Seasonal changes of arbuscular mycorrhizal fungi as affected by tillage practices and fertilization: hyphal density and mycorrhizal root colonization.

摘要

A study was made in 1992-93 of the effect of tillage practices on native arbuscular mycorrhizal fungi (AMF) in 11-year-old tillage/fertilizer experiments on a sandy loam and a clay soil at Ste-Anne-de-Bellevue, Quebec, Canada, with maize cv. Funk 4120 grown in monoculture. The 3 tillage practices were conventional tillage (CT; autumn ploughing plus spring discing), reduced tillage (RT; spring discing) and no-tillage (NT). Maize was given either inorganic (N and K) or organic (liquid cattle manure)fertilizers. Densities of total and metabolically active soil hyphae, and mycorrhizal root colonization were significantly lower in CT soil than in RT or NT soil. Lowest soil hyphal densities were observed in early spring. The levels of intra- and extraradical fungal colonization increased from spring to silking and decreased thereafter. Spring discing had only a small and transient negative effect on hyphal abundance in soil. Fertilizers did not influence mycorrhizal colonization of maize or abundanceof soil hyphae in the sandy loam soil, but in the clay soil metabolically active hyphae were more abundant with manure application than with mineral fertilization. In 1992 grain yield did not differ between tillage systems, but in 1993 yield was highestin NT and lowest in CT.