我国稻区稗草对丁草胺抗药性现状

１９９１－１９９３年，对我国三大栽培类型稻区内９个监测网点的稗草抗药水平发展动态进行了系统的追踪监测。结果显示：我国稗草对丁草胺已产生了明显的抗药性。以ＬＣ５０和ＬＣ９０作为标准，最高抗性系数分别由１９９１年的２．９０和２．７９，上升至１９９３年的５．４２和１１．０４。在丁草胺连续使用８年以上地区，抗性水平呈急剧上升之势。稗草对丁草胺的抗性水平与连续使用时间呈正相关，而与ａ－淀粉酶活性抑制率呈反相

THE PRESENT SITUATION OF RESISTANCE OF THE BARNYARDGRASS TO BUTACHLOR IN THE RICE PLANTING AREAS IN CHINA

The resistance level of the barnyardgrass in 9 experimental localities within 3 rice planting areas of China has been systemacally monitored from 1991 to 1993. The results indicated that the barnyardgrass itself has already produced evident resistance to butachlor. If LC50 (Median lethal concentration) and LC90 are taken respectively as a standand density, when compared with susceptible strains, the maximun resistance factors have been increased accordingly from 2. 90 and 2. 79 in 1991 to 5. 42 and 11. 04 in 1993. In the areas where butachlor has been used repeatedly for 8 years, resistance level has already been brought into an rapidly increasing situation. While the resistance level of the barnyardgrass is directly proportional to the time of using butachlor. The experimental results showed that in Guangdong and Liaoning where butachlor has repeatedly been used for more than 10 years, the a-amylase activity was not inhibited, but evidently this function has been activized. This demonstrated that there happened physiochemi-cal changes in the resistant barnyardgrass.