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.
