الفهرس 
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Abstract
The objectives of the present study were isolation and screening rhizobia isolated from the root nodules of seven different sites at Suez Canal region during the period from October 2014 to March 2015. Phenotyptic and genotypic characterizations were investigated for rhizobial isolates. The ability of the selected rhizobial isolates for solubilization of inorganic phosphates, production of siderophores and auxins (indole acetic acid, IAA), and root colonizationwas also studied.
Of a total of 109 bacterial cultures isolated from the root nodules, 34 were purified and then used for further investigation. The tested isolates varied greatly in their efficiency for producing IAA equivalents and siderophores and solubilizing of inorganic phosphates and the ability to colonize corn and wheat.
A field experiment was conducted using 7 rhizobial strains and the strain Bacillus subtilis to evaluate the effect of inoculation with rhizobial strains on corn yield, NPK contents, soil pH and available PK. Soil available PK values were higher at flowering and harvesting stages of maize comparing with their initial values. The inoculation with Bacillus subtilis gave the highest values of soil available PK compared with the different rhizobialstrains. Inoculating with the different bacterial strains resulting in a marked decrease in soil pH values compared with the initial value.Dramatic decreases in soil pH between the different bacterial strains were obtained and the inoculation with Bacillus subtilisgave much lowering in soil pH compared with the rhizobialstrains. Inoculation with different microbial strains resulted in significant increases in dry weight of maize plants compared with the control treatment at flowering and harvesting stages. The highest shoot dry weight at flowering stage (after 60 days from sowing date) was obtained with Sinorhizobium meliloti RM3166 where the increase over the uninoculated control was 28.9%. At harvesting stage (after 120 days from sowing date), the highest maize stover and grain yields were recorded with the bacterial strains Rhizobium leguminosarum bv. trifolii 462 and Bacillus subtilis where the increases over the uninoculated corresponding control were 5.23 and 9.36%, respectively
The results of this study indicated highly beneficial effects of rhizobiaonmaizeas cereal crops, under field conditions. The tested Rhizobial strains are recommended for further evaluations using different non-legume plants and using different soils and environmental conditions before being generalized and adopted in a bio-farming system.