Occurence and host specificity of indigenous rhizobia from soils of S？o Paulo State, Brazil

the occurrence of rhizobial communities at four sites under natural vegetation and one site under pasture were examined. isolates of rhizobia originating from crotalaria (c. junceae), common bean (phaseolus vulgaris) and pigeon pea (cajanus cajan) were studied in relation to population density, host specificity and the interaction between rhizobial occurrence, climatic conditions and soil properties. ph values and potential acidity were the soil properties that most affected rhizobial occurrence. rhizobia from crotalaria and common bean were evaluated at four sites, and from pigeon pea, at five sites. common bean was the most specific legume, followed by peanuts, crotalaria and pigeon pea.