الفهرس 
Introduction and literature reviewOnly 14 pages are availabe for public view
 |  | from | 105 |  |  |
| | | from | 105 | | |
Abstract
The aim of this work was to isolate plant growth promoting rhizobacteria from faba bean plants, determine some phenotypic and biochemical characters (e.g., tolerance to salt, utilization of carbon and nitrogen sources and production of exopolysaccharides, catalase, urease, gelatinase enzymes, HCN production, ammonium, siderophores production, phosphate solubilization and ability of bacteria for inhibition of pathogenic fungi). Effect of salinity on growth and nitrogen fixation of Vicia faba plants was investigated. Effects of PGPR on growth of V. faba were determined under greenhouse conditions.
The results obtained in this study are summarized as the following:
* Rhizobia (18 isolates from V. faba)
* The bacterial isolates were confirmed as rhizobia by re-inoculating V. faba plants. About 8 isolates from V. faba succeeded to renodulate V. faba, four isolates (RV1, RV2, RV3 and RV4) were selected and used throughout the work as these four isolates gave higher nodule number and nitrogenase activity.
*Rhizobial isolates displayed various colony characteristics; some colonies were circular and milky or opaque when grown on YMA medium.
* Most of isolates showed growth at high concentration of NaCl up to 6%
* All isolates from V. faba were able to utilize glucose, sucrose and mannitol as carbon source and could produced high amount of exopolysaccharides. .
* The majority of isolates utilize yeast-extract, ammonium sulphate, ammonium phosphate and glutamic acid as nitrogen source and produced high amount of exopolysaccharides.
* All isolates showed positive catalase enzyme test, urease and gelatinase enzymes
* All isolates produced indole acetic acid with different amounts.
*One isolates could produced HCN and siderophores, two isolates produced ammonia, three isolates showed phosphate solubilization ability.
*Identification of isolates by useing 16SrRNA showed that isolates belong to of R. leguminosarum bv. Viciae with high similarity percentage.
* Effects of salinity on the growth, nodulation and nitrogen fixation of V. faba plants were determined. .
* Salinity reduced the dry weight of both shoots and roots, shoots were more sensitive to salinity than roots. Dry matter yield of shoots and roots, chlorophyll content and nitrogen content decreased as salt increase.
* But inoculated plant with different isolates of R. leguminosarum lead to increase fresh and dry weight of shoots and roots. And also chlorophyll content and nitrogen content were increased when plant inoculated with different isolates under salt stress NaCl (50 and 100 mM).
* Inoculation of faba bean plants with RV1, and RV3 gave better results than inoculation with RV2 and RV4 under salt stress.
* Effects of PGPR (R. legumonisarum, P. polymyxa and A. brasilense growth and nitrogen fixation of V. Faba plants under salt stress were determined.
* Salt stress reduced fresh and dry weight of shoots and roots, nitrogen, phosphorus protein and chlorophyll contents and increased proline, and also catalase and peroxidase activity increased as salt increased.
* Inoculation of plants with different PGPR increased dry and fresh weight of roots and shoots, leaf area, RWC%, nitrogen, phosphours, protein contents as compared to control (non-inoculated plant).
* Under non-saline conditions and after inoculation with rhizobium (RV1) alone or in combination with A. brasilense, a 37.69 KDa band appeared. The intensity of this band reduced under salt treatment.
* Plants inoculated with A. brasilense plus R. leguminosarum (RV1) at 100 mM NaCl showed the appearance of a 67.57 KDa band.
It is concluded that the bacteria examined in this study are good plant growth-promoting rhizobacteria (PGPR), and is suggested to be a good candidate as a biofertilizer in sustainable agriculture.