نوع مقاله : مقاله پژوهشی
نویسندگان
1 عضو هیات علمی دانشگاه ارومیه
2 استادیار پژوهش موسسه تحقیفات خاک وآب
3 استاد دانشگاه مازندران
4 استاد دانشگاه تربیت مدرس
5 استادیار پژوهش موسسه تحقیقات خاک و آب
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
The potentials of non-symbiotic rhizbacteria for stimulating plant growth have been extensively used during recent decades. The objective of this investigation was to determine the potentials of some indigenous fluorescent Pseudomondas for siderophore production. For this purpose, some 201 strains of Pseudomonas putida, Pseudomonas fluorescens, and Pseudomonas aeruginosa were studied. Also two imported PGPR strains belonging to the Pseudomonas genus (7NSK2 and GRP3) were used as positive controls (sid+), and MPFMI strain was used as negative control (sid-). The potentials of these strains for siderophore production were evaluated by chrome azorel-S assay (CAS blue agar) through color change. The blue CAS-agar medium was inoculated in a drop plate method with 5 microliter of fresh culture suspensions having a controlled population density of 5 x108 CFU/ml in three replications. The diameter of colonies and orange halos around the colonies and their ratio were determined 24, 48, 72, and 96 hours after the inoculation. The results showed that 100% of the Pseudomonas strains were capable of growing on the CAS-agar medium and producing siderophore. The advance of color change was measured to be less than 15 mm/day for 25% of the strains, 15-20 mm/day for 61% of the strains, and more than 20 mm/day for 14% of the strains. A large percentage (75%) of the group with high potentials for siderophore production consisted of Pseudomonas fluorescens strains. Regarding the potential of these strains for siderophore production, the most abundant strain lay within the medium range (15-20 mm/day). The best strains FP136 and FP93 producing about 24 mm/day belonged to the Pseudomonas fluorescens strain. Furthermore, strains FP45, FP165, FP159, FP120, FP190, and FP106 from various species showed much greater potentials for siderophore production as compared with the strains 7NSK2 and GRP3. Considering the superior potentials of FP93, and FP159 strains for auxin production and for solubilizing insoluble phosphates, they are recommended for the production of PGPR inoculum.
کلیدواژهها [English]