In order to study the biological characteristics of Rhizobia in A. cincinnata,12 rhizobia strains were isolated from A. cincinnata stand in Gaofeng forest farm of Guangxi, southern China. The physio-biochemical characteristics of these strains were detected, and the isolated strains were also inoculated to the A. crassicarpa in order to study the formation of root rhizobia nodule. The results showed:(1)According to the growth rate, the 12 isolated strains could be divided into 9 fast-growing strains and 3 slow-growing strains. (2) Inorganic nitrogen (NH4++NH3-) could be utilized by most strains, but the utilization of sugar sources by strains shown diference. (3) In the experiments treated with 3-keto-lactose, beef-protein and tarch hydrolysis respectively, all of 12 tested strains shown negative response, while in B.T.B reaction and citrate utilization, the results shown positive response. In litmus milk experiment, all of strains produced alkai. (4) Inoculation of 12 isolated strains of A. cincinnata to A. crassicarpa could effectively stimulate the formation of rhizobia nodule in the fine root of A. crassicarpa. Based on the nodule size and nitrogen fixing enzymes activity, the strains of J003, J004, J005, J008 and J012 were identified as the better strains. It provided the scientific information to isolate and utilize the native rhizobia strains in southern China.
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