| Flumorph is a new morpholine fungicide, commonly used to control the Black stem disease of tobacco. Previous studies focused mainly on its efficacy, toxicity, and fungicidal mechanism, and little information was available about its behavior and ecological effect in tobacco field. The pesticide residual behavior and effect of flumorph in tobacco field were studied in this thesis in order to provide some fundamental data for assessing the eco-environment safty, and guiding scientific application of flumorph.(1) The determination method of flumorph in tobacco and soil planted tobacco was established. Under the given liquid chromatography condition, the average recoveries of flumorph in tobacco and soil planted tobacco ranged from 93.38% to 95.12% with relative standard deviations changed from 2.67% to 5.52%, and its minimum detectable limit was 6.4×10-10g, the lowest concentration detected was 0.008mg/kg in fresh tobacco and soil,and 0.016mg/kg in dry tobacco.The sensitivity and precision of this method could meet the requirements of pesticide residue determination.(2) The degradation procedure of flumorph on tobacoo field could be scribed by first-order kinetics equation, Ct=C0e-kt. Its half-live in tobacco were T1/2,2008=13.72d and T1/2,2009=13.37d, and in soil planted tobacco were T1/2,2008=15.54d and T1/2,2009=15.57d in Hunau changsha; its half-live in tobacco were T1/2,2008=11.85d and T1/2,2009=12.83, and in soil planted tobacco were T1/2,2008=15.26d, T1/2,2009=15.68d in Shangdong qingdao. The results showed that flumorph was degraded quickly in tobacco field after application(T1/2 < 30d).(3) The residue of flumorph ranged from 0.732 mg/kg to 1.287 mg/kg in soil planted tobacco and from 0.188 mg/kg to 0.457 mg/kg in dry tobacco on 21th day after the last application, when 5% flumorph wp (180 a.i.g/hm2 and 120 a.i.g/hm2) was poured to the root of tobacco for 3 or 4 times in fast growing period of tobacco, The concentrations of flumorph were all lower than 2.0 mg/kg. As European Union and our country have not formulated MRL of flumorph in tobacco and other crops, referring to GRL (2.0mg/kg) of dimethomorph formulated by CORESTA. if MRL of 2.0 mg/kg for flumorph in tobacco was proposed in our country, tobacco leaf should be harvested on 21th day or after 21th day after the last application.(4) The results showed that the flumorph could inhibit the respiration of soil planted tobacco, and the phenomenon has presented "Inhibition→activation→re-inhibition" trend. However, this trend was not sustained.This effects on the respiration of soil planted tobacco recoveried gradually to normal levels after 30th day. The differences of release of CO2 in soil planted tobacco were not significant between theated concentration of flumorph and CK by T test, and it was also no significant difference between different theated concentration of flumorph, the harm factor of flumorph in soil planted tobacco was less than 20. So that flumorph belonged to low toxicity fungicide in tobacco field。(5) Flumorph stimulated the activitis of urease in soil planted tobacco at the low concentration(1mg/kg,10mg/kg), and inhibited the activity at the high concentration (50mg/kg). Effect of flumorph on catalase in soil planted tobacco displayed a process of "activation→inhibition" at the low concentration, while at the high concentration the activity of catalase was inhibited, but this effect disappeared gradually after treated 30th day.(6) Intensity of soil nitrification was significantly suppressed during the entire cultural process, when flumorph was added to the soil planted tobacco, and this effect had disappeared after treatement on 30th day. The results also showed that flumorph caused the intensity of soil ammonification to be inhibited significantly, the inhibition accorded with the increasing of concentration of flumorph during the early days, and this inhibital effect on soil ammonification was still present after treatement on 30th day. |
PDF Full Text Request