Factors Affecting Spore Germination of the Vesicular-Arbuscular Mycorrhizal Fungus, Glomus Epigaeus

SUMMARY

Soil moisture, temperature, and—to a lesser degree—pH influenced germination of Glomus epigaeus spores, whereas levels of soil fertility and spore density had little or no effect. Maximum germination occurred in soil at moisture levels at or above field capacity, between 18 and 25 C and at pH 6–8. No germination occurred in autoclaved forest, dune, and agricultural soils or in gamma-irradiated or steamed Chehalis silt loam; however, 65–80% germination occurred in most nonsterile soils and in both autoclaved and nonsterilized kaolin and activated charcoal. Germination was similar in nonsterile Chehalis soil containing nonmycorrhizal, ectomycorrhizal, or vesicular-arbuscular (VA) mycorrhizal hosts, even Two other VA-mycorrhizal fungi, Glomus mosseae and Gigaspora gigantea, germinated readily in nonsterile soil as well. Optimum germination of spores seems closely related to conditions that are optimum for growth of many host plants.