This experiment aimed to determine effects of three arbuscular mycorrhizal fungi (AMF), i.e., Rhizophagus irregularis, Rhizophagus intraradices, and Funneliformis mosseae, either singly or their mix inoculation on dry mass, photosynthesis, chlorophyll (Chl) fluorescence, leaf pigment contents, and water-use efficiency (WUE) in Zinnia elegans (var. Magellan Red) plants under different water regimes (WR). The greenhouse experiment was performed under a complete randomized design at four different WR [100% of field capacity (FC) as control, 80, 60, and 40% FC]. Our results suggested that arbuscular mycorrhizal symbiosis protected zinnia plants against WR through improving gas-exchange capacity, higher Chl and carotenoid concentrations, Chl fluorescence, and WUE. Regardless of WR, comparison of colonization percentage demonstrated that the highest colonization was recorded for mixed AMF, while mixed inoculation was not so effective for the growth promotion as the corresponding single inoculation.