Bean nodulation patterns in soils of different texture at Morogoro, Tanzania

Abstract

This study was designed to examine the, relationship between nodulation in a bean-Rhizobium system in three soils of varying texture and % recovery of rhizobia I cells immediately after inoculation into such soils. Effects of inoculation methods (seed pelleting versus soil inoculation) on nodulation and plant growth were investigated in the three soils using a serologically- marked Rhizobium strain (ClAT 899) which was subsequently monitored in the nodules by the enzyme-linked immunosorbent assay (ELISA) technique. When the major soil chemical factors affecting nodulation were standardized, bean nodulation patterns continued to be closely related to soil texture, being higher in the sandy and loamy soils than in the fine-textured clay. Soil inoculation consistently gave better nodulation than seed pelleting.According to the ELISA procedure however, percent nodule occupancy by ClAT 899 showed patterns completely the opposite of the nodulation trends outlined above, being 100% in the clay but only 10% in the sandy soil. Thus, nodulation success by the inoculum was total in the clay but only dismal in the sandy soil. The unexpected discrepancy between inoculum success on the one hand and nodulation plus plant growth response on the other, is discussed.