TESTING A DIFFERENTIAL SET OF ANDEAN AND MESOAMERICAN COMMON BEAN GENOTYPES TO CHARACTERIZE \u3ci\u3eRHIZOBIUM\u3c/i\u3e ISOLATES

INTRODUCTION Nitrogen (N) deficiency is present in common bean (Phaseolus vulgaris L.) fields in most production regions in Central America and the Caribbean (CA/C), especially on small hillside farms where no or sub-optimum levels of fertilizer are used. Under these conditions, Rhizobium inoculants could represent a cheap and effective input to increase bean yield. Despite the potential benefits from increased biological nitrogen fixation, Rhizobium inoculation is rarely used by farmers in CA/C. Nodulation and nitrogen fixation (N2) of bean cultivars in response to Rhizobium inoculation is quite variable due to several biological and edaphic factors (Graham et al. 2003). On the other hand, the response of different bean cultivars and germplasm accessions to different Rhizobium species and strains that nodulate and fix N2 is often difficult to measure on farms. A better understanding of specific bean host-plant-Rhizobium strain interactions would facilitate the selection of superior symbionts with greater response to inoculation and increase bean productivity in N-limited soil