The Biological Control of Important Faba Bean Root Rot Agents Caused by Rhizospheric Antagonist Bacteria

Some types of Faba bean suspected of root pathogens in Lorestan provincec, Iran were sampled during years 2007 to 2008. After some pathogenicity tests, 121 samples which suffered from root fungus disease and from chromista were totally isolated. The abundance of fungi, Fusarium solani, which caused the faba bean root rot was more than that of the other separated types and as well as the farming damages throughout the province looked more. The next respective abundant species were: Fusarium oxysporum, Rhizoctonia solani, Macrophomina phaseolina, and Pythium sp. A Pythium and Macrophomina, were first report for these species from Iran. In addition to these referred to agents, 57 bacterial strains from the above mentioned fields and from the rhizosphere of faba bean were also isolated. They were tested for antibiosis quality as well as inhibiting strains that were selected through formation of inhibiting halo in the presence of pathogens. Strains were identified by the aid of biochemical, morphological, and physiological attributes. The strains of, R10 and R14 were recognized as the genus Rhizobium and the strains P42, P34, P38 and P8, as belonging to the genus of Pseudomonas. These strains were applied in two modes of: 1) soil treatment, 2) seeds being soaked against pathogenic agents. The results revealed that when the bacterial suspension carrying Rhizoctonia solani, Macrophomina phaseolina, and Fusarium solani was added to the soil, the dry weight of the plant would be 1, 0.36, and 0.37 g respectively. When the seeds were soaked, the plants polluted with, Fusarium solani, Macrophomina phaseolina, and Rhizoctonia solani had the dry weights of, 0.34, 0.41, and 0.43 g. These results revealed that the growing factors of the plants which had an influence on the two isolations (when the soil was polluted) were increased, but these factors (in the case of two isolations of Marophomina phaseolina), were intensified only when the seeds soaked. All in all the results indicated that the strains of P8, P34, P38, and P42 were significantly the most effective in increasing the dry weights of the plants.