Direct observation of spores of vesicular-arbuscular mycorrhizal fungi growing on sugar maple roots in the field, using sodium hexametaphosphate as a soil dispersant

Abstract

A method for observing the extramatrical mycelium and attached spores of vesicular-arbuscular mycorrhizal fungi on the roots of plants recovered from the field is described. The method can be used to determine the species of vesicular-arbuscular mycorrhizal fungi that sporulate on the roots of plants in nature, and can also be used to examine the phenology of sporulation in a natural ecosystem. Data are provided from use of the method on sugar maple seedlings recovered from two deciduous forests, one near St. Hippolyte, Québec, and the other near Waterloo, Ontario. We have shown that, at St. Hippolyte, Glomm aggregatum, G. hoi, G. macrocarpum, and G. rubiforme form associations with sugar maples, and that the sporocarpic Glomus species, G. aggregatum and G. rubiforme, produced spores in the fall, whereas the other two species formed them throughout the growing season. Whereas sporulation was observed on nearly 50% of the plants from the acidic site at St. Hippolyte, no sporulation was observed at the Waterloo site.

Key Words:

• Acer saccharum
• deciduous forest
• direct observation
• sodium hexametaphosphate
• sporulation
• vesicular-arbuscular mycorrhiza