and 16 ESG strains from 18.2-39.6 hr and their pH of 7.57- 8.08.The three groups of soybean rhizobia varied in their growth rate and pH after the carbon source was replaced,but their generation times were still within devided range.

• 改变碳源对代时有影响，但仍在各自的代时范围内，证明世代时间是大豆根瘤菌菌株间比较稳定的重要表型特征之一；