Plant Growth Promoting Properties of Rhizobactel'ia Isolated from Chickpea and Lentil Producing Areas of Ethiopia: Implication for Productivity in Low-inputs Agricultural system

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Addis Ababa Universty


Chickpea (Cieer arielinulIl L.) and lentil (Lens euinaris Medik.) are among the major sources of dietary protein for the majority of population in Ethiopia. They also restore and maintain soil fertility through their symbiotic nitrogen-fixation in association with rhizobia. This study was intended to investigate plant growth promoting propelties of chickpea and lentil nodulating rhizobia and phosphate solubilizing bacterial isolates fi'om major producing areas of the country. Accordingly, a total of 157 bacterial isolates were obtained and characterized using different standard methods. Phenotypic and plant gro\\1h promoting characteristics of 66 rhizobia I isolates recovered fi'omroot nodules of chickpea and lentil grown in soils collected fi'Dln producing areas of the country were investigated. These rhizobial isolates showed wide diversity in their different C and N-sources utilization pattern and tolerance to salinity, high temperatures, acid and alkaline pH, heavy metals and antibiotics. Symbiotic and morphological characterization also showed a wide diversity among these rhizobial isolates. Moreover, some of these rhizobial isolates exhibited plant groMh promoting characteristics such as phosphate solubilization, IAA production and antagonistic activity against FusariulIl o.\)'sporulll. In addition, a total of 91 phosphate solubilizing bacterial isolates were obtained fi'om chickpea and lentil rhizosphere soil samples collected fi'om different producing areas of the country. These isolates were identified using the API biochemical test kits and partial 16S rDNA sequences analysis. The result showed the presence of genera such as Aeinelobacler, Aerolllonas, Agl'ObacleriulIl, Bacillus, Brevibacillus, BUl'khoideria, Chl)iSeOmOnas, Empedobaclel', Enlel'Obaclel', Pseudomonlls, Raislonia, Sphingomonas and Slenoll'Ophomonas. Phosphate solubilizing efficiency of the isolates was assessed qualitatively using solubilization index and quantitatively. Quantitative estimation of the phosphate solubilization efficiency of different insoluble phosphorus sources showed that most isolates have good solubilization ability of tricalcium phosphate, rock phosphate and bone meal. Furthermore, some of these isolates showed multiple plant growth promoting characteristics; production of indole acetic acid and fluorescent siderophore, and inhibition of FusariulII oxysporulII growth under ill vitro conditions. The effects of inoculation of isolates with multiple plant growth promoting properties on chickpea and lentil growth in pot culture showed significant improvement in number of nodules, shoot dry matter, shoot nitrogen and phosphorus contents. Generally, the present study indicated that Ethiopian soils contain symbiotically effective chickpea and lentil rhizobia which are endowed with different plant growth promoting attributes. Moreover, chickpea and lentil rhizosphere harbor phosphate solubilizing bacteria which are diverse in their taxonomy and phosphate solubilizing efficiency. Some of these isolates are of particular interest for further research under different tield conditions. Key words: IAA, MesorhizohiulII species, PGPR, PSB, RhizobiulII species



IAA, MesorhizohiulII species, PGPR, PSB