Seeds of Gmelina arborea at three different maturity degrees were inoculated with Glomus manihotis, Glomus occultum and Azospirillum brasilense immobilized in alginate microbeads. Inoculated seeds were sown in two different growing systems: soil and compacted| peat-Jiffy®. Forty-one days after sowing (das), the effects of growing system and microorganism application on seed germination were determined. Forty-seven das, mycorrhization percentages and plant height were evaluated. Results showed that the growing system and the inoculation of A. brasilense have a significant effect (p<0.01) on the germination of G. arborea seeds. A positive correlation between mycorrhization and plant height was found during the initial stage of establishment in greenhouse conditions (0.61 p=0.03). In addition, there is a synergic effect of both types of microorganisms on mycorrhization.