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Title: Plant Growth Promoting Properties of Rhizobacteria Isolated from Chickpea and Lentil Producing Areas of Ethiopia
Other Titles: Implication for Productivity in Low-inputs Agricultural System
???metadata.dc.contributor.*???: Dr. Fassil Assefa
Jida, Mulissa
Keywords: IAA;Mesorhizobimn Species;PGPR;PSB;Rhizobiwn Species
Issue Date: Jun-2013
Publisher: Addis Ababa University
Abstract: Chickpea (Cicer arielitmm L.) and lentil (Lens culnaris 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 properties of chickpea and lentil nodulating rhizobia and phosphate solubilizing bacterial isolates from major producing areas of the country. Accordingly, a total of 157 bacterial isolates were obtained and characterized using different standard methods. Phenotypic and plant growth promoting characteristics of 66 rhizobia! isolates recovered from root nodules of chickpea and lentil grown in soils collected from producing areas of the country were investigated. These rhizobia 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 show'ed a wide diversity among these rhizobial isolates. Moreover, some of these rhizobial isolates exhibited plant growth promoting characteristics such as phosphate solubilization, 1AA production and antagonistic activity against Fusarium oxysporum. In addition, a total of 91 phosphate solubilizing bacterial isolates were obtained from chickpea and lentil rhizosphere soil samples collected from different producing areas of the country. These isolates w'ere identified using the API biochemical test kits and partial 16S rDNA sequences analysis. The result showed the presence of genera such as Acinetobacter, Aeromonas, Agrobacterium, Bacillus, Brevibacillus, Burkholderia, Chryseomonas, Empedobacter, Euterobacter, Pseudomonas, Ralstonia, Sphingomonas and Stenotrophomonas. 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 Fitsariim oxysporum growth under in 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 field conditions.
Description: A Thesis Submitted to the School of Graduate Studies of the Addis Ababa University in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Biology (Applied Microbiology)
Appears in Collections:Thesis- Microbial, Cellular and Molecular Biology

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