Effect Of Bagging On Fruit Quality And Pesticide Residue Of Mango

Mango (Mangifera indica L.) is known as 'the king of tropical fruits' Pro-harvest bagging on mango is a key technique to improve the fruit quality. Fenghuang mango,Renong No.l mango and Guifei mango are main cultivars in Hainan Province, which were used in the study. Fruit from three treatments, bagged with white paper bag (WB),yellow double paper bag (YB) and no bagged as control (CK), were harvest once per ten days after bagged for the fruit qualities test. Thiophanate-methyl and imidacloprid were sprayed in different ways after different bagging treatments to research the pesticide residues. Test results are as follows:1. The fruit weight, vertical and horizontal diameter and fruit index of 3 varieties mango were reduced at maturity after bagging treats, but the difference between 2 treatments was not significant. Fruit surface was more smoothly after treated with bag.Peel color was changed significantly after treated with yellow double paper bag for 10 d,white paper bag for 20 d.2. The decrease rate of vitamin C and total acid of Fenghuang mango, Guifei mango and Renong No.1 mango that treated with bagging were significantly faster than control. The soluble solids, total sugar and protein contents of the mango pulp were not significantly changed in the early days, but decreased significantly 40 d after bagged,and which were lower the YB treated than WB treated. Ripe Fenghuang mango treated with WB had a higher sugar-sour-ratio than the fruit treated with YB and CK. The sugar-sour-ratio of Guifei mango and Renong No.1 mango treated with YB were both higher than the fruits treated with WB and CK respectively.3. Residues level of thiophanate-methyl and its metabolite carbendazim and imidacloprid in mango pulp were determined by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) at the same time. The limits of detection (LODs), standard curve and correlation coefficient (r) were 0.5 ?g/kg,y = 608204x + 1534.7, r = 0.999 separately for thiophanate-methyl; 0.12 ?g/kg, y =111293x + 2628.32, r = 0.998 for carbendazim; 0.5 ?g/Kg, y = 4.08028e + 006x +8986.49, r = 0.999 for imidacloprid. The result showed that the test methord was credible.4. The treated with WB and YB were significantly reduce the pesticide residues of thiophanate-methyl in the pulp, bagging treated can accelerate the decrease of thiophanate-methyl, but no significant difference between 2 treatments. The total pesticide residues in bagging and control reached the highest level at 10 d and decreased to the safe range at 30 d. The tendency of the increase and decrease of the residual amount of thiophanate-methyl was earlier than that of carbendazim. The degradation of carbendazim was prolonged in 20 d, indicating that the residual period of carbendazim was longer than that of methyl thiophanate.5. When the pesticides were sprayed several times, bagging can still effectively reduce the amount of pesticide residues in the pulp. Pesticide residues in the fruit mature period has a downward trend. The total pesticide residues of CK was continuously increased to the maximum at the first 50 d (sprayed 4 times), the WB treated peak at 40 d (spayed 3 times), and both were out of safe range. The total pesticide residues of WB treated were decreased to safe range at 60 d.6. The pesticide residues distribution in different parts of mango was significantly different.The total pesticides residues of thiophanate-methyl and carbendazim were mainly concentrated in the peel, and imidacloprid was both high in the peel and pulp.Bagging can reduce the pesticide residues in the peel, but no significant impact on the pulp. Imidacloprid has a strong internal absorption on mango, more than thiophanate-methyl.