Abstract A pot experiment was conducted under two soil conditions, namely (i) Original paddy soil and (ii) Diluted soil (paddy soil diluted with andosol subsoil; Paddy soil: Andosol subsoil=1:4) to investigate the effects of arbuscular mycorrhizal fungi (AMF) and water regimes on dry matter production, grain yield, AMF colonization, AMF sporulation, and mineral nutrition of wetland rice (Oryza sativa L.). Plants were either inoculated ( + AMF) or not (-AMF) under four water regimes, namely (i) Flooded up to maturity (F); (ii) Non-flooded (kept at 60% moisture of maximum water holding capacity) up to maturity (NF); (iii) Flooded for 3 weeks after sowing and then non-flooded up to maturity (F-NF); and (iv) Non-flooded for 3 weeks after sowing and then flooded up to maturity (NF-F). There were 2×2×4=16 treatment combinations. Generally, plants grown in paddy soil showed a higher plant dry matter content and higher N, P, K concentrations than in diluted soil. Grain yield was higher and grain formation was imp...