Effects Of Exogenous Brassinolide On Avermectin And Vitamin Cin Celery Degradation Dynamics Of Phoxim

Celery is a common vegetable.In recent years,the problem of pesticide residues in celery products is more prominent.Hormone levels in organs will affect the metabolism and residues of pesticides.In order to study the degradation dynamic effect of Brassinolide(BR)on avermectin and Phoxim Residues in celery,two kinds of pesticides avermectin and phoxim with the largest detection amount in celery products were analyzed by Qu ECh ERS method combined with high performance liquid chromatography.This experiment was conducted to investigate the natural degradation of two pesticides in celery and the effect of exogenous Brassinolide on the degradation,and to determine the activities of detoxification enzymes.The main results are as follows:1.Blank addition of avermectin and phoximThe concentration of Avermectin in celery was 0.05 mg/kg~1.0 mg/kg,the average recovery rate was79 % ~93 %,and the relative standard deviation was 3.32 % ~6.46 %.The concentration of Phoxim in celery was 0.05 mg/kg~0.6 mg/kg,the average recovery rate was 81 % ~92 %,and the relative standard deviation was 4.74 % ~6.17 %.2.The effect of exogenous Brassinolide on the degradation of Avermectin in celery organsThe original residue of Avermectin in celery organs was 0.4263 mg/kg after 1.8 % avermectin was sprayed.Under the condition of natural degradation,the half-life was 6.6 days and the safe recovery period was 21 days.The results showed that the original residue of Avermectin in celery organs was 0.3826 mg/kg,and the residual amount was not detected at 21 days.The results showed that the residual amount of Avermectin in celery organs was 0.3826 mg/kg,and the residual amount was not detected at 21 days after administration,and 9.17 %,10.11 %,19.82 %,31.72 %,52.32 % were decreased compared with the control at 1,3,5,7,14 days after administration.The half-life of celery was 4.03 days and the safe recovery time was 14 days,7days earlier than that of the control group.The results showed that the original residue of Avermectin in celery organs was 0.3810 mg/kg,and 10.84 %,56.03 % and 58.39 % respectively lower than that of the control group at 1,3,7 days after administration.The half-life of celery was 2.11 days and the safe recovery time was 7 days,14 days earlier than that of the control.3.The effect of exogenous Brassinolide on the degradation of Phoxim in celery organsThe original residual amount of Phoxim in celery organs was 0.7472 mg/kg after 40 % phoxim emulsion was sprayed.Under the condition of natural degradation,the half-life was 3.04 days and the safe recovery period was 14 days.The results showed that the original residual amount of Phoxim in celery organs was 0.4434 mg/kg,and the residual amount was not detected at the 14 th day.The residual amount at 1,3,5,7 days after administration was 43.64 %,68.91 %,77.85 %,78.80 % lower than that of the control.The half-life of celery was 1.83 days and the safe recovery time was 7 days,7 days earlier than that of the control group.The results showed that the original residual amount of Phoxim in celery organs was 0.4423 mg/kg,and the residual amount was not detected at the 7th day.The results showed that the amount of Brassinolide(1,2 and 3 times)was the best one,of which 43.71 % and 85.46 % were decreased at the first and third days after administration.The half-life of celery was 1.05 days,the safe recovery time was 7 days,7 days earlier than that of the control.4.Effects of exogenous Brassinolide on the final residues of avermectin and phoxim in celery organsSpraying abamectin and phoxim at 1.5 times of recommended dose and three times of high frequency,spraying different concentrations of Brassinolide(0.01,0.05,0.1,0.5 mg/L)on the first day before spraying.The optimal spraying concentration was 0.1 mg/L BR.The residues of Abamectin and phoxim were 0.1159mg/kg and 0.1091 mg/kg respectively on the 14 th day after the last spraying,which were 67.76 % and62.22 % lower than the control,respectively.The residue of Abamectin and phoxim was 0.1159 mg/kg and0.1091 mg/kg on the 21 st day after spraying The residue was not detected.Brassinolide was sprayed for different times(1,2,3 times)on the first day before spraying.The optimal spraying times were 2 times of BR.The residues of avermectin and phoxim were 0.0840 mg/kg and 0.0731 mg/kg respectively on the 14 th day after the last spraying,which were 76.63 % and 74.69 % lower than the control.The residues were not detected on the 21 st day.No matter under natural degradation or BR treatment,avermectin and phoxim residues were not detected at 21 days,which were lower than the maximum residue limit(MRL)(0.05mg/kg).5.Activity of related detoxification enzymesThe activities of peroxidase(POD),glutathione reductase(GR)and glutathione S-transferase(GST)in celery tissues were significantly increased by different concentrations of BR(0.01,0.05,0.1 and 0.5 mg/L),and the POD activity was the highest when 0.5 mg/L BR was sprayed,Compared with the blank control,it increased by 55.70 % and 45.66 % respectively;spraying 0.5 mg/L BR,the activity of GR in celery tissue was the highest,increased by 150.33 % and 29.04 % respectively;spraying 0.1 mg/L BR,the activity of GST in celery tissue was the highest,increased by 32.56 % and 153.33 % respectively.The results above are expected to provide scientific basis for the safe and reasonable application of avermectin and phoxim in celery production.