Dr. Hoda Rashwan Ahmed Al-zoheri :: Publications:

Salinity is one of the most severe biotic stresses limiting crop growth and productivity. It is one of the main factors that limits the spread of plants in their natural habitats. In view of important role of some plant growth promoting rhizobacteria which have positively influence plants vitality and the ability of the plants to cope with a biotic stress conditions specially salinity, for this purpose, a succession of laboratory and pots experiment were designed and carried out. Obtained results can be summarized in the following. 5.1. Isolation and purification of plant growth promoting rhizobacteria (PGPR) This part concerning to isolation and purification of some plant growth promoting rhizobacteria from salt–affected soil samples that were collected from different location in Egypt. One hundred and sixty-five (165) bacterial isolates were obtained and consequently used for the succeeding experiments. 5.2. Screening of salt-tolerant isolates for prospective PGPR features 5.2.1. Salt-tolerant rhizobacterial assessment The primary screening of the rhizobacterial isolates was achieved under saline stress to investigate the most salt tolerant isolates. The screening was carried out in presence of different sodium chloride concentration using different specific microbiological media to give final salt concentration of 2, 4, 6, 8, 10, 12, 15, 18 and 20%.The obtained data showed that all examined rhizobacterial isolates showed salt tolerance up to 6% sodium chloride. While, 77.6%, 64.2% and 31.5% of the examined isolates showed salt tolerance at sodium chloride concentrations of 10%, 12% and 15%, respectively. Only 8.5% of the examined isolates showed salt tolerance at concentration of 20% sodium chloride. 5.2.2. Salt tolerant bacteria as PGPR Subsequently, the most salt-tolerant rhizobacterial isolates in the current study were chosen for further studies. Fifty-two isolates that showed salt-tolerance at 15% sodium chloride were used for the secondary screening which was carried out to investigate the ability of chosen isolates concerning the production of indole acetic acid (IAA), gibberellins, siderophores, hydrogen cyanide (HCN) and ammonia. Moreover, phosphate and potassium solubilization as well as N2-fertilization were considered.