中文摘要：

Soil pH is a main factor that affects the nodule formation and nitrogen fixation. The largely reduced nitrogen fixation effect caused by acid soil is the major limitation of alfalfa growth in the south of China. Thus selection of anti-acid nodule for inoculating on alfalfa is of great significance in practical production.Using nine candidate rhizobia( Rhizobium meliloti L.) as study objects,their colony diameters and the nodule number of each strain inoculated alfalfa variety were investigated at different pH conditions. The YNCY006 strain presented the strongest resistance to acid,while YNCY007 strain presented the weakest. For nodulation,GT13 R alfalfa inoculated with YNCY006 or YNCY008 strains was the best symbiosis system in the acidic soil.

英文摘要：

Soil pH is a main factor that affects the nodule formation and nitrogen fixation. The largely reduced nitrogen fixation effect caused by acid soil is the ma- jor limitation of alfalfa growth in the south of China. Thus selection of anti-acid nodule for inoculating on alfalfa is of great significance in practical production. Using nine candidate rhizobia （ Rhizobium meliloti L. ） as study objects, their colony diameters and the nodule number of each strain inoculated alfalfa variety were investigated at different pH conditions. The YNCY006 strain presented the strongest resistance to acid, while YNCY007 strain presented the weakest. For nedulation, GT13R alfalfa inoculated with YNCY006 or YNCY008 strains was the best symbiosis system in the acidic soil.