Influence Of Bagging On Pesticides Residues In Muskmelon

In this study Jinyu and M135were used as materials, Carbendazim and Dichlorvos wereused as tesed pesticides, muskmelon fruits were bagging treated with paper bags and plasticbags, compared with no bagged fruits(control) in solar-greenhouse. Investigated the effects ofdifferent bag materials, type pesticides and pesticide concentration on the pesticide residues inthe bagged fruits, and the accumulation pattern of pesticide residues. The main results were asfollows:1. Bagging decreased the pesticide residues by about37.2%-77.9%in fruit, through blockingthe direct contact of fruit and pesticide. The results of investigating the effect of bagmaterials on pesticide residues showed that the white paper bag was slightly better thanplastic bag, but compared with control, the pesticide residues reduced by77.9%and70.0%respectively, but the different bag materials had some difference.2. The pesticide residues showed different degree of rising trends with the increase ofspraying frequency. The pesticide residues was highest in Jinyu, after the third spraying,the residues of Carbendazim and Dichlorvos in no bagged mature fruits reached to0.599mg/kg and0.786mg/kg, respectively, which all above the maximum residue limits invegetables established by China (MRLs) by50%and7%, while the pesticide residues didnot exceed the limit standard in the bagged mature fruits of Jinyu.3. The experiment showed that the residues of Carbendazim and Dichlorvos in fruits reachedto the highest on the1st and5th day after spraying, respectively, so in comparison withnon-absorption pesticides, such as Dichlorvos, the ues interval of the systemic pesticideslike Carbendazim were more difficult to control, resulting in high residues, and existingsecurity risk.4. The experiment results of different pesticide concentration suggested that when theconcentration of Carbendazim above300times，the Carbendazim residues in no bagedand no peeled Jinyu fruits exceeded MRLs by20%. When the concentration of Dichlorvosabove1000times, the residues in Jinyu fruits all exceeded MRLs on the first day after spraying. Therefore when the concentration of Carbendazim above300times, or theDichlorvos above1000times, the pesticide residues were higher, were not beneficial tothe quality and safety production of muskmelon.5. The analysis of epidermal characteristics and anatomical structure of Muskmelon fruitshowed that the surface of M135fruit had obvious wax, epidermal cells tightly packed,and cell gap was smaller, while the surface of Jinyu had no obvious wax, showed a looserarrangement of epidermal cells, and a larger cell gap, resulting in the Dichlorvos residuesof Jinyu fruit were more than M135.6. Pesticide residues were mainly concentrated in the Epicarp, for the Carbendazim, theresidues in endocarp were more than that in mesocarp, whereas for the Dichlorvos, theresults was contrary. It demonstrated that the enrichment sites of the pesticide residues infruit were related to the nature of pharmaceutical.