Abstract:For scientifically evaluating the halosulfuron-methyl security to maize, the tolerance and mechanism of different maize varieties to halosulfuron-methyl were determined using pot-culture method and enzyme assay in laboratory. The result demonstrated that different maize varieties had different tolerance to halosulfuron-methyl, Tianyumi had the lowest tolerance with IC10 value 94.87 g/hm2(effective constituent, the following is the same), the medium tolerance ratio of Huanuo 1, Ludan 981, Wuyue 97-1 et al, are between 1.51 and 1.97, and Wuyue 21, Zhengdan 958, and Qiangsheng 16 showed the higher tolerance with the tolerance ratio 2.05-2.43. The tolerant variety Qiangsheng 16, the medium tolerant variety Ludan 981 and the sensitive variety Tianyumi were chosen for enzyme assay. The sensitivity of the three tested varieties in vitro to halosulfuron-methyl was not significantly different, even though the difference in tolerance between the three tested varieties was significant. The ALS in vivo activity of the three ones could renew rapidly, while the tolerable variety had a stronger recovery capability. The GSTs activity of Qiangsheng 16 being dealt with halosulfuron-methyl showed a rapider and larger amplitude response to halosulfuron-methyl than Tianyumi after being treated by halosulfuron-methyl. The relative GSTs activity of Qiangsheng 16 reached the peak value 4.2 in 72 h but that of Tianyumi reached the peak value 2.6 in 96 h. The mechanism of various maize varieties showed different tolerance to halosulfuron-methyl didn‘t related with the sensitivity of ALS, but with the enhancement of maize‘s GSTs activity.