Introduction. Arbuscular Mycorrhizal Fungi (AMF) can promote host growth
and, among other benefits, alleviate the stress produced by transplanting seedlings from the
nursery to the field. The objective of this work was to evaluate the effect of the amount of
AMF inoculum on growth of Hancornia speciosa (Mangaba tree). Materials and methods. A
greenhouse experiment was performed using a randomized experimental design in a factorial
arrangement of 3 × 3 corresponding to: two AMF (Gigaspora albida Schenck & Smith and
Glomus etunicatum Becker & Gerdeman) treatments plus one control with plants without
AMF three inoculum densities [(50, 100 and 300) spores per plant], with five replicates, in a
methyl bromide sterilized soil. Results. After 120 d, seedlings associated with G. albida had
greater height, shoot diameter and dry biomass of the aerial part and leaf area than those
associated with G. tunicatum, independent of inoculum density. G. etunicatum did not
influence growth of H. speciosa. Positive correlations occurred between plant growth parameters
and root colonization promoted by G. albida. Regression analysis showed interaction
between the inoculum density of G. albida and plant growth parameters. Discussion and
conclusion. Increments in growth of H. speciosa can be obtained with inoculation of
approximately 180 spores of G. albida per plant, which could reduce the necessary period of
time for the transplanting of seedlings from the nursery to the field.