乙氧磺隆对烟草的早期药害症状识别及风险管控

Early identification of phytotoxicity symptoms and risk control of ethoxysulfuron on tobacco

[目的]磺酰脲类除草剂乙氧磺隆在我国烟-稻轮作区广泛使用,正确识别乙氧磺隆的药害症状,明确导致药害发生的原因及阈值,有助于保障烟草生产安全。[方法]采用大田试验和室内盆栽试验相结合的方式,研究了乙氧磺隆残留导致烟草产生的药害症状。[结果]大田试验结果表明,乙氧磺隆残留会导致烟草叶片黄化和褶皱,烟株矮小,严重时会导致烟株枯萎死亡。室内盆栽结果表明,乙氧磺隆残留与烟草药害之间呈现明显的“剂量-效应”关系。随着乙氧磺隆暴露剂量的增大,其对烟草株高和叶面积的抑制作用逐渐增强。在施药后30 d,30μg/kg处理组乙氧磺隆对烟草株高和叶面积的抑制率均超过10%。在高剂量处理组,乙氧磺隆导致烟草叶片中叶绿素含量和生长素(IAA)含量显著减少,而脱落酸(ABA)含量显著增加,这可能是烟株矮小黄化的主要原因。此外,乙氧磺隆暴露导致烟株体内脯氨酸含量、超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量发生变化,这表明乙氧磺隆在烟株体内诱导了抗逆和抗氧化效应。乙氧磺隆在大田土壤中的残留消解符合一级动力学方程,其半衰期为16.5 d。[结论]根据乙氧磺隆的残留消解动态和致害阈值,推算乙氧磺隆在烟草作物上的使用安全间隔期约为69 d。可为烟-稻轮作区乙氧磺隆的正确使用和保障烟草生产安全提供帮助。

[Aims]The sulfonylurea herbicide ethoxysulfuron is widely used in tobacco-rice rotation areas in China.Correctly identifying the symptoms of ethoxysulfuron damage,clarifying the causes and thresholds of phytotoxicity,can help ensure the safety of tobacco production.[Methods]The field trials and indoor pot tests were used to study the phytotoxicity symptoms of tobacco caused by ethoxysulfuron residue.[Results]The results of field trials indicated that the residue of ethoxysulfuron could lead to yellowing and wrinkling of tobacco leaves,resulting in stunted tobacco plants.In severe cases,it could lead to tobacco withering and death.The pot test results showed that there was a dose-effect relationship between ethoxysulfuron residue and tobacco phytotoxicity.With the increase of the exposure dose of ethoxysulfuron,its inhibitory effect on the height and leaf area of tobacco gradually enhanced.On day 30 after application of ethoxysulfuron at 30μg/kg,the inhibition rate on the height and leaf area of tobacco was more than 10%.In the high-dose treatment group of ethoxysulfuron,the content of chlorophyll and indoleacetic acid(IAA)in tobacco leaves significantly reduced,while the content of abscisic acid(ABA)significantly increased,which might be the main reason for tobacco plant dwarfism and yellowing.Additionally,ethoxysulfuron exposure caused changes in proline content,superoxide dismutase(SOD)activity and malondialdehyde(MDA)content in tobaccos,suggesting that ethoxysulfuron induced stress resistance and antioxidant effects in tobacco plants.The residual dissipation of ethoxysulfuron in field soil followed the first-order kinetic equation,with a half-life of 16.5 d.[Conclusions]Based on the dissipation characteristic and damage threshold,the preharvest interval of ethoxysulfuron on tobacco was estimated to be 69 d.This study can provide assistance for the correct use of ethoxysulfuron in tobacco-rice rotation area and ensure the safety of tobacco production.