Chickpea is one of the major legume crops widely grown in Ethiopia. The low availability of phosphorus in soil is among the stresses that constrain the production of this crop in the country. However, there are rhizobacteria capable of solubilizing insoluble forms of phosphorus in soil and make it available to the plant. Thus, this study was aimed at isolation and characterization of phosphate solubilizing bacteria from chickpea rhizosphere. Fifty phosphate solubilizing bacterial strains were isolated from the soil samples, characterized biochemically and identified by 16S rDNA sequences analysis. The results indicate the presence of genera Acinetobacter, Bacillus, Brevibacillus, Burkholderia, Empedobacter, Enterobacter, Pseudomonas, Ralstonia, Sphingomonas and Stenotrophomonas. Phosphate solubilizing efficiencies of the strains were analyzed using different insoluble phosphorus sources and the results show that most isolates released a substantial amount of soluble phosphate from tricalcium phosphate, rock phosphate and bone meal. Screening for multiple plant growth promoting attributes showed that 44 and 18% of them were capable of producing indole acetic acid and inhibiting the growth of Fusarium oxysporum under in vitro conditions, respectively. A direct impact of several strains (Bacillus flexus (PSBC17), Pseudomonas fluorescence (PSBC33), Enterobacter sp. (PSBC35), Enterobacter sakazaki (PSBC79) and Enterobacter sp. (PSBC81)) on the growth of chickpea in pot culture has been demonstrated by the increase in the number of root nodules, shoot dry matter, nitrogen and phosphorus concentration of shoot. Based on the results, we conclude that chickpea rhizosphere harbor phosphate solubilizing bacteria which are diverse in taxonomy and phosphate solubilizing efficiencies. Thus, consecutive studies should focus on field studies on those strains due to their potentially high importance for the phosphorus nutrition of crops in this area and in this context for the improvement of the sustainability of crop production in the country.

Lentil (Lens culnarisMedik.) is an invaluable source of dietary protein for the majority of Ethiopian population. The low availability of phosphorus is one of the major soil related stresses that limit the production of this crop. This study was aimed at isolation and characterization of phosphate solubilizing bacteria from lentil growing areas of Ethiopia and evaluating their effects on growth of this crop under greenhouse conditions. In total, 41 phosphate solubilizing bacterial strains were isolated from lentil rhizosphere and characterized using biochemical tests and 16S rDNA sequence analysis. The results showed the presence of genera Acinetobacter, Agrobacterium, Bacillus, Burkholderia, Chryseomonas, Enterobacter, Pseudomonas, Ralstonia and Sphingomonas. Phosphate solubilzing efficiencies of these isolates were evaluated in liquid medium using different insoluble P-sources and the result indicated that they released considerable amount of phosphates from tricalcium phosphate, rock phosphate and bone meal. Besides, some of these isolates exhibited multiple plant growth promoting characteristics such as indole acetic acid production and growth inhibition of Fusarium oxysporum under in vitro conditions. The effects of inoculation of Enterobacter kobei (PSBL5), Bacillus subtilis (PSBL21), Enterobacter species (PSBL26), Bacillus species (PSBL31) and Pseudomonas fluorescence (PSBL37) on lentil growth, nodulation, N and P content of shoot were evaluated under a greenhouse conditions and the results showed that these features were significantly increased over uninoculated control plants. Based on the results of this study, we conclude that lentil rhizosphere soil from producing areas of Ethiopia harbor diverse phosphate solubilizing bacterial strains with excellent phosphate solubilization and plant growth promotion ability. Thus, most of the promising strains should be tested in the field conditions under different agroecology of the country.