The Residue Behavior And Effects Of Propamocarb In Tobacco Fields

In order to study the residual behavior of Propamocarb and related preparations used in the tobacco fields and accurately assess the ecological environmental effects of Propamocarb, this article established a method for analysis and detection of residues of the tobacco field samples by adding recovery experiment. After that, the article study the effects on quality of tobacco by Pot and field experiments. This study analyzed the residual and degradation of propamocarb systematically in tobacco soil and leaves. Its adsorption was probed in the four kinds of Clay minerals. The main results are as follows:1Propamocarb has little effect on the growth of the tobacco plants, however, lightly phytotoxicity could be observed latterly while sprayed high concentrations of propamocarb.2The method of GC analysis of propamocarb was established by extracting with acetonitrile and purifying with neutral alumina column. The propamocarb residues in tobacco leaves and soils were analyzed by Gas Chromatography (NPD). In this method the residues of propamocarb were extracted with Acetonitrile, then calculated the content of propamocarb in tobacco. The minimum detectable amount of propamocarb was1.0xl0-10g.while the minimum residue in tobacco soil, leaves were0.05mg/kg. Results showed that the fortified recoveries in different samples ranged from80.66%-96.92%and relative standard deviation ranged from2.82%-9.03%when the added concentration of propamocarb ranged from0.20to5.00mg/kg.3Field experiments were carried out to reveal residue dynamics and final residue of propamocarb in tobacco leaf and soil in Changsha and Qingdao. Results showed that the half-lives in soil and leaves ranged in2.30-2.84days and2.86-4.14d days, respectively. It means that propamocarb is degradable pesticide.The final residue results showed that the ultimate residue in dry leaves was lower than2.0mg/kg at an interval of7d. According to the results, when51%soluble powder of propamocarb were sprayed in tobacco field for four times according to the recommended dose of600g.hm/2(306a.i.g.hm/2), the safe period of propamocarb in tobacco leaves could be set as7d.4Not only Propamocarb could not transport between plant and soil, but also coould not transport between top of tobacco leaves and botton of tobacco leaves. And Propamocarb could not transport in the same leaf. Therefore the performance of Propamocarb is contact residues, translocation of Propamocarb is small.5The adsorption equilibrium times of propamocarb were20hours. The adsorption of propamocarb in four kinds of clay mineralcould be described with the Liner isotherm equation. The adsorption of propamocarb was strongest in the montmorillonite; the adsorption was weakest in the Kaolin; pH played an important role in the adsorption, at different pH values the adsorption of propamocarb were different.