Effect of inoculating selected climbing bean cultivars with different rhizobia strains on nitrogen fixation

Abstract

Experiments were designed to investigate biological nitrogen fixation in indeterminate (climbing) bean cultivars namely Cargamanto, NG224-4 and G59/1-2. Greenhouse and field studies were carried out to determine the most efficient bean cultivars and rhizobia strains in nitrogen fixation. Each cultivar was inoculated with the rhizobia strains CIAT 899, USDA 2674, USDA 2676, the three strains combined and one was not inoculated. There were no statistical differences in nodulation between the different inoculant treatments but in the field, beans inoculated with rhizobia strain USDA 2676 formed the highest nodule number. The bean cultivars inoculated with a mixture of the three rhizobia strains gave the highest total plant dry weight. Treatments within each of the cultivars showed differences in total plant dry weight yield in response to rhizobia strain used. Field experiments showed that plant dry weight differed significantly between cultivars but there were no significant differences in yields.

Keywords: Climbing beans, rhizobium, nitrogen fixation, inoculation, Central Kenya.