Residue Of Fluopicolide In Tomato And Its Effects On Physiological And Biochemical Properties And Edible Qualities Of Tomato

As a new type of benzamide group of fungicides developed by Bayer Company,fluopicolide is mainly used to control diseases caused by oomycete pathogens such as downy mildew,late blight,Phytophthora blight and so on.At present,fluopicolide has been registered in the world for use in grapes,root and tuber vegetables,brassica leafy vegetables,bulb vegetables,fruiting vegetables and cucurbits.Since it was allowed to register by Ministry of Agriculture of the People's Republic of China in 2005,fluopicolide has been mainly used to control downy mildew of grape,cucumber and Chinese cabbage,late blight of potato and tomato,and Phytophthora blight of pepper and watermelon.At present,there are few reports on residue and dissipation behavior of fluopicolide or effect of fluopicolide on crops.In this thesis,residue and dissipation behavior of fluopicolide,its effects on physiological and biochemical characters of tomato and its edible and nutritional qualities were systematically studied after 20%fluopicolide suspension emulsion was applied to tomato fields.This study will provide a scientific basis for the safe use of fluopicolide in the tomato fields.The main results were summarized as follows:In this paper,a new method was developed for the residual analysis of fluopicolide by ultraperformance liquid chromatography-mass spectrometry?UPLC-MS/MS?in tomato and soil.The fluopicolide in samples was extracted with aqueous acetonitrile,separated on a C18 reverse phase column using aqueous acetonitrile and methanoic acid as mobile phase,and detected with positive ionization electrospray ionization-mass spectrometry under a multiple reaction monitoring?MRM?mode.The limit of quantitation of fluopicolide for tomato fruit and soil were 1.0?g·kg^-1and1.7?g·kg^-1,respectively.The limit of detection for them were 0.3?g·kg^-1and 0.5?g·kg^-1,respectively.The average recoveries of fluopicolide ranged from 92.43 to 103.32%in tomato fruit and 92.75 to 104.46%in soil,with RSD varying from 3.8 to 4.9%and 3.4to 4.4%,respectively.The sensitivity,accuracy and precision of this method could meet the requirements of pesticide residue analysis.The experimental results in Heilongjiang province in 2014 and 2015 showed that the dissipation behavior of fluopicolide in tomato fruit and soil followed the first-order reaction kinetic model.In 2014 and 2015,the half-life of fluopicolide in tomato were6.38 d and 6.41 d,respectively,and the half-life in soil were 8.29 d and 6.48 d,respectively.Final residues of fluopicolide in tomato fruit and soil were studied in the experimental fields in Heilongjiang province in 2014 and 2015.The pesticide was applied in two groups according to the dose.The effective content was 1125 g·ha^-1 in low dose group,and it was 1687.5 g·ha^-1 in high dose group.In each dose group,the pesticide was applied three times and four times,respectively.The interval was 7 days.The final residue of fluopicolide in tomato fruit and soil were analyzed on the 3rd,5th and 7th day after the last application,respectively.The results showed that the final residue of fluopicolide increased as the application dose and application times increased,or as the harvest interval decreased.The results also showed that the maximum residue of fluopicolide in tomato fruit and soil were 0.994 mg kg^-1 and 0.890 mg·kg^-1,respectively.The effects of fluopicolide on physiological and biochemical properties of tomato were studied.20%fluopicolide suspension emulsion was sprayed one time upon the tomato in the experimental fields in Heilongjiang and Jiangsu provinces and Tianjin at the dose of 1125 g ha^-1?a.i.?at the part of the growing season in 2014.The results showed that compared with the control malondialdehyde and proline contents and superoxide dismutase and catalase activities in tomato fruit increased,and peroxidase activity increased in general.20%fluopicolide suspension emulsion was sprayed one time upon the tomato in the experimental fields in Heilongjiang and Jiangsu provinces and Tianjin at the dose of1125 g ha^-1?a.i.?in 2014.Moisture,reducing sugars,organic acids,vitamin C and lycopene contents in tomato were analyzed on the 2nd hour and 1st,2nd,3rd,5th,7th,10th,14th,21th,28th and 45th day after fluopicolide was applied,respectively.The results showed that these indexes were not remarkably affected by dose of the pesticide or interval between the last application and harvest.