Application of Superphosphate to Mycorrhizal Plants Sitimulates Sporulation of Phosphorus‐tolerant Versicular‐arbuscular My Corrhizal Fungi *

SUMMARY Sporulation of Gigaspora margarita, Glomus clarum, Gl, mosseae and Gi. Heterogama was increased significantly after established pot cultures of bahiagras were drenched with superphosphate. However, sporulation of Gl. Etunicatum, Gl. Macrocarpum and Gi. Gigantean was reduced by the superphosphate drench. Generally, improved sporulation after application of superphosphate was associated with phosphorus (P)‐tolerance of the mycorrhizl fungi. Gigaspora margarita, Gl. Clarum and Gl. Mosseae could colonize roots in soil that had 199 mg kg −1 of acid‐extractable P. The other fungi could not colonize roots in this high‐P soil. Removal of shoots, application of herbicide, and stresses from drought and exposure to cold and dark did not affect spore numbers significantly.