Abstract: The effects of different herbicides on alfalfa (Medicago sativa L.) yield and weed control were explored by applying herbicides at four different leaf stages. The results showed that haloxyfop-P-methyl could be safely mixed with imazethapyr,bentazone or bromoxynil octanoate without affecting the control effect on oat (Avena sativa L.);the control effect of imazethapyr against redroot pigweed (Amaranthus retroflexus L.) fresh weight was 30%~90%. The efficiency of herbicides depends on application time. Alfalfa yield was as high as 1666 kg·hm^-2,when Imazethapyr was applied at three-leaf growth stage;When bromoxynil octanoate was mixed with haloxyfop-P-methyl at five-leaf stage,and the alfalfa yield was as high as 1 656 kg·hm^-2. During the three to five-leaf stage,1 050 mL·hm^-2 imazethapyr + l 600 mL·hm^-2 haloxyfop-P-methy,or application of 600 mL·hm^-2 haloxyfop-P-methyl alone is recommended.

Key words: alfalfa, seedling stage, herbicide, yield, control effect

摘要： 本研究通过在紫花苜蓿（Medicagosativa L.）四个不同叶期施用除草剂，来探索不同除草剂对苜蓿产量和杂草防控效果的影响。结果表明：高效氟吡甲禾灵可以分别和咪唑乙烟酸、苯达松、辛酰溴苯腈安全混用，且不会显著降低对燕麦（Avena sativa L.）的防效；咪唑乙烟酸对反枝苋（Amaranthus retroflexus L.）的鲜重防效较好，为30%~90%。不同除草剂适宜施用时期不同，咪唑乙烟酸适宜在3叶期施用，苜蓿的产量高达1 666 kg·hm^-2；辛酰溴苯腈与高效氟吡甲禾灵在5叶期混用，苜蓿的产量高达1 656 kg·hm^-2。科尔沁沙地苜蓿苗期适宜化学除草方法为：针对禾本科与阔叶杂草并存地块，应在苜蓿3叶期，施用咪唑乙烟酸1 050 mL·hm^-2+高效氟吡甲禾灵600 mL·hm^-2；针对禾本科杂草为主的地块，应在苜蓿3~5叶期，单独施用高效氟吡甲禾灵600 mL·hm^-2。

关键词: 苜蓿, 苗期, 除草剂, 产量, 防效