $CO_2$. The application incorporates $CO_2$ phase changes, local pressure and temperature changes. chemical reactions and mineral precipitation. By incorporating anisotropic Gassmann equations into the simulator, the seismic response of faults and fractures reactivated by $CO_2$ can also be predicted. We show field examples (potential $CO_2$ sequestration sites offshore and onshore) where we have tested our rock physics simulator. 4D seismic responses are modelled to help design the monitoring program.