中文摘要：

黄花棘豆属豆科棘豆属多年生草本植物,是我国西部草场广泛分布的主要毒草之一,为了探索黄花棘豆的危害机制,揭示其发生发展规律,本研究通过模拟黄花棘豆在土壤中的腐解过程,检测其对紫花苜蓿和黑麦草两种牧草的化感作用。结果显示当土壤中含有质量分数为5%的黄花棘豆时,黄花棘豆在腐解过程中就会对两种牧草的生长产生显著的化感抑制作用,其中对紫花苜蓿的化感作用更为明显。同时通过细菌16SrDNA测序对黄花棘豆根系土和非根系土中的细菌群落进行了比较,结果显示土壤细菌群落中的部分分类单元,如变形菌门（Proteobacteria）、放线菌门（Actinobacteria）和酸杆菌门（Acidobacteria）的比例在两组中存在显著差异;同时,非根系土的细菌群落多样性高于根系土。以上结果相结合表明黄花棘豆可能通过化感作用改变其生长土壤的微生物环境,在促进自身生长的同时降低不良微生物对其自身的影响,并抑制其他共生植物生长。本研究为更好地寻找黄花棘豆的有效防控提供了一定理论依据。

英文摘要：

Oxytropis ochrocephala ,a toxic perennial legume grass,is widely distributed across the grasslands of western China.Developing effective control methods for O.ochrocephala requires exploration of mechanisms contributing to its occurrence.Allelopathy is considered to be an underlying mechanism driving biological invasion in many plant species.In this study,the allelopathic effect of O.ochrocephala on the growth of Medicago sativa and Lolium perenne was analyzed,and the soil bacterial community from the rhizosphere and non-rhizosphere soils of O.ochrocephala were compared to examine if the plants exert allelopathy by altering soil bacterial communities.We planted Medicago sativa and Lolium perenne with soil containing different con-centrations of O.ochrocephala tissue powder.After growing for 60 d,plant height,biomass and chlorophyll content were measured.The results showed strong allelopathic effects on the growth of the two grass species with soil containing 5% O.ochrocephala tissue powder,in which plant height,biomass and chlorophyll content were significantly reduced.We compared the bacterial structure of O.ochrocephala rhizosphere and non-rhizosphere soils with 16S rDNA sequencing.The data showed that the structure of the bacterial communities differed greatly and the percentage of some phyla,such as Proteobacteria,Actinobacteria and Acidobacteria, were significantly different.In addition,there were more OTUs （Operational Taxonomic Units）in the non-rhizosphere soil.Since bacteria from different phyla are considered to function discriminately,these changes mean it is highly likely that O.ochrocephala implements allelopathy by altering the structure of the rhizospere bacterial community,and accordingly promotes its growth and competes with other associated plants.These results will assist the development of controlling strategies for O.ochrocephala in the future.