Isolation, identification and evaluation of sidrophore production in Pseudomonas bacteria and its effect on hydroponically grown corn

Pseudomonas bacteria are the most important plant growth promoting rhizobacteria (PGPR) in different crop plants. In this study، thirty eight Pseudomonas bacteria isolated from corn rhizosphere grown in different parts of Khorasan Razavi province. Initially، all isolates were identified by using recommended physiological and biochemical tests. The results showed that most of Pseudomonas isolates were similar to Pseudomonas fluorescens and Pseudomonas aeruginosa. The potential sidrophore production of all Pseudomonas isolates was evaluated using CAS-agar solid medium. The results of this part of experiment showed that the ratio of halo to colony diameter varied from 0. 7175 to 4 after four days of incubation at 27 oC. The quantity of sidrophore production of Pseudomonas isolates was also measured by using spectrophotometry method. The results revealed that the amount of sidrophore production changed from 0. 96 to 132. 5 µML-1 among Pseudomonas isolates. The effect of sidrophore–iron complexes on growth of corn plant was investigated in a hydroponic system under green house condition. The results showed that chlorophyll content، shoot and root dried weights significantly increased when sidrophore–iron complexes was applied to corn plant. The effect of sidrophore-iron complex took out from Pseudomonas fluorescens on iron uptake in corn plant was similar to Fe–EDTA complex. The effect of sidrophore-iron complex extracted from P16 isolate on iron uptake was significantly higher compare to control treatment.