The Symbiotic Effectiveness and Diversity of Root Nodule Bacteria of Some Acacia Spp. From Sodo Wereda, Guraghe Zone, Southern, Ethiopia.

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Addis Ababa University


The genus Acacia has a large number of species that are adapted in wide range of habitats in both tropical and temperate regions throughout the world for most of them fix nitrogen with rhizobia. However, nitrogen fixation by different species is not necessarily effective that needs compatibility of the rhizobia and the host varieties under different ecological conditions. Therefore, this was designed to isolate, phenotypically and symbiotically characterize acacia rhizobia from Sodo Woreda, Guraghe Zone, and Southern, Ethiopia under laboratory and greenhouse conditions. Thus, ten rhizobial isolates were collected from nodules of three different acacia species; Acacia seyal, Acacia abyssinica and Acacia negrii. They all induced nodulation upon re-inoculation on their homologous host plants. All isolates were fast growing, tolerant to high concentration of 6% NaCl concentration and grew over a wider range of temperature up to 43. Most of the isolates of Acacia abyssinica and one isolate of Acacia negrii, were capable of utilizing a various types of carbohydrates as carbon source. The symbiotic effectiveness of the isolates on the sand culture showed significant variations in nodule number, nodule dry weight, shoot dry weight, shoot length compared to their respective N- fertilized and N-fertilized -control groups. The maximum number of nodule and shoot dry weight of the inoculated plant were recorded by Acacia negrii with isolate AURAneg31.The minimum number of nodule was recorded by Acacia abyssinica with isolate AURAaby24.The highest shoot dry weight was observed N-fertilized (positive control) plant by Acacia seyal. However, shoot dry weight of N-unfertilized (negative control) plants less than both inoculated and uninoculated plants. Isolates of Acacia negrii, were very effective; AURAneg31 showed the highest value 91% of symbiotic effectiveness whereas both Acacia abyssinica and Acacia seyal were showed effective. Generally isolates of A. negrii were more competitive than other two species.



Acacia Abyssinica, Acacia Negrii, Acacia Seyal, Fas Growing, Rhizobia, Salt Tolerance, Symbioticeffectiveness