Host Plant Traits Associated with Estimates of Nodulation and Nitrogen Fixation in Common Bean

Field and greenhouse experiments were conducted to study the relationships among plant growth traits; ratios of dry weights among nodules, roots, and shoots; and traits associated with N 2 -fixation potential of common bean ( Phaseolus vulgaris L.). The dry weights of plant parts and the traits associated with N 2 -fixation differed among the 10 lines studied. A visual nodulation score used to evaluate N 2 -fixation potential was correlated positively with nodule dry weight, acetylene reduction (AR) value, root dry weight, and shoot dry weight for plants grown under both greenhouse and field conditions. AR values, nodule dry weight, and visual nodule scores of plants grown in the greenhouse were correlated positively with the respective figures obtained for field-grown plants. These methods of evaluation can be used to discriminate among lines for N 2 -fixation potential.