Abstract: The Petri dish culture method was used to investigate the effects of coumarin,caffeic acid and its mixture on the growth of the root,the activity of root border cells and root cap pectin methyl esterase (PME) of alfalfa. The results showed that Coumarin and caffeic acid had obviously low concentration promoting effect and high concentration inhibition effect on the elongation of roots and the activity of root border cells of alfalfa,and the inhibition effect was significantly enhanced with the increase of treatment concentration. When the treatment concentration was 0.5 mg·L^-1 and below,the promoting effects of mixture treatment was the strongest,followed by caffeic acid and coumarin,and the inhibitory effects of coumarin treatment was the strongest,followed by mixture and coffee acid,when the treatment concentration was 50~500 mg·L^-1. Five mg·L^-1 of coumarin and mixture treated alfalfa,gave the highest root cap pectin methyl esterase(PME) activity. Compared with the control,it was significantly increased by 42.74% and 48.39%,respectively (P<0.05). In conclusion,synthesis allelopathic inhibition effects of coumarin,caffeic acid and mixture were:coumarin > mixture > caffeic acid.

Key words: Coumarin, Caffeic acid, Alfalfa, Root border cells

摘要： 采用培养皿培养法研究了香豆素、咖啡酸及其混合物对紫花苜蓿（Medicago sativa L.）根尖生长、根缘细胞活性和根冠果胶甲基酶的影响。结果表明：香豆素和咖啡酸对苜蓿根系伸长生长、根缘细胞活性有明显的低浓度促进高浓度抑制效应，随着处理浓度的增加抑制效应显著增强，0.5 mg·L^-1及以下低浓度处理时，混合物处理的促进作用最强，咖啡酸次之，香豆素最弱，50～500 mg·L^-1高浓度处理时，香豆素处理的抑制作用最强，混合物处理次之，咖啡酸最弱。5 mg·L^-1浓度的香豆素和混合物处理紫花苜蓿，其根冠PME活性最高，较对照分别提高了42.74%和48.39%，差异显著（P<0.05）。香豆素、咖啡酸和混合物的综合化感抑制效应表现为：香豆素 > 混合物 > 咖啡酸。

关键词: 香豆素, 咖啡酸, 紫花苜蓿, 根缘细胞