Abstract

Fluorescent pseudomonads are ubiquitous bacteria that are common inhabitants of the rhizosphere and are the most studied group within the genus Pseudomonas. Strain UTPF61 is a biocontrol agent againstSclerotinia wilt of sunflower, an important disease of sunflower caused by Sclerotinia sclerotiorum. Thisbacterium was selected out of 47 strains. It was grown in eight culture media containing different carbon sources, such as sucrose, glucose, corn steep liquor, fructose, glycerol, sugar beet molasses, manitol and starch. Our results showed that the starch has a considerable effect (P<0.01) on the rate of bacterial growth as compared to the other carbon sources used. Investigation of antifungal activity in vitro indicated that some media containing glucose and sugar beet molasses were the most effective (P<0.01) on antagonistic efficiency, whereas the medium containing sugar beet molasses was the most effective on antagonistic efficiency in greenhouse trials (with 87% healthy plants).

Key words: Antagonistic efficiency, antifungal activity, biological control, carbon sources, growth rate.