一切豆科作物的产量在某种程度上决定于在它们根上根瘤的发育情况和其中根瘤菌的固氮活动力。根瘤菌的固氮活动力依许多因素而定,只有在一定的条件下才能达到最大值。如果土壤中比较缺少植物能吸牧的氮素化合物,而在根瘤中含有活跃的根瘤菌小种,那么对大气氮的 The yield of all leguminous crops depends to some extent on the development of nodules on their roots and the nitrogen-fixing activity of rhizobia. Rhizobium nitrogen fixation activity depends on many factors, only under certain conditions to reach the maximum. If the soil is relatively lacking in nitrogen-absorbing compounds that can be grazed by the plant, and in the nodules contain active rhizobial races, then the atmospheric nitrogen