The leguminous tree Anadenanthera peregrina var. falcata (angico-do-cerrado) forms symbiotic associations with nitrogen fixing bacteria (rhizobia) and arbuscular mycorrhizal fungi. The aim of this study was the evaluation of the influence of rhizobial and arbuscular mycorrhizal inoculation on the initial growth of angico-do-cerrado plants, in autoclaved and non-autoclaved soil with and without inoculations. The experiment was carried out in a greenhouse using mycorrhized roots of maize and a mixture of rhizobial isolates as inocula. Plant growth was positively affected by dual inoculation of mycorrhizal fungus and rhizobia: plants of this treatment produced 60 % more biomass than in the control in the 10th month. Inoculation of only one microsymbiont, however, did not promote difference in plant growth. Mycorrhizal formation was significantly more extensive and the number of nodules higher in plants of non-autoclaved soil, caused by native soil borne fungi and rhizobia. In this treatment mass accumulation was lowest in the xylopodium, probably because of the photosynthetic drain caused by microsymbionts, and P concentrations in shoot and xylopodium were about 1.2 and 8 times higher in these plants, respectively, due to the mycorrhizal colonization.
angico-do-cerrado; rhizobia; arbuscular mycorrhizal fungi
