An Evaluation of Some Plant Growth-Promoting Characteristics of Drought Resistant NativePseudomonas fluorescens Strains and Growth Indices as well as Yield in Wheat



Drought tolerances of 55 indigenous strains of Pseudomonas fluorescens were evaluated. To assess the tolerance rate of the strains to various levels of water deficit, their growth rate in NB medium containing concentrations of 40.587, 438.838 and 548.838 g of polyethylene glycol 6000 per liter of medium were utilized. Water potentials of aforesaid levels were estimated as 0, - 10, - 20 and -30 bar, respectively. A Number of 39 strains could grow under water stress conditions for which the production of ACC-deaminase enzyme as well as Indole-3- Acetic Acid (IAA) hormone were studied. Among them, some Pseudomonas fluorescens strains were selected as superior ones for greenhouse experiments. The experiments were performed through factorial arrangement in a Randomized Complete Block Design of three replications. The results revealed that 25.64 vs. 23.07 percent of the tolerant strains were able to produce high levels of ACC- deaminase enzyme vs. Indole-3- Acetic Acid (IAA) hormone, respectively. The greenhouse results indicated that inoculation of plants with superior strains (IAA&ACC-deaminase) significantly increased growth indices as well as yield as compared with control under any of the water stress or normal conditions.