Abstract

ISOLATION, CHARACTERIZATION AND EVALUATION OF SYMBIOSIS EFFICACY OF NITROGEN FIXING BACTERIA ON DOSHA FABA BEAN FROM SOIL COLLECTED IN SELECTED DISTRICTS OF AMHARA AND AFAR REGIONS, ETHIOPIA

Emebet Kibkab*, Nega Berhane and Tekeba Sisay

ABSTRACT

Nitrogen is the major limiting nutrient for crop growth in most agricultural soils. Chemical nitrogen fertilizers are very expensive and had an adverse effect on the environment and human health. Biological nitrogen fixation with rhizobia legumes symbiosis is one of the alternative solutions and the promising technologies. Therefore the aim of this was to isolate, characterize and evaluate the symbiosis efficacy of nitrogen fixing bacteria from soil collected in selected districts of Amhara and Afar Regions, Ethiopia. Thus, 20 isolates isolated from selected study sites. All isolates were characterized morphologically biochemical and physiologically. Isolates found gram negative, circular in shape, flat and smooth in colony morphology, motile and positive for citrate, catalase and oxidase, indole test and urease test, poor absorption on growth of glucose peptone agar medium, mucus nature on growth of hope‟s alkaline medium. Of 20 isolates 15 isolates were tolerated to pH (4.4 to 9), salt concentration (10 to 15%), and at a temperature of (35 to 40 °C). Physiologically pH, salt and temperature tolerant 15 isolates were used in the pot experiment using Dosha bean cultivar as host system. The mean plant dry biomass, nodule number, shoot number and root length inoculated plants showed variations among the different inoculated isolates (p<0.05). Eight (8) isolate amongst showed significant effect on Dosha bean cultivar dry biomass and nodule number amongst the 15 isolates. Therefore it is possible to conclude as eight best performing rhizobium isolates could be used as bio-fertilizer in Dosha bean cultivar farming in different soil conditions such acidic, alkaline, saline and in temperate environments.

Keywords: Biofertizer; Dosha faba bean; Legumes; rhizobium and symbiosis.