Özet:
Many agricultural soils of Iran have high pH, resulting in low availability of Fe and Zn. The potentials of nonsymbiotic
plant growth-promoting rhizbacteria (PGPR) for stimulating plant growth have been extensively used
during recent decades. This experiment was carried out in growth chamber to evaluate the effects of siderophoreproducing
Pseudomonads on the growth as well as Fe and Zn uptake of wheat. A randomized complete block
design experiments was conducted using with Alborz genotype (an efficient phytosiderophore-producing bread
wheat) treated with either 7NSK2 strain as a siderophore positive (sid+) or with MPFM1 mutant strain of the same
isolate as a siderophore negative (sid-) treatments with three replications. The potentials of these strains for auxin
production and phosphate solubilizing activity were evaluated by standard methods. The results showed that
inoculation with sid+ strain increased dry matter production in shoots as compared with the control (sterile
condition) or with sid - strain. Likewise, the concentration of chlorophyll a in leaves of sid+ and sid - treatments were
1.27 and 0.41 g mg-1 of fresh weight, respectively, and the concentration of chlorophyll b were measured to be 1.09
and 0.35 g mg-1 of fresh weight, respectively, indicating significantly more chlorophyll formation due to inoculation
with sid+ as compared with sid -. The uptake of Fe by roots and its rate of translocation to the shoots were greater
for the sid+ treated plants as compared with the sid - treated ones, indicating that siderophores increased the rate
of Fe uptake by wheat. The effect of microbial inoculation on shoot Zn was not significant, but increased the
concentration of Zn on roots compared with control. The results suggested that the siderophores of Pseudomonads
may involve on increasing bioavailability of iron.
