Study On Residue Of Chlorpyrifos And Efficacy Of Spraying Of Brassinolide And Salicylic Acid In Ya Pear Fruits

Chlorpyrifos is a moderately toxic organophosphorus pesticide which can effectively prevent and control a variety of main pests in pear production and is widely used in the pollution-free fruit production. According to the problem of excessive CPF residues in the export fruits, we conducted the research on Ya pear(Pyrus bretschneideri. Kehd cv. Yali) mature fruits and the residue of CPF in fruits was analyzed by using the acetonitrile extraction and Gas Chromatograph. We carried out the relevant studies and eventually made sure that the exogenous substances Brassinolide(BR) and Salicylic Acid(SA) could effectively promoted the degradation of CPF and the effects of residue correlation factors on final residue in Ya pear fruits in order to guide safety production and promote the degradation of CPF residues in Ya pear fruits. Main results were as follows:1. BR and SA could effectively promote the degradation of CPF, 0.5 mg/L BR and 100 mg/L SA were the most suitable concentration respectively.2. In the field experiment, the residual degradation dynamics of CPF in the peel and in the whole sprayed in the middle of July were:The peel: C=17.888e-0.0411t(r=0.9435), the half-life: T1/2=16.86 d.The whole fruit: C=2.1021e-0.068t(r=0.9324), the half-life: T1/2=10.19 d.Residual degradation dynamics all accorded with C=C0e-kt, and all had high relativity. In normal conditions, CPF degradation was very fast and it was easily degraded in the environment.3. For all parts of the fruits, we took methods to avoid direct contact with CPF, the bagging fruits would still be detected in the CPF, and the residue order of CPF in different position of Ya pear was: stalk >peel>other parts of the fruit. The results showed that CPF was a kind of systemic pesticides which might be one of the reasons for the source of CPF in the bagging fruits. But bagging could obviously reduce the CPF residues in pear fruits, so it was an effective cultivation technique.4. The CPF residues mainly remained in the peel and the pulp remained relatively low. So peeling the fruit can remove most of the pesticide residues.5. The times of spraying and the postharvest storage temperature could influence the final residue of CPF. The more spraying times, the greater the CPF residue; compared with the room temperature(25℃), postharvest cold storage(8℃) would hinder the CPF degradation to a certain extent.6. In the field experiment, Ya pear fruits treated with three times by the CPF pesticide stored in the room temperature would meet the EU export standard after 25 days. Stored in the cold temperature(8℃) would meet the standard after 36 days. After treatment with BR, the fruits stored in the cold temperature would meet the standard after 25 days, 10 days before than those without exogenous substance. And samples treated by SA could also reach the standard in advance and the effect of BR was better than SA in promoting the degradation of CPF.