Relationship between Hydrogen Cyanide and Siderophore Production by Fluorescent Pseudomonads of Wheat Rhizosphere with Growth Rate of the Plant

The majority of rhizospheric bacteria, particularly fluorescent pseudomonads are able to stimulate plant growth by producing different metabolites including hydrogen cyanide and siderophores. To evaluate the effect of these metabolites on wheat growth, strains of fluorescent pseudomonads were isolated from the wheat rhizosphere in Khorasan provinces, identified and studied for production of hydrogen cyanide and siderophore through Alstrom and Castaneda methods. Results showed 16 out of 130 strains were positive in production of hydrogen cyanide and siderophore at different levels. A suspension of 108 bacteria per ml with 1% carboxy methylcellulose in distilled water was prepared for each of the16 strains. The wheat seeds (Triticum aestivum cultivar Phalat) were maintained for 30 minutes in each suspension and then dried. Five seeds were sown in pots each containing 1 Kg of autoclaved soil and maintained in greenhouse conditions with 17 treat and 3 repeat. One month later the fresh weights of the plants were determined and compared with control. The results indicated that the strains which possess the ability to produce hydrogen cyanide and siderophore increased the fresh weight, root, and height of the plants as compared to control. The correlation ratios observed between strains producing hydrogen cyanide and siderophore vs the fresh weights of the plants were rated as 0.84 and 0.93, respectively.