Distribution of Vesicular-Arbuscular Mycorrhizae in Plants Growing in a River Floodplain.

Abstract

To study the effects of river flooding on vesicular-arbuscular mycorrhizae (VAM), VAM infection of plants was examined at a fluvial bar in the middle reach of the Ohta River in Hiroshima Prefecture, Japan. Among 23 plant species belonging to 11 families collected in spring and early summer 1993, 17 species showed VAM with arbuscules. The relation between VAM infection and plants' growth stages was investigated in the annual legume Kummerowia striata. VAM infection was observed early in seedlings that had few leaves. Prolonged flooding in the 1993 summer season severely destroyed the vegetation in the study site. However, most of the plants survived the flooding, and those which germinated afterward showed VAM infection. Spores of VAM fungi were found not only in the soils of areas with good vegetation cover but also in the soils of gravelly areas without vegetation. However, spore density and infection level tended to be lower in severely eroded sites.