Effect of mycorrhizae on yield and disease suppression in onions and carrots
The arbuscular mycorrhizal (AMF) inoculant, Glomus intraradices Schenck and Sm. was evaluated to determine effects on yield and disease suppression in onions and carrots. Interactions with soil phosphorus (P) were also assessed. Trials were conducted on muck and mineral soils near Bradford, Ontario, Canada. There was no significant effect of AMF inoculant on AMF colonization in roots, except in roots of onions grown on muck soil. There was no significant effect of AMF and P on the yield of onions and carrots. Mycorrhizae reduced soil P content in carrot fields on muck soil. The severity of carrot leaf blights was lower in carrots grown from AMF-coated seeds. The AMF communities detected in roots varied with the crop. Higher soil P was associated with lower diversity of AMF in carrots, and application of AMF inoculant increased AMF diversity in onions. Application of AMF was not cost effective.