title: Symbiotic Efficiency of Native Rhizobia Nodulating Common Bean (Phaseolus vulgaris L.) in Soils of Western Kenya.
abstract: This study was conducted to determine the abundance and symbiotic efficiency of native rhizobia nodulating common bean in Kisumu and Kakamega, Kenya. Soil sampling was carried out in three farms that had been used for growing common bean for at least two seasons and one fallow land with no known history of growing common bean or inoculation. Abundance of soil rhizobia and symbiotic efficiency (SE) were determined in a greenhouse experiment. Native rhizobia populations ranged from 3.2 × 10(1) to 3.5 × 10(4) cells per gram of soil. Pure bacterial cultures isolated from fresh and healthy root nodules exhibited typical characteristics of Rhizobium sp. on yeast extract mannitol agar media supplemented with Congo red. Bean inoculation with the isolates significantly (p < 0.05) increased the shoot dry weight and nitrogen (N) concentration and content. The SE of all the native rhizobia were higher when compared to a reference strain, CIAT 899 (67%), and ranged from 74% to 170%. Four isolates had SE above a second reference strain, Strain 446 (110%). Our results demonstrate the presence of native rhizobia that are potentially superior to the commercial inoculants. These can be exploited to enhance bean inoculation programmes in the region.
authors.affiliation: Department of Applied Plant Sciences, Maseno University, Maseno, Kenya; Department of Pure and Applied Sciences, Technical University of Mombasa, P.O. Box 90420, Kenya.
authors.forename: Fanuel
authors.initials: F
authors.lastname: Kawaka
authors.affiliation: Department of Applied Plant Sciences, Maseno University, Maseno, Kenya.
authors.forename: Mathews M
authors.initials: MM
authors.lastname: Dida
authors.affiliation: Department of Soil Science, Maseno University, Maseno, Kenya.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Opala
authors.affiliation: Department of Plant Sciences, Kenyatta University, P.O. Box 43844-00100, Nairobi, Kenya.
authors.forename: Omwoyo
authors.initials: O
authors.lastname: Ombori
authors.affiliation: Department of Microbiology, Kenyatta University, P.O. Box 43844-00100, Nairobi, Kenya.
authors.forename: John
authors.initials: J
authors.lastname: Maingi
authors.affiliation: Department of Microbiology, Kenyatta University, P.O. Box 43844-00100, Nairobi, Kenya.
authors.forename: Newton
authors.initials: N
authors.lastname: Osoro
authors.affiliation: Department of Biochemistry and Biotechnology, Kenyatta University, P.O. Box 43844-00100, Nairobi, Kenya.
authors.forename: Morris
authors.initials: M
authors.lastname: Muthini
authors.affiliation: Department of Soil Science, Makerere University, P.O. Box 7062, Kampala, Uganda.
authors.forename: Alice
authors.initials: A
authors.lastname: Amoding
authors.affiliation: Faculty of Applied Sciences, Kigali Institute of Science and Technology, P.O. Box 3900, Kigali, Rwanda.
authors.forename: Dative
authors.initials: D
authors.lastname: Mukaminega
authors.affiliation: Department of Biological Sciences, Masinde Muliro University of Science and Technology, P.O. Box 190-50100, Kenya.
authors.forename: John
authors.initials: J
authors.lastname: Muoma