RHIZOSPHERE MICROFLORA ASSOCIATED WITH MYCORRHIZAE OF DOUGLAS FIR

Abstract

Rhizosphere microflora of three morphologically different mycorrhizae of a Douglas-fir were examined and compared with microflora surrounding adjacent suberized roots and in non-rhizosphere soil. Populations of bacteria, molds, and Streptomyces were different for each microhabitat. Bacteria varied in total numbers and in distribution of morphological and physiological types. A low percentage of Streptomyces and fewer molds were found in mycorrhizal and adjacent suberized root rhizospheres than in the soil mass, Rhizosphere fungi were predominantly members of the genus Penicillium, which also were abundant in non-rhizosphere soil together with representatives of Aspergillus and Trichoderma, Rhizosphere differences between the morphologically distinct white, grey, and yellow mycorrhizae are attributed to the different associated fungal symbionts.