INFLUENCE OF SOIL-PH ON THE SOYBEAN-ENDOMYCORRHIZA SYMBIOSIS

Soybean (Glycine max {L.} Merr.) cultivars were inoculated with Gigaspora gigantea and Glomus mosseae to determine mycorrhizal: cultivar relationships as affected by soil pH. The specific cultivarfungal response was dependent on soil pH. Overall cultivar responses in unlimed soil (pH 5.1) were greater for G. gigantea than G. mosseae. The 'Bossier' -G. gigantea combination was particularly responsive in unlimed soil and showed an increase of 10% in shoot length, 35% in shoot dry weight. 75% in root dry weight, and 397% in nodule dry weight over uninoculated controls. Little cultivar response was observed with G. mosseae inoculation in unlimed soil. In limed soil (pH 6.2), the larger responses were obtained with G. mosseae inoculated plants, although inoculation with either G. mosseae or G. gigantea appeared effective. In general, nodulation was greater on mycorrhizal roots than on control roots. © 1979 Martinus Nijhoff Publishers.