EFFECT OF SODIUM-CHLORIDE AND MANNITOL ON GERMINATION AND HYPHAL GROWTH OF THE VESICULAR-ARBUSCULAR MYCORRHIZAL FUNGUS GLOMUS-MOSSEAE

The effects of low osmotic potentials on the germination and hyphal growth of a vesicular-arouscular (V.A.) mycorrhizal fungus were examined. Surface sterilised chlamydospores of Glomus mosseae were plated on 1% water agar osmotically adjusted at six different levels with either NaCl or Mannitol. Little or no germination occurred below 0.75 MPa with the osmotoxicants used. Hyphal growth was more affected than germination by low water potentials and Mannitol was consistently more efficient than NaCl at inhibiting, both germination and hyphal growth. These results indicate the importance of low osmotic potentials as opposed to direct salt toxicity on the germination mechanisms. As salt toxicity and water availability are the two major plant stresses that occur in arid and semi arid ecosystems more research is being done to asses the behaviour of V.A. mycorrhizal fungi under these conditions. © 1990.