Effect of fungicides on vesicular-arbuscular mycorrhizal infection and nodulation in groundnut ( Arachis hypogea L.)

Abstract

The effects of field application rates of six fungicides (Bavistin, Dithane, Emisan, Fytolan, Thiram and Ziram), applied both as seed dress and soil drench, on the formation and function of vesicular-arbuscular mycorrhizal (VAM) and rhizobial nodular systems in groundnut ( Arachis hypogea L.) were investigated. Fytolan treatment produced a remarkable range of positive responses in VAM infection and spore production, rhizobial nodulation and growth and yield of the host plant. The other fungicides restricted mycorrhizal infection to different levels. The rhizosphere spore count was increased in the early growth stages of the host by fungicides, but declined in the later stages. Their effect on sporulation varied depending on VAM fungal species. Root nodulation, growth and yield of the host plant were not significantly affected by the application of fungicides, excepting the interference of Emisan in the early growth stages. The inhibitory effects of Emisan on the VAM and Rhizobium colonisation resulted in a significant decrease in the growth and yield of the host plant.