| Southern Xinjiang is one of the main cotton producing areas in Xinjiang,and the cotton stalk accounts for about one-third of the agricultural straw every year in this area.It is the best way to reuse cotton stalk that is to be used in cultivation of edible fungi,and the stalk contains high protein.However the pesticide residue in cotton stalk is the green barrier to the safe production of edible fungi.In this study,the pesticide residues in fruiting bodies of cotton stalks and their alternative substrate were detected and analyzed by investigating the application of pesticides in cotton fields in southern Xinjiang,and the risk of pesticide residues in cotton stalks in three cotton planting areas in southern Xinjiang was evaluated.The main results are as follows :(1)The use of pesticides in the main cotton planting areas in southern Xinjiang was investigated by means of literature review,visits to agricultural materials stores and questionnaires.The results showed that the educated level of local cotton farmers was mainly junior high school culture(62.5%),and there were few ways to understand pesticide knowledge and pest control,mainly through the promotion of pesticide salesmen,the guidance of plant protection technicians and their own production experience.Little is known about the prohibition of highly toxic pesticides in cotton.According to the statistics of pesticide types,about 30 kinds of chemical pesticides were used in the main cotton planting areas in southern Xinjiang,among which the use of chemical regulators was the most,and the use of each growth cycle in Shajingzi planting area was up to 16 times.During the growth period of cotton,the farm chemicals used most was insecticide,among which pesticides for aphids was up to 11.(2)Liquid chromatography-tandem mass spectrometry(HPLC-MS/MS)was used to preliminarily screen the residues of 30 pesticides in cotton stalks,and it was preliminarily determined that imidacloprid,acetamiprid,pendimethalin,tetrazine,thidiazuron and mepiquat chloride in cotton stalks had residues in cotton stalks.The pesticide residues in cotton stalk samples from different cotton planting areas in southern Xinjiang were further detected by liquid chromatography-tandem mass spectrometry.The results showed that the highest residue of mepiquat chloride in cotton stalk was 338.644 μg/kg,followed by acetamiprid(45.3779 μg/kg)and thidiazuron(1.4437 μg/kg).The residues of mepiquat chloride,acetamiprid and thidiazuron were 256.6612 μg/kg,53.4581 μg/kg and 0.2193 μg/kg,respectively.The residues of mepiquat chloride,acetamiprid,thidiazuron and pendimethalin in cotton stalk were 280.9205 μg/kg,48.3968 μg/kg,0.3753 μg/kg and 0.2529 μg/kg,respectively.(3)The cotton stalk samples from different cotton planting areas were used to cultivate Pleurotus ostreatus,and the fruiting bodies of Pleurotus ostreatus were taken for pesticide residue detection.The results showed that mepiquat chloride was detected in the fruiting body of Pleurotus ostreatus.The residual range of mepiquat chloride in the cotton stalk substitute cultivation of Pleurotus ostreatus in Shajingzi cotton planting area was 121.8452-153.3454 μg/kg,and the residual range in Maigaiti planting area was7.6618-144.4726 μg/kg.The single pollution index of the residual meperium in Pleurotus ostreatus cultivated with cotton stalk substitute in different planting areas was evaluated.The results showed that the pollution index in Shajingzi planting area was grade I;the pollution index of the Maigaiti planting area was grade I and grade II,respectively,indicating that the use of mepiquat chloride in the cotton planting area was unreasonable,which brought certain safety risks to the cultivation of edible fungi by cotton stalks in this area. |
