Effectiveness of Glomus species in protecting white clover against nematode damage

Abstract

Three species of arbuscular mycorrhizal (AM) fungi, Glomus aggregatum Schenck and Smith emend. Koske, Glomus intraradices Schenck and Smith, and Glomus mosseae (Nicol. and Gerd.) Gerdemann and Trappe, were evaluated for their effectiveness to suppress the plant parasitic nematode Meloidogyne incognita (Kofoid and White) Chitwood in white clover (Trifolium repens L.) in a greenhouse study. Forty 1-day-old seedlings not colonized or colonized to the same extent by the fungi were transplanted into a growth medium uninoculated or inoculated with 10 000 M. incognita eggs. After 40 days of further growth, root mass, shoot mass, extent of galling, number of nematodes and nematode eggs in roots, and extent of mycorrhizal colonization of roots were determined. Growth of white clover was significantly stimulated by mycorrhizal colonization, and nematodes caused the greatest damage when plants were not colonized by the fungi. The degree to which mycorrhizal fungi reduced nematode damage varied with the species of mycorrhizal fungus; the extent of damage reduction ranged from 19 to 49.8%, based on loss of shoot mass. The effectiveness of the mycorrhizal fungal species in suppressing nematodes was not related to the degree to which they colonized roots or their effectiveness in enhancing host growth.Key words: AM colonization, galls, Glomus aggregatum, Glomus intraradices, Glomus mosseae, inoculum potential, Meloidogyne incognita, nematode eggs, phosphorus.