Antagonistic Activities of Pseudomonas Fluorescens Isolates, As A Bicontrol of Botrytis Fabae (Chocolate Spot Disease), Plant Growth Promoter and Inducer of Physiological Activities of Faba Bean (Vicia Faba)
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Date
2012-06
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Addis Ababa University
Abstract
Plant 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 metabolites
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Keywords
Antifungal compounds, Botrytis fabae, Biocontrol, faba bean, Pseudomonas fluorescens, secondary metabolites