Abstract: Nicosulfuron-Atrazine is widely used to control annual and perennial gramineous weeds in maize fieldsbut may be harmful to alfalfa. To determine the effects of Nicosulfuron-Atrazine on seedling growth and yield of alfalfa,the herbicide dose was set as normal,medium,low and control dose,spray after sowing and before seedling. The results showed that the herbicide has a significant effect on alfalfa,which delayed the seedling of alfalfa for 8 days. The relative seedling rate of low doses,medium doses and normal doses of herbicide treatment was only 13.12%,4.86% and 2.93% of the control,respectively. There was no significant difference in the number of basal branches at 77d,although the fresh weight per plant was significantly increased to 256.28%,229% and 221.21% of the control,respectively,the number of seedings per unit area was only 13.73%,5.11% and 3.30% of the control. Therefore,the dry weight per unit area is only 36.16%,11.81% and 7.58% of the control. The above results showed that the herbicide is harmful to the seedling and growth of alfalfa.

Key words: Maize herbicide, Preemergence treatment, Alfalfa, Seedling rate, Above-ground dry weight

摘要： 为明确广泛应用于玉米田中防除一年生和多年生禾本科杂草的烟嘧磺隆·莠去津除草剂对紫花苜蓿是否具有药害，将除草剂剂量设为正常、中等、低等和对照四种剂量，在播后出苗前进行喷施，探讨了不同剂量的玉米除草剂对紫花苜蓿的出苗、生长及产量的影响。结果表明：该除草剂造成出苗时间推迟8 d，低等剂量、中等剂量与正常剂量除草剂处理相对出苗率分别只有对照的13.12%，4.86%和2.93%；生长至77 d，虽然单株鲜重比对照显著增加，但由于单位面积株数为对照的13.73%，5.11%和3.30%，因此，单位面积地上干重只有对照的36.16%，11.81%和7.58%。上述结果表明，该除草剂对紫花苜蓿出苗和生长等具有显著药害。

关键词: 玉米除草剂, 苗前处理, 紫花苜蓿, 出苗率, 地上干重