Plant Response to Mycorrhizal Fungi: Host, Endophyte, and Soil Effects

Abstract

AbstractInteractions and growth responses in soybean [Glycine max (L.) Merr.] and sorghum [Sorghum bicolor (L.) Moench] colonized by the vesicular‐arbuscular mycorrhizal (VAM) fungi [Glomus fasciculatum (Thaxt. sensu Gerd.) Gerd. and Trappe] or [Glomus mosseae (Nicol. & Gerd.) Gerd. and Trappe] as grown in three northern California soil types were investigated in a 2 by 2 by 3 factorial experiment. Growth and development of both symbiotic partners were significantly influenced by all three factors (host plant, endophyte, soil). Growth responses to VAM‐fungal colonization varied with soil type from −10 to 400%. Phosphorus concentrations increased significantly in all soybean and some sorghum plants relative to non‐VAM controls as a result of VAM‐fungal colonization. Shoot dry matter as percent of fresh weight increased significantly in only those VAM plants which had also experienced a significant growth enhancement. Root/shoot ratios of most VAM plants were lower than those of the controls. Changes in root/shoot ratios were inversely related to changes in dry weight. The results show that soil type, as well as the host‐endophyte combination, is a significant factor in modifying the VAM growth effect independently of mineral nutrient availability.