中文摘要：

通过二亲接合的方式，将含有sacB基因和nodD基因部分片段的质粒与中慢生华癸根瘤菌（Mesorhizobiumhuakuii）93（Mh93）菌株进行同源重组，在含10％蔗糖的TY平板上成功地筛选到了nodD基因突变株Mh93-27。利用温室盆栽试验研究了紫云英单作及紫云英．小麦间作体系Mh93-27对紫云英的促生作用，结果表明，接种Mh93．-7后，紫云英的地上部生物量和全氮含量以及根部生长得到了不同程度的提高，但只有在小麦孕穗期和收获期时，根瘤菌才表现出显著的促生作用。

英文摘要：

A nodD-strain of Mesorhizobium huakuii, Mh93-27 was obtained and the effect of PGPR on astragalus was studied in a single cropping of astragalus and the mixed cropping of astragalus-wheat. Homologous recombination between the plasmid with sacB gene and nodD gene segment and symbiotic plasmid of Mh93 through parental mating could take place, nodD gene could be deleted or cured on TY plate with 10% sucrose, thus the nodD-strain could be obtained. The pot-growing experiment showed that the biomass and nitrogen content of astragalus increased after being inoculated with the nodD-strain of Mh93,but the rhizobium showed obvious effect on astragalus only during the heading and harvest stages of wheat.