چكيده لاتين :
Fusarium root rot of bean caused by Fusarium solani f.sp. phaseoli is an important disease of this crop worldwide. In this study, biological control of the disease was examined using rhizosphere bacteria. One hundered and twenty two bacterial isolates from bean rhizophere were evaluated by dual culture on PDA media on antagonistic activity against Fusarium solani f.sp. phaseoli five isolates showing higher antifungal activity were selected for further investigation. Based on the biochemical, physiological and morphological characteristics, isolates B99 and B23 were identified as Bacillus cereus, and isolates B12, B80 and B83 as Bacillus subtilis.The ability of bacteria to produce liquid and volatile antifungal compounds, siderophores, cellulase and poisonous compounds such as hydrogen cyanide were studied in vitro. Volatile compounds and extracellular liquid metabolits of all tested isolates affected the pathogen and decreased its colony growth rate compared to the control. In cellulase test all of the isolates but B12, B99 and B83 were able to produce cellulase. None of the isolates produced hydrogen cyanide. The effects of selected bacteria isolates on disease severity, percentage of disease incidence and plant growth indexes using sterilized and nonsterilized soils by two methods comprising soil treatment and seed dressing treatment with bacteria were studied in vivo. In this study the isolates B83 and B12 decreased the disease severity to the levels of 1.7 and 2.1 respectively. The isolates B12, B80 and B83 decreased the disease incidence percentage to 17, 37 and 21 percent respectively. The isolates B12, B83 and B23 increased bean dry weight in seed dressing treatment method in sterile soil to 5.9, 5.5 and 4.5 gram respectively.
