<p>Arbuscular mycorrhizal (AM) fungi change phosphorus (P) uptake and plant growth. The degree of change is defined as mycorrhizal dependency. Mycorrhizal dependency differs among cultivars and among different levels of soil P availability. The purpose of this study was to study the effect of AM fungus colonization on <i>Allium fistulosum</i> (<i>A. fistulosum</i>) with different mycorrhizal dependency grown at different levels of soil P availability. Twenty cultivars of <i>A. fistulosum</i> were grown with or without (control) AM fungus <i>Rhizophagus</i> spp. strain R-10 for 82 days. Three cultivars of <i>A. fistulosum</i> with different mycorrhizal dependency were inoculated and grown in soils fertilized at the rate of 0.43, 0.87, 2.18, and 4.36&#xa0;g P kg^-1 soil (P1, P2, P3, and P4, respectively) with or without (control) the AM fungus for 82 days. AM colonization, root length, shoot dry weight, and P concentration were determined. AM colonization increased shoot P content and shoot dry weight. Mycorrhizal dependencies were different among 20 cultivars and Mogamigawa, Shonan, and Kannonhosonegi were used as high, middle and low mycorrhizal dependency cultivars, respectively. Shoot P content of Mogamigawa and Shonan cultivars was higher in the inoculated plants than that in the uninoculated plants at P1, P2 and P3 soil fertilization rates. Shoot P content of the Kannonhoso was higher in the inoculated plants than that in the uninoculated plants at P1. Shoot dry weight of the Mogamigawa and Shonan was higher in the inoculated plant than that in the uninoculated plant at P1. These results suggest that selection of an appropriate cultivar and soil P availability are important factors in determining possible mutualistic, commensalistic, and parasitic relationships between the AM fungus and the host plant.</p>