Effects of arbuscular mycorrhizal fungi on damage by Striga hermonthica on two contrasting cultivars of sorghum, Sorghum bicolor

The interaction between arbuscular mycorrhizal (AM) fungi and the root hemi-parasite Striga hermonthica was studied in two cultivars of sorghum that are tolerant and sensitive to Striga. In the absence of S. hermonthica, AM fungi increased biomass of both cultivars of sorghum. The beneficial mycorrhizal effect on plant biomass was larger aboveground than belowground with the largest effect being noted for grain production. In the absence of AM fungi, S. hermonthica reduced biomass of both cultivars of sorghum to different degrees. Arbuscular mycorrhizal fungi cancelled out damage by S. hermonthica in the tolerant but not in the sensitive cultivar. The results are discussed in the framework of integrated sorghum management. Such management includes breeding for resistance, which could have consequences for mycorrhizal colonization, and soil management, which could affect abundance and persistence of the mycorrhizal mycelium. (C) 2001 Elsevier Science B.V. All rights reserved.