فاطمه جمالی

Wheat take-all caused by Gaeumanomyces graminis var. tritici (Ggt) is one of the most important soil-borne diseases causing significant damage to the crop every year. Fluorescent pseudomonads are able to control plant pathogens through producing different metabolites including antibiotics, siderophores, hydrogen cyanide, extracellular enzymes and inducing systemic resistance. 24 strains of fluorescent Pseudomonas spp. harboring phlD gene isolated from the rhizisphere of different crops were evaluated based on preventing mycelial growth of Ggt through dual culture method on NA PDA culture medium. Among them, four strains including Wkz1-87, B1-1-, W20 and BD8 showing the highest inhibitory effect on pathogen growth were selected for the next studies. The ability to produce antimicrobial metabolites (protease and hydrogen cyanide) and plant growth promoting traits (inorganic phosphate solubilization, and production of siderophore and indol acetic acid (IAA) were estimated under in vitro conditions. Results revealed that B1-3 and W20 strains had the greatest ability to produce hydrogen cyanide, protease, siderophore and IAA and to solubilize inorganic phosphate. Then the effect of four strains was evaluated on germination traits of wheat cv. Zarrin Madari under in vitro conditions and the results showed that all four strains had positive effects on germination attributed traits; however, Wkz1- 87 and BD8 strains performed better in comparison to others. To investigate the influence of fluorescent pseudomonads on yield and yield components of wheat, an experiment was performed under completely random design in three replications during 1396-97 in the research greenhouse, faculty of agriculture and natural resources, Persian Gulf University, Bushehr. Result revealed that bacterial strains showed a significant difference regarding their effect on wheat yield. All selected strains had positive impacts on disease control, plant growth promotion and induction of defense enzym