• Journal of the Korean Society of Tobacco Science
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• v.27 no.1 s.53
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• pp.11-18
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• 2005

The nicotine converter genotypes of burley tobacco (Nicotiana tabacum L.), which convert nicotine to nornicotine, contain a high amount of nornicotine that degrades tobacco quality and smoking taste. Elimination of nicotine converter plants before seed harvesting is required for breeding nicotine low-converter lines and for increasing their seed production. This study aims to develop a rapid and convenient method of identifying nicotine converter plants of burley breeding lines of KB9118(KB108) using thin-layer chromatography (TLC) and isatin coloration method. Out of 223 plants in 10 lines harvested at maturity in 2002, 102 plants ($45\%$) were identified as nicotine converters by TLC of tobacco leaves air-cured. For 16 lines selected as low-converters in 2002, 148 plants grown in the field in 2003 were tested by the isatin coloration method using two detached leaves at the flowering stage thoroughly sprayed with $1\%\;NaHCO_3$ solution and cured in conditioned chambers for the early identification of nicotine to nornicotine conversion. From these samples, 46 plants ($31\%$) in 4 lines were identified as nicotine converters, indicating that the ratio of converters significantly decreased by one time selection. Mean percent conversion of non-screened lines was $14\%$ higher than that of following generation. Therefore in the burley tobacco, a rapid and convenient means of identifying and removing nornicotine converter plants by the isatin coloration method during growth in the greenhouse or field were effective in reducing the converter plants in the following generation.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.121-121
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• 2004

The groundwater in the Pocheon area occurs from both a fractured bedrock aquifer in igneous and metamorphic rocks and an alluvial aquifer with a thickness of <50 m, and forms a major source of domestic and agricultural water supply. In this study, we performed a hydrogeochemical study in order to identify the control of geochemical processes on groundwater quality. For this study, groundwater level and physicochemical parameters (EC, Eh, pH, alkalinity) were monitored once a month from a total of 150 groundwater wells between June 2003 to August 2004. A total of 153 water samples (13 surface water, 66 alluvial groundwater, 74 bedrock groundwater) were also collected and analyzed in February 2004. Groundwater chemistry in the study area is very complex, depending on a number of major factors such as geology, degree of chemical weathering, and quality of recharge water. Hydrochemical reactions such as the leaching of surficial and near-solace soil salts, dissolution of calcite, cation exchange, and weathering of silicate minerals are proposed to explain the chemistry of natural groundwater. Alluvial groundwaters locally have very high TDS concentrations, which are characterized by their chloride(nitrate)-sulfate-bicabonate facies and low Na/Cl ratio. Their grondwater levels are highly fluctuated according to rainfall event. We suggest that high nitrate content and salinity in such alluvial groundwaters originates from the local recharge of sewage effluents and/or fertilizers. Likewise, high concentrations of nitrate were also locally observed in some bedrock groundwaters, suggesting their effect of anthropogenic contamination. This is possibly due to the bypass flow taking place through macropores. Tile degree of the weathering of silicate minerals seems to be a major control of the distribution of major cations (sodium, calcium, magnesium, potassium) in bedrock groundwaters, which show a general increase with increasing depth of wells. Thermodynamic interpretation of groundwater chemistry shows that the groundwater in the study area is in chemical equilibrium with kaolinite and Na-montmorillonite, which indicates that weathering of plagioclase to those minerals is a major control of hydrochemistry of bedrock groundwater. The interpretation of the molar ratios among major ions, as well as the mass balance calculation, also indicates the role of both dissolution/precipitation of calcite and Ca-Na cationic exchange as bedrock groundwaters evolves progressively.