Interactions between ectomycorrhizal fungi, plant-parasitic and free-living nematodes and their effects on seedlings of the hardwood Afzelia africana Sm.

Abstract

Summary Six ectomycorrhizal fungal strains (5 Scleroderma spp., one an unidentified strain) were inoculated and their effect on the growth of A. africana seedlings studied. The susceptibility of Afzelia africana was simultaneously tested against two plant parasitic nematodes (Tylenchorhynchus gladiolatus, Pratylenchus pseudopratensis). Over 8 months each pot was colonised by free-living nematodes. The effects of mycorrhizal and phytoparasitic nematode treatments on the density of the different taxa of free-living nematodes were studied. Each fungal isolate increased the plant growth but at different levels. When these fungi were inoculated together with one of the plant parasitic nematodes, the establishment of the mycorrhiza was decreased, but the presence of the phytoparasitic nematodes did not reduce the plant biomass. Generally A. africana was a good host for T. gladiolatus and a moderate for P. pseudopratensis. Most of the free-living nematodes that invaded the pots were bacterial feeders (Cephalobidae, Rhabditidae, Prismatolaimidae), fungal feeders (Aphelenchina) and omnivorous (Qudsianematidae). The density of free-living nematodes was greatest in most treatments where fungi were inoculated. Moreover, the structure of the nematode community was dependant of the fungal strain. One fungal isolate (DBM002) stimulated the development of the Qudsianematidae, whereas two other fungal strains (Ssp408, SD109) stimulated the developement of Cephalobidae and Aphelenchina simultaneously.