INTERACTIONS BETWEEN TRICHODERMA-KONINGII, FUSARIUM-SOLANI AND GLOMUS-MOSSEAE - EFFECTS ON PLANT-GROWTH, ARBUSCULAR MYCORRHIZAS AND THE SAPROPHYTE INOCULANTS

The effect of inoculation with the saprophytic fungi Trichoderma koningii and Fusarium solani on maize (Zea mays) and lettuce (Lactuca sativa) with or without arbuscular mycorrhizal (AM) colonization by Glomus mosseae was studied in a greenhouse trial. Plant dry wt of non-AM inoculated maize and lettuce were unaffected by the presence of T. koningii and F. solani. In contrast, T. koningii decreased plant dry wt and AM colonization when inoculated into the rhizosphere before or at the same time as G. mosseae. In addition, the T. koningii population was considerably reduced when G. mosseae was inoculated 2 weeks before the saprophytic fungus. At this time T. koningii did not affect the proportion of the root length colonized by G. mosseae, but did adversely affect its metabolic activity assessed as succinate dehydrogenase activity. Although F. solani did not affect AM colonization of maize roots, its effect on AM colonization of lettuce roots was similar to that of T. koningii. The population of F. solani decreased significantly in the rhizosphere of both plants. The possible mechanisms of interaction between the saprophytic fungi and G. mosseae are discussed.