Effects Of Spraying Thiophanate-methyl And Mancozeb On Nutrient Quality Of Sesame

The effects of fungicides thiophanate-methyl and mancozeb on treatment of the diseases and nutrients were studied in the research. It could also provide a scientific basis for the safety of pollution-free sesame production. The field experiments were carried out in Zhenping county and Zhengzhou city of Henan Province. The sesame variety Yuzhi No.11 and Zhengzhi No.98N09 were used in the study. The design of randomized trials was applied. We adopted the local production management districts.The fungicide of 70% thiophanate-methyl 400 times was sprayed in the flowering stage and the end of flowering. The diseases of sesame on the leaf and stem and capsule had been controlled effectively.The sesamin and sesamolin in sesame were extracted by ultrasonic.By means of analyzing the single factor experiments and the orthogonal experiments, the conditions of extraction were optimized as follows: n-hexane/MeOH(60/40) as recovered solvent, the ratio of liquid to material was 30:1(mL/g), the ultrasonic machine running 12 minutes in 65℃.The contents of sesamin and sesamolin were detected by HPLC. The condition of chromatogram was confirmed as follows: chromatographic column: Agilent(C18 250 mm×4.6 mm, 5μm), the system of elution: methanol:water=80:20(V:V),the speed of fluxion:1mL/min,the temperature of column:35℃, the wavelength of determination: 290nm. The C18, enhancing the purified effect and decreasing the inspectional molestation, was adopted in the Pre-Processing of sample.After spraying the fungicides of thiophanate-methyl and mancozeb for the treatment of diseases, the effects on the nutrients in sesame seeds had been researched for two years. The sprayed consistency and times and sprayed medicines had not significant impacts on the nutrients in the sesame seeds in general. Of these, 400 times of 70% thiophanate-methyl WP in two times had more significant influence on the crude fat content of Zhengzhi No.98N09; In the case of the control group of Yuzhi No.11, 800 times of 70% mancozeb WP in two times, 800 times of 70% mancozeb WP in one time, 400 times of 70% mancozeb WP in two times had relativity among them as a result of the significant impact on the crude fat content; for Zhengzhi No.98N09, 800 times of 70% mancozeb WP in one time and 800 times of 70% thiophanate-methyl WP in one time had significant effect on raising the crude protein contents; for Yuzhi No.11, 400 times of 70% mancozeb WP in two times had significant effects on raising the contents of palmitoleic and stearic acid and oleic acid; 800 times of 70% mancozeb WP in two times had significant effects on raising the contents of sesamin and sesamolin in sesame seeds; spraying fungicide mancozeb had no significant effect on raising the contents of manganese and zinc in sesame seeds.The rapid simultaneous determination of residues of thiophanate-methyl and its metabolite carbendazim was developed in the study, which was extracted with acidic acetonitrile, and purified with C18 and PSA, then detected by the high performance liquid chromatography in the end. The condition of chromatogram was confirmed as follows: chromatographic column: Agilent(C18 250 mm×4.6 mm, 5μm), the wavelength of determination: 268nm(thiophanate-methyl),286nm(carbendazim), the system of elution: A:B=55:45(V:V), the speed of fluxion:1.0 mL/min, the temperature of column:30℃, the retention time: 4.06 min(carbendazim),6.42 min(thiophanate-methyl). The residues of thiophanate-methyl and carbendazim in sesame were lower than 0.5 mg?kg-1, but higher than the standard of pollution-free sesame(carbendazim, 0.2 mg?kg-1 ). So when treating the diseases of pollution-free sesame, the doses of 70% thiophanate-methyl WP must be reduced on the basis of the experiment. The MRLs of thiophanate-methyl, which was conversed from the MRLs of carbendazim in pollution-free sesame, had been recommend for 0.36 mg?kg-1 in the indexs of pollution-free sesame.The rapid determination of residue of mancozeb's metabolite ethylene thiourea(ETU) was developed in the experiment, which was extracted with methanol, and purified with C18 and PSA, then detected by the high performance liquid chromatography in the end. The condition of chromatogram was confirmed as follows: chromatographic column: AichromBondAQ-C18(250 mm×4.6 mm, 5μm), the wavelength of determination: 234nm, the system of elution: water: methanol = 85:15(V:V), the speed of fluxion:0.8 mL/min, the temperature of column:35℃. The mancozeb, which was a protective fungicide, had no significant effect of treating diseases in sesame. When being sprayed too large, It must lead to metabolic product of mancozeb residue exceeding the MRLs in sesame, which would be harmful to the production of pollution-free sesame.