<p>One of the most promising techniques to promote seedling growth of tree species at nursery is the use of rhizosphere microorganisms. This is particularly relevant in enhancing plant performance in reforestation of degraded lands. A series of experiments were conducted to evaluate the effectiveness of either individual inoculation with the arbuscular mycorrhizal fungus Rhizoglomus fasciculatum (Thaxt.) Sieverding, Silva & Oehl or dual inoculation with R. fasciculatum and the phosphate solubilizing fungus Mortierella sp., at two doses (50 and 100 kg of inoculum per m3 of substrate), on plant growth and phosphorus (P) uptake of Tecoma stans, Dodonaea viscosa, Fraxinus chinensis, and Lafoensia speciosa. These plant species are commonly used in Colombia in reforestation programs. The results indicated that treatments were effective to increase plant performance of the four plant species; however, the effect was significantly higher when both fungi R. fasciculatum and Mortierella sp. were concomitantly inoculated than when only the mycorrhizal fungus was applied. Overall, the dual inoculation at the dose of 50 kg m-3 had higher or similar effects than at 100 kg m-3. The results suggest that the dual inoculation was more effective in order to prevent plant P deficiency and stimulate plant growth.</p>