Alemu, Tesfaye (PhD)Alemu, Fekadu2018-06-282023-11-092018-06-282023-11-092012-06http://etd.aau.edu.et/handle/123456789/4486Plant protection is an important area which needs attention since most of the hazardous inputs added into the agricultural system are in the form of plant protection chemicals. Production of the crop is, however, constrained by several infections including fungal diseases. The present study, Pseudomonas fluorescens isolates possess a variety of promising properties which make it a better biocontrol agent.Twelve Pseudomonas fluorescens isolates from rhizospheric soil of faba bean were evaluated for their antagonistic activity against Botrytis fabae that is known to attack faba bean crops. All Pseudomonas fluorescens isolates are employed in controlling chocolate spot diseases of plant. P. fluorescens10 (88.1%) showed high antagonistic activity against Botrytis fabae. In addition, all isolates were tested for antifungal activity against Botrytis fabae. All isolate of Pseudomonas fluorescens are indicated successfully employed in controlling chocolate spot diseases of plant due to their antifungal metabolites.The antifungal compounds were extracted from all P. fluorescens isolates with equal volume of ethyl acetate, hexane and methanol.The antifungal compounds extracted with ethyl acetate, hexane and methanol from P f3, P f8 and P f3 isolates at 0.1% concentration completely inhibited the pathogen growth respectively. Four fungicides were tested against B. fabae and Curzate ® WP and Sancozeb 80% were prevented mycelia growth at higher concentration (80mg/ml per plate). All isolates Pseudomonas fluorescens were assessed for their plant growth promoting activity based on their ability to produce hydrogen cyanide (HCN), siderophores, indole acetic acid (IAA), ammonia and phosphate solubilization. The results indicated that all most of the isolates tested possess plant growth promoting traits. Bio-primed faba bean seed with P f9 and P f10 for pathogencity test in green house was indicated to show positive result. Two isolates of P f9 and P f10 was reduced both disease severity and incidence, increasing faba bean number of leaves per plant, number of branches per plant, height of plants, root length of plant and lateral roots and number of nodule. The present study was also carried out for estimation of total phenols and flavonoids present in fresh faba bean leaf extract with ethanol. Applying the P f9 and P f10 by bio-primed seed of faba bean treatment enhanced the accumulation of total phenols and flavonoids compared to untreated infected and uninfected untreated faba bean. So it could be concluded that the used P f9 and P f10 could resist the detrimental effects of Botrytis fabae on the plant growth and yield. These isolates can be used as potential biofertilizers and also as biocontrol agents. Key words: Antifungal compounds, Botrytis fabae, Biocontrol, faba bean, Pseudomonas fluorescens, secondary metabolitesenAntifungal compoundsBotrytis fabaeBiocontrol, faba beanPseudomonas fluorescenssecondary metabolitesThesis