INTERACTIONS BETWEEN GLOMUS-MOSSEAE AND ARBUSCULAR MYCORRHIZAL SPOROCARP-ASSOCIATED SAPROPHYTIC FUNGI

The saprophytic fungi Wardomyces inflatus (Marchal) Hennebert, Paecilo myces farinosus (Holm & Gray) A. H. S. Brown & G. Sm., Gliocladium ros eum Bain., sterile dark mycelium (SDM-54), Trichoderma pseudokoningii Rifai and Trichoderma harzianum Rifai were isolated from sporocarps of Glomus mosseae. The effect of saprophytic fungi on G. mosseae spore g ermination was tested on water agar. Wardomyces inflatus decreased the percent germination of G. mosseae spores; G. roseum, T. pseudokoningi i and T. harzianum had no effect on germination; and P. farinosus and SDM-54 increased the percentage of spore germination of G. mosseae aft er 4 d. Wardomyces inflatus significantly decreased hyphal length of s pores which germinated: but no other saprophytic fungi affected hyphal growth. Trichoderma pseudokoningii, T: harzianum, Il farinosus and SD M-54 increased the number of auxiliary cells formed by G. mosseae. The effect of saprophytic fungi on arbuscular mycorrhizal colonization of soybean was studied in a greenhouse trial. The percentage of soybean root length colonized was decreased by W. inflatus, unaffected by SDM- 54 and T. harzianum, and increased by P. farinosus. Gliocladium roseum decreased root length colonized when plants were 12 wk old, and T. ps eudokoningii increased colonization of roots when plants were 4 wk old . Antagonistic, synergistic and neutral actions of G.. mosseae upon th e saprophytic fungi were observed. The population of T. harzianum decr eased and the populations of T. pseudokoningii and SDM-54 increased in the presence of G. mosseae. Our results indicate a complex interactio n between G. mosseae and associated saprophytic fungi.