| Herbicide resistance is a worldwide phenomenon with the development of the chemical herbicides'application in agriculture, and it becomes more serious. Tribenuron-methyl is one of the most popular ALS inhibitor in wheat field with low price, high efficacy and good safety. After being applied over 20 years, some farmers complained that the flixweed (Descurainia sophia), one of the most important and widely infested broad leaved weeds in wheat fields was not sensitive to tribenuron-methyl any more which was registered in China in 1988. It is very important and necessary to confirm flixweed resistance and its mechanism to tribenuron-methyl in order to control flixweed effectively and use tribenuron-methyl in a scientific, rational way and to prolong the lifespan of tribenuron-methyl in practice. Flixweed seeds were collected from separate wheat fields that had been treated with tribenuron-methyl repeatedly over 3-15 years, and from road sides, remote hills that never received tribenuron-methyl treatment in Beijing and Tianjin Metropolitans, Hebei, Henan, Shandong, Shanxi, Shaanxi, Gansu, Qianghai, Jiangsu and Sichuan provinces with various herbicide application histories. Flixweed sensitivity to tribenuron-methyl was determined by whole plant experiments in the greenhouse, its resistant level and molecular mechanism were also conducted. The results showed as followings.1. Results of whole plant experiments showed that 42 of the 91 flixweed populations were susceptible to tribenuron-methyl with resistance indices ranging from 0.10 to 0.12g a.i./ha, 19 of the 91 populations expressed low level resistance to tribenuron-methyl with resistance indices ranging in 1 |
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