中文摘要：

为了解替代牧草对少花蒺藜草（Cenchrus pauciflorus Benth.）的竞争作用,测定了营养生长中期紫花苜蓿（Medicago sativa L.）根和茎叶水浸提液对少花蒺藜草种子萌发的化感效应。结果表明：紫花苜蓿2种浸提液各浓度对少花蒺藜草种子萌发均具有一定的化感作用,但作用强度和效应存在差异,其中紫花苜蓿茎叶浸提液对少花蒺藜草种子萌发的抑制作用强于根浸提液,以0.1g·mL^（-1）紫花苜蓿茎叶浸提液对种子萌发的抑制效果最强,发芽率仅为51.12%,比对照低了44%;发芽指数为16.37,比对照降低了35.37%;随着发芽时间的延长,同浓度浸提液对少花蒺藜草胚根的抑制作用大于胚芽;浸提液处理过的少花蒺藜草幼苗中丙二醛（MDA）含量均高于对照,且随着浸提液浓度的提高MDA含量增大。初步确定紫花苜蓿可作为替代控制法防控少花蒺藜草的备选植物。

英文摘要：

In order to reveal the competitive mechanism between the perennial leguminous pastures and field sandbur （Cenchrus pauciflorus）, alfalfa （Medicago sativa L） aqueous extract with different concentrations were used to this experiment on seed germination and seeding growth of field sandbur. The results showed that the allelopathy of different concentrations of aquatic extract from alfalfa had different effects on Cenchrus pauciflorus seeds＇ shoots and roots. The extracts from alfalfa stem and leaves had stronger allelopathic effects on seed germination and seeding growth of Cenchrus pauciflorus than extracts from alfalfa roots. Particularly, the effects on seed germination and seeding growth of Cenchrus pauciflorus was the most significant when the extract concentration was 0.1 g·mL-1 from Alfalfa shoots. Seed germination rate was only 51.12%, 44% less than the control. The seed germination index was only 16.37 and declined by 35.37% compared with control group. With germination time going, the inhibition effects on roots of Cenchrus pauciflorus were stronger than the effects on shoots. The Malondialdehyde content of Cenchrus pauciflorus seedlings treated with extract of were higher than the control, and the MAD contents increased with the increase of the extract concentration. Alfalfa shoots had strong allelopathic effects on cenchrus pauciflorus. It is determined preliminarily that alfalfa could be used as alternative plants to control Cenchrus pauciflorus spreading.