Abstract

Since the Iranian soils are almost limy, application of Fluorescent pseudomonas have a major potential to
provide the microelements needed for crop plants due to their siderophore production ability. In this work three
indigenous high siderophore producing strains, a reference strain 7NSK2 and its pyoverdine mutant, MPFM1,
were employed. To explore their efficiency, siderophore production was investigated by CAS-agar method.
Effect of bacteria inoculation on the shoot and root dry weight increase as well as chlorophyll content of the crop
were assayed under greenhouse condition. Furthermore, synergistic effects of bacteria strains and iron chelates,
Fe-EDDHA and Fe-EDTA, and zinc sulphate on promotion of common bean plants were estimated. Strain
UTPF76 with 20.4 mm halo in CAS-agar medium had the highest siderophore production capability. The results
of the greenhouse experiments revealed that three of strains, 7NSK2, UTPF5 and UTPF76 increased the plant
growth factors significantly. Addition of iron chelates and zinc sulphate improved bacterial efficacy. Strains
MPFM1 and UTPF61 not only did not have positive effect on the plant growth but also in some cases decreased
the growth factors. In colonization survey UTPF76 and UTPF5 had the greatest colonization activity. In
conclusion, our results showed that indigenous stains have a high potential in biotechnological applications and
their industrial application is recommended.

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