Inhibition ofFusarium oxysporumf-sp.dianthiin the non-VAM speciesDianthus caryophyllusby co-culture withTagetes patulacompanion plants colonized byGlomus intraradices

摘要

The effect of the mycorrhizal fungusGlomus intraradiceson disease development caused byFusarium oxysporumf.sp.dianthiin the nonmycorrhizal speciesDianthus caryophylluswas studied by co-culture of carnation plants with the mycorrhizal speciesTagetes patula. Presence of VAMT.patulaplants more than doubled the survival ofD.caryophyllus, significantly reduced the disease symptoms, and decreasedF.o.dianthipropagules by 4:1 in soil. Non-VAMT.patulaplants had no effect.Dianthus caryophyllusshoot biomass was reduced byF.o.dianthiin non-VAM controls but was not affected in presence ofG.intraradices.Glomus intraradicesalone has no effect onT.patulaorD.caryophyllusshoot biomass.Dianthus caryophyllusmineral shoot content was not modified byG.intraradices. In absence ofT.patula,G.intraradicesdid not colonizeD.caryophyllus, whereas in its presence, 14ndash;20 of the carnation root length contained abundant vesicles and hypha but very rarely arbuscules. The presence ofG.intraradicesclearly reduced the disease caused byF.o.dianthiinD.caryophyllus. Reduction in disease severity was associated with reducedF.o.dianthipropagule number in the substrate and was clearly unrelated to plant nutrition. Our results may be explained either by the induction ofD.caryophyllusdisease resistance mechanisms by the mycorrhizal fungus or by direct or indirect microbial interactions in the soil.Key words: vesicularndash;arbuscular mycorrhizae, marigolds, carnation, disease, biocontrol.