INVITRO INTERACTIONS BETWEEN THE VESICULAR ARBUSCULAR MYCORRHIZAL FUNGUS GLOMUS-MOSSEAE AND SOME SAPROPHYTIC FUNGI ISOLATED FROM ORGANIC SUBSTRATES

Six saprophytic fungi belonging to different genera and isolated from three organic substrates were tested under controlled in vitro conditions for their effect on the germination of Glomus mosseae (Nicol. & Gerd.) Gerd. & Trappe resting spores and on the development of vesicular-arbuscular mycorrhizal fungal (VAMF) mycelium. The development of G. mosseae was stimulated by sterile water extracts from organic substrates and by the presence of Trichoderma spp isolated from these substrates. Microbial inoculation did not affect the percentage of spore germination, which reached 90-95% after 26 days' incubation, but the germination rate was hastened and the development of VAM mycelium from germinated spores was enhanced by the presence of Trichoderma spp. Stimulation caused by Trichoderma might be attributed to the production of volatile compounds more than to non-volatile compounds released to the growing media. No hyphal contact between both types of fungi was necessary to detect stimulation in dual inoculation treatments. The other saprophytes tested inhibited spore germination.