Symbiotic and Phenotypic Characterization of Rhizobia Nodulating Common Bean (Phaseolus vulgaris L.) from Eastern Ethiopia

Argaw, Anteneh (2007) Symbiotic and Phenotypic Characterization of Rhizobia Nodulating Common Bean (Phaseolus vulgaris L.) from Eastern Ethiopia. Masters thesis, Addis Ababa University.

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Common bean (Phaseolus vulgaris L.) is the most widely distributed and has the broadest range of genetic resources. In Ethiopia, the yield of common bean is extremely low mainly due to nitrogen deficiency and also little information is available regarding diversity of rhizobia nodulating common bean. Hence, this study initiated to know their phenotypic diversity and maximize the symbiotic nitrogen fixation with common bean in Eastern Ethiopia in particular, 72 isolates of bean rhizobia were isolated from three zones, where common bean is commonly cultivated. The efficiency of infectivity and effectiveness of isolates was examined using the Awash Melka variety. Results revealed that 62 isolates were able to form nodules on the roots of the common bean variety and 10 isolates failed to nodulate the host. The tested isolates showed two different ranges of growth rates: 61 isolates as fast growing and isolate NSPVR-62 from Goro Gutu woreda as slow growing. The numerical analysis of the phenotypic characteristics of 62 isolates formed two major diversity groups based on 75% level of relative similarity. The phenotypic characterization and the numerical analysis indicated that 57 isolates as Rhizobium leguminosarum-like or Rhizobium etli-like, 4 isolates as Rhizobium gallicum-like and 1 isolate as Bradyrhizobium-like rhizobia were isolated from Eastern Ethiopia soils nodulating common bean. On the basis of preliminary screening of symbiotic effectiveness on sand culture from 62 isolates, 89% of them are effective and very effective in terms of symbiotic effectiveness. Based on SDW yield, strains NSPVR-2 from Eastern Shewa Zone and NSPVR-26, NSPVR-29, and NSPVR-31 from Western Hararghe Zone were selected to study symbiotic effectiveness on Ayenew and Awash Melka varieties on Melkassa and Babille soils. From the selected isolates, isolate NSPVR-31 showed different effectiveness of nitrogen fixation on Awash Melka and Ayenew varieties. While isolate NSPVR-29 showed significantly (p<0.01) higher SDW than uninoculated plants on both Ayenew and Awash Melka varieties. Therefore, isolate NSPVR-29 could be used as an inoculum on Babille soil on both tested varieties. Nevertheless, on Melkassa soil on Ayenew and Awash Melka varieties showed that nonstatistical difference of SDW, plant nitrogen contents, nodule number, and weight among all treatments. This is due to Melkassa soil has sufficient number of effective rhizobia nodulating common bean. Isolates NSPVR-8 and NSPVR-11 both from Bost woreda showed TCP solubilizer under preliminary screening of phosphorus solubilization and effective nitrogen fixers. We conclude that significant variation exists among rhizobial isolates nodulating common bean in Eastern Ethiopia and can be possible to select superior rhizobia that is in terms of symbiotic effectiveness, competitiveness ability and tolerate to adverse conditions.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Common bean, Rhizobia, Eastern Ethiopia, Phenotypic, Symbiotic effectiveness, TCP solubilizer.
Subjects: Q Science > QH Natural history > QH301 Biology
Q Science > QH Natural history > QH426 Genetics
Q Science > QK Botany
Divisions: Africana
Depositing User: Selom Ghislain
Date Deposited: 16 Aug 2018 08:45
Last Modified: 16 Aug 2018 08:45

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