Effectiveness of Rhizobium inoculation on common bean productivity as determined by inherent soil fertility status

Abstract

Field experiments at Haramaya, Hirna, Fedis, and Babillae sites were conducted to evaluate the effectiveness of selected isolates of rhizobia on the common bean production using eight selected isolates of rhizobia with a control check and N fertilized (20 kg N ha-1) treatments. The treatment was laid out in a randomized complete block design with three replications and three common bean varieties (Kufanzik, Gofta, and Dursitu).Analysis of variance revealed that inoculation, common bean varieties and their interaction significantly influenced most of the investigated yield and yield traits of common bean. Most of the tested Rhizobium isolates significantly increased the nodule number (NN) and nodule dry weight (NDW) as compared to the control check. Of the tested isolates, a higher number remarkably improved the remaining investigated traits in Hirna and Haramaya sites when compared to the Fedis and Babillae sites. In the Babillae site, N fertilization resulted in the highest NDW, total biomass yield (TBY), and grain yield (GY) of common bean. The GY increases due to inoculation of NSCBR-14 at Haramaya and Hirna sites, N fertilization at Babillae and NSCBR-31 at the Fedis site were 775.5, 609.7, 506.3, and 400.9 kg ha-1 over the uninoculated treatments of the corresponding experimental sites, respectively. The highest NN, NDW, and plant N concentration was recorded with Dursitu while the highest GY and TBY were obtained from Kufanzik. Therefore, inherent soil fertility and the prevailed environmental factors affect the effectiveness of the inoculated isolates in enhancing common bean production in the study sites.