脆蜜金柑喷施噻苯隆保果的残留研究

Study on the residue of thidiazuron in Cuimi kumquat fruit after spraying thidiazuron for fruit-protection

噻苯隆是脆蜜金柑生产上常用的保花保果剂,其残留风险未知。为探明噻苯隆在脆蜜金柑上使用后的残留和降解变化规律,使用6种浓度(5.00、2.50、1.66、1.25、1.00和0.83 mg/kg)的噻苯隆混合配方(同时加赤霉酸13.3 mg/kg、复硝酚钠9.5 mg/kg)在脆蜜金柑谢花盛期开始进行树冠喷施,连喷3次,间隔6~8 d喷一次,于末次喷施后1、3、5、7、9、12、17、25、35和105 d分10批次采集果实样品检测残留。结果表明,末次施药后3 d时所有处理果实的噻苯隆残留量已经低于0.05 mg/kg(国家标准规定在番茄、黄瓜、苹果、葡萄、鲜枣、甜瓜类水果等6种农产品中的最大残留量),末次施药后35 d生产上常用浓度(1.25 mg/kg)处理的果实噻苯隆残留已经低于0.001 mg/kg,末次施药后105 d各处理果实噻苯隆残留量均低于0.0003 mg/kg、无法检出,末次施药后145 d采收上市的果实不存在食品安全风险;噻苯隆1.0 mg/kg使用3次或1.25 mg/kg使用2次即可能对脆蜜金柑幼果、叶片和树体健康造成伤害。脆蜜金柑生产上采用噻苯隆保花保果时,建议使用浓度以1.0 mg/kg左右为宜,使用次数不超过3次,施药第一、二次间隔期6~8 d,第二、三次间隔7~10 d。

Thidiazuron is a commonly used flower and fruit protection agent in the production of Cuimi kumquat,and its residual risk is unknown.In order to explore the residual and degradation changes of thidiazuron in Cuimi kumquat fruits after application,6 concentrations(5.00,2.50,1.66,1.25,1.00 and 0.83 mg/kg)of thidiazuron mixed with gibberelic acid 13.3 mg/kg and sodium nitrophenolate 9.5 mg/kg were used for crown spraying of Cuimi kumquat from the full-bloom stage with three times continuously spraying at an interval of 6-8 days.Fruit samples were collected in 10 batches at 1,3,5,7,9,12,17,25,35 and 105 days after the last spraying for residue detection.The results showed that the thidiazuron residues in the treated fruits at 3 days after the last application were lower than the threshold of maximum residue(0.05 mg/kg)specified in the relevant national standards.The thidiazuron residues in the fruits treated with the commonly used concentration of 1.25 mg/kg in production were lower than 0.001 mg/kg at 35 days after the last application.The thidiazuron residues in the fruits treated with the commonly used concentration(1.25 mg/kg)in production were lower than 0.0003 mg/kg at 105 days after the last application and could not be detected.There was no food safety risk in the fruits harvested for marketing at 130 days after the last application.However,the use of 1.0 mg/kg thidiazuron for 3 times or 1.25 mg/kg for 2 times may cause damage to the young fruits,leaves and growth of the trees of Cuimi kumquat.When thidiazuron is used to protect flowers and fruits,it is recommended to use a concentration of about 1.0 mg/kg and spraying for no more than 3 times.The interval between the first and second applications,the second and third applications were 6-8 days,7-10 days,respectively.