The Presence of Beneficial Organisms Associated to N and P Economy in the Rhizosphere of Native Vegetation in an Oligotrophic Savanna of Guárico State, Venezuela

Abstract

Background:In natural conditions, tropical plants are adapted to different ecological niches that can be associated to soil microorganisms which play a key role in nutrient cycling likeArbuscular mycorrhiza(AM), phosphate solubilizing bacteria (PSB) and/or nitrogen fixing rhizobia.Methods:We report a survey of the presence in a Trachypogon savanna located at Estación Experimental La Iguana (EELI) in Central Venezuela, of some beneficial plant-microorganism associations. In this savanna, plants present a high AM symbiosis affinity. The high mycorrhization and the presence of potential PSB suggest a synergic effect in plant P-uptake.Results:After screening the rhizospheres of 25 plant species from the zone, we could isolate a high proportion of potential PSB in relation to the total bacteria number from the rhizospheres ofCentrosema venosumandGalactia jussiaeana.Conclusion:Therefore, the presence of potential PSB in the rhizosphere of those species constitutes an important finding to discover novel biofertilizers for crop plants.