| The alfalfa is one kind of perennial leguminous forage with high economic value and nutritional value. The alfalfa can not only provide the high quality green protein feed for the domesticated fowl, but also improve soil and enhance the fertility, which is profoundly significant to the ecological environment. The effective method of increasing the alfalfa yield is the vaccination of the matching nodule bacteria on it. In the present study, the symbiotic of 7 strains of alfalfa rhizobia from Agricultural Culture Collection of China (ACCC) and 6 alfalfa varieties were investigated preliminarily and 7 Sinorhizobium meliloti were identified systemically by the reaction characteristic of the physiological biochemistry, the Biolog system of bacterim identification and the 16S rDNA sequential analysis method.Through nodulation experiments and effectiveness analysis of nodule bacterium and different alfalfa varieties in the non-nitrogen liquid medium, compared with the control, 6 rhizobia and 5 alfalfa varieties with better symbiotic matching effects were screened and 15 combinations were developed. The pot trial was conducted with these 15 combinations and the symbiotic nitrogen fixation growth effects of 5 alfalfa varieties vaccinated with 6 rhizobia were studied, and the rhizobia with the best symbiotic effect on ach alfalfa variety was selected and 5 combinations of the alfalfa nodule bacteria and the alfalfa variety with good symbiotic matching were screened, followed by field trial of the 5 combinations, which will be the foundation. of promoting the application of alfalfa nodule bacteria.The results were as following:1. The symbiotic matching experiment between 7 rhizobia and 6 alfalfa varieties were conducted by filter paper bridge culture method, in the non-nitrogen liquid medium culture and the differences between each matching combination and the control were compared. 15 combinations with better effect of symbiotic matching were screened.2. By the simulation of the field soil environment in pot trial, the symbiotic matching test between rhizobia and the alfalfa varieties was conducted with antiseptic soil, and the adaptability of screened rhizobia and alfalfa combination, nodulation ability and the efficiency of nitrogen fixation were studied. The results indicated that nodulation rate, nodule quantity, the plant height, the plant fresh weight and dry weight, the total nitrogen when rhizobium ACCC17674 vaccinated on the different alfalfa varieties were significantly increased, compared with control and significant differenced between ACCC17674 and the other strains were found. It is explained that ACCC17674 is a broad-spectrum strain. Finally, 5 combinations were screening respectively Algonquin, Golden Empress, Madrigal, HuaiYin and Baoding with ACCC17674 .3. A field plot trial was conducted with 5 screened good combinations. The results showed that nodulation rate, the plant height, branch number, the total nitrogen and yield were significantly increased and 3 combinations with good symbiotic matching were obtained, which had the potential of application in practical production.It is explained that ACCC17674 is a broad-spectrum strain. 4. In the physiological biochemistry characteristics reaction test of 7 rhizobia, strains ACCC17674 and ACCC17675 could grow with the pH value of 4.0-9.5 and 4.5% salt, and it suggested that in field application, the 2 strains could be adapted to the soil of with high pH value change and high salt content, with the good adaptability to environment and the higher tolerance.5. 7 Sinorhizobium meliloti identified by Biolog identification system and the 16S rDNA sequence analysis, the results were consistent with the traditional methods. Therefore, the advcanced analysis methods were more systematic and comprehensive on the basis of traditional methods in bacterial identification.
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