Differences of hyphal and soil phosphatase activities between mycorrhizal and non-mycorrhizal plants were less studied under drought-stressed (DS) conditions. In a pot experiment, fungal alkaline phosphatase (FALP), and succinate dehydrogenase (FSDH), soil phosphatase activity, both soil and plant P contents were compared in 6.5-month-old trifoliate orange (Poncirus trifoliata) seedlings under 80 days of DS with or without inoculations by arbuscular mycorrhizal fungi (AMF, Glomus diaphanum, Glomus mosseae or Glomus versiforme).