Proliferation of inoculatedRhizobiumand indigenous microbes around the periphery of pre-rooting common beanPhaseolus vulgarisL. seeds sown in non-sterile soils

Abstract

The proliferation of inoculated gusA-marked (encoding β-glucuronidase) Rhizobium and indigenous microbes around the periphery of common bean (Phaseolus vulgaris L. cv. Hokkaikintoki, Himetebou and Kurodanekinugasa) seeds sown in non-sterile Japanese soils (Andosol, Gray Lowland soil and Sandy Regosol) were investigated. The number of gusA-marked Rhizobium cells inoculated increased 24 h after sowing. The population of gusA-marked Rhizobium and indigenous bacteria tended to be smaller around seeds of Hokkaikintoki compared with the other cultivars. The population of gusA-marked Rhizobium and indigenous bacteria also tended to be smaller in Andosol than in the other soils. The proliferative response of indigenous fungi was weaker than that of gusA-marked Rhizobium or indigenous bacteria. These results indicated that Rhizobium inoculated around the periphery of common bean seeds could proliferate efficiently under the existence of indigenous microbes and that the intensity of proliferation was influenced by the type of common bean cultivar and soil type.