Arbuscular mycorrhizal fungi (AMF) favours the growth and development of seedlings of various tree species, with consequent reduction in the use of chemical inputs. The present study aimed to evaluate the effect of nitrogen (N), phosphorus (P) and potassium (K) on diversity and sporulation of AMF species in the root colonisation (RC) of seedlings of Araucaria angustifolia. The experiments were performed using different doses of N (fixed P and K), P (fixed N and K) and K (fixed N and P) (mixed in pots whit historical soil from Araucaria angustifolia as substrate), with each having four treatments and four replicates. Seedlings were transplanted and two years after, the growth parameters, diversity and spore density, diversity indices (Shannon, Margalef’s richness and Pielou equity) and mycorrhizal colonisation were evaluated. A total of 14 species of AMF were identified on roots of Araucaria angustifolia species from the genus Glomus and Rhizophagus clarus, regardless of the doses of fertilisers used. P had the greatest effect on diversity of AMF species, since the average doses favour high RC and a greater number of AMF species.