Abstract
A field experiment was conducted to evaluate the effect of Rhizobium inoculation methods and the effect of different levels of N fertilization on nodulation, nitrogen fixation and yield of Phaseolus vulgaris L. The N treatment produced a seed yield significantly higher than that of the other treatments. Inoculation treatments had no significant effect on nodule number and dry weight, even when compared to the noninoculated and N controls. This finding was attributed to a high number of Rhizobium phaseoli in the soil. The applications of N and inoculation did not significantly affect the N percentages of foliage and grain or nitrogenase activity. Serological identification of nodules indicated that the native strain UPRM 6000 farmed the largest percentage of nodules (41%), followed by R. phaseoli 127K44 (34%), 127K17 (13%) and 127K12b (10%). The serogroup distributions of inoculated and N fertilized treatments differed significantly from the noninoculated control. Inoculation methods (seed vs. soil) did not differ significantly in either nodulation or yield responses.