两种稻田用除草剂残留对烟草危害的阈值研究

为指导烟稻轮作区稻田用除草剂2，4-滴丁酯和氯氟吡氧乙酸的合理使用，通过室内盆栽与大田试验，研究了两种除草剂在土壤和烟株中的残留和消解动态，以及烟株药害症状和内源激素含量变化。结果表明：（1）两种除草剂残留均可导致烟株矮化，茎秆扭曲，烟叶卷曲黄化；（2）两种除草剂残留导致不同部位烟叶IAA和GA₃含量显著降低，ABA含量显著升高（p<0.05）；（3）随施用剂量和处理时间增加，两种除草剂残留对烟株农艺性状的抑制作用增强，以株高或叶面积抑制率为10%~15%为标准，2，4-滴丁酯和氯氟吡氧乙酸的致害阈值在土壤中分别为1.022和0.053 mg/kg，在叶片中分别为0.047 8和0.027 6 mg/kg；（4）结合致害阈值得出2，4-滴丁酯和氯氟吡氧乙酸的田间安全间隔期分别为53 d和160 d。

Study on Tobacco Phytotoxicity Thresholds Caused by Residues of Two Herbicides Used in Paddy Fields

In order to guide the rational use of 2,4-D butyl ester and fluroxypyr in paddy fields in tobacco-rice rotation areas, the residues and digestion dynamics of the two herbicides in soil and tobacco, tobacco plant phytotoxicity symptoms and endogenous hormone content changes were studied by indoor pot experiment and field experiment. The results showed that:(1) The residues of two herbicides could lead to dwarfing of tobacco plants, serious contortion of stems, curling and yellowing of tobacco leaves. (2) The residues of two herbicides significantly decreased the contents of IAA and GA₃, and significantly increased the content of ABA in tobacco (p<0.05). (3) With the increase of application dose and treatment time, the inhibition effect on agronomic traits of tobacco plants was enhanced. Taking the inhibition rate of 10%-15% for plant height or leaf area as the standard, the critical thresholds of 2,4-D butyl ester and fluroxypyr in soil were 1.022 mg/kg and 0.053 mg/kg, respectively, and the critical thresholds in leaves were 0.047 8 mg/kg and 0.027 6 mg/kg, respectively. (4) Combined with the critical threshold, the safety intervals of 2,4-D butyl ester and fluroxypyr in the field were estimated to be 53 days and 160 days, respectively.