02655naa a2200289 a 450000100080000000500110000800800410001902200140006010000210007424501550009526000090025052018120025965000240207165000090209565000120210465000120211665000290212865000170215765000230217465000140219765000090221165300090222065300240222970000210225370000160227477300750229015467982024-04-24       2000    bl uuuu     u00u1 u    #d  a0178-27621 aVARGAS, M. A. T.  aResponse of field-grown bean (Phaseolus vulgaris L.) to Rhizobium inoculation and nitrogen fertilization in two Cerrados soils.h[electronic resource]  c2000  aMost soils sown with field beans (Phaseolus vulgares L.) contain indigenous rhizobia which might interfere with the establishment of inoculated strains. As a consequence, the benefits of bean inoculation are usually questioned, and the use of N fertilizer is gradually becoming a common practice. The present study had the objective of evaluating the effectiveness of inoculation and N fertilization in field soil with (site 1) and without (site 2) a previous bean-cropping history. At site 1, which had a rhizobial population of 7x10 (2 elevado ao quadrado) cells g (-1) soil, inoculation had no effect on nodulation or yield, whereas at site 2 (&lt10 cells g (-1) soil) inoculation incresead nodulation, nodule occupancy by the inoculated strain and grain yield. N fertilizer decreased nodulation at both sites, but increased grain yield at site 1 but not at site 2, indicating that the response to inoculation and N fertilization depends on the cropping history. When bean was cultivated for the first time, indigenous populations of rhizobia were low and high yields were accomplished solely with seed inoculation, with no further response to N fertilizer. In contrast, previous cultivation of bean increases soil rhizobia, preventing nodule formation by inoculated strains, and N fertilizer may be necessary for maximum yields. A significant interaction effect between N fertilizer and inoculation was detected for serogroup distribution only at site 2, with N fertilizer decreasing nodule occupancy by the inoculated strain and increasing the occurence of indigenous strains. Consequently, although no benefits were obtained by the combination of inoculation and N fertilizer, this practice may be feasible with the selection of appropriate N-tolerant strains from the indigenous rhizobial population.  ainoculation methods  asoil  aCerrado  aFeijão  aFertilizante Nitrogenado  aInoculação  aPhaseolus Vulgaris  aRhizobium  aSolo  aBean  aNitrogen fertilizer1 aMENDES, I. de C.1 aHUNGRIA, M.  tBiology and Fertility of Soils, Heidelbergergv. 32, p. 228-233, 2000.