الفهرس 
1. INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 109 |  |  |
| | | from | 109 | | |
Abstract
The present work aimed to isolate,screen and identify plant growth promoting rhizobacteria (PGPR) obtained from the rhizosphere soil of eight field crops cultivated at different locations in Ismailia and Sharkia Governorates for using them as biofertilizers. The selected rhizobacteria were tested for their ability to solubilize inorganic phosphate and to produce indole acetic acid, (IAA) and siderophores in vitro. Of a total of 233 bacterial cultures, 26 isolates were selected and identified by cultural, morphological and biochemical characteristics. Identification of themost efficient 10 isolates on growth and yieldof wheat cv. Sakha 94were confirmed by 16S rRNA gene sequencing. The 26 isolates were identified to the 6 genera Bacillus, Micrococcus, Enterobacter, Serratia, Citrobacter and Pseudomonas.All isolates solubilized insoluble phosphate and produce IAA, while 17 of them were able to produce siderophores. Significant increases over the uninoculated control in available P and counts of total bacteria in soil after wheat harvest were found, while soil pH decreased and a highly significant negative correlation was observed between soil pH values and levels of soil available P. Significant increases in grain and straw yields as well as in uptake of N and P by plants were obtained due to inoculation with the tested isolates.The PGPR inoculated-wheat plants showed higher contents of all photosynthetic pigments (chlorophyll a, b and carotenoids) in flag leaf than the uninoculated plants.Levels of free amino acids, free phenolic compounds and reducing sugars in roots, flag leaf and spikes were significantly enhanced by application of all PGPR isolates compared to the untreated control. Estimation of soluble storage protein in wheat grains using one dimensional SDS-PAGE exhibited the beneficial effect of PGPR inoculation on the over-expression of Gliadins and both HMW and LMW of Glutenins.
The results of this study showed beneficial impacts of the tested PGPR on wheat growth and yield, some soil properties, contents of all photosynthetic pigments (chlorophyll a, b and carotenoids) in flag leaf , levels of free amino acids, free phenols and reducing sugars in roots, flag leaf and spikes. The tested PGPR are recommended for field evaluation under different soils and environmental conditions before generalizing as biofertilizers.
Keywords: plant growth promoting rhizobacteria, 16S rRNA gene sequencing, total bacteria, indole acetic acid, siderophores, P solubilization, plant macromolecules, protein electrophoresis, wheat.