ROLE OF CA2-JAPONICUM STRAIN-273 ATTACHMENT ABILITY AND ACCUMULATION ON SOYBEAN ROOT SURFACE( IN BRADYRHIZOBIUM)

Ca2+ limitation in the cultivation medium of Bradyrhizobium japonicum strain 273 and in Hellriegel's nutrient solution led to optimal bacter ial growth and to greater accumulation and attachment of the bacterium to the root hair surface. With the increase of Ca2+ in the medium the bacterial attachment ability and their quantity on the root surface w ere reduced. Optimal nodule formation in soybean plants required 127 m u M Ca2+ in the nutrient medium. The problem concerning differences be tween Bradyrhizobium japonicum and Rhizobium leguminosarum attachment and accumulation caused by Ca2+ is discussed.