Phenol-mediated suppression of soil-borne root-infecting fungi in mungbean

Abstract

Under field conditions, there is a variety of phenolic acids as well as other toxic and non-toxic organic
compounds that interact with plant seeds and roots; but in laboratory bioassays, with few exceptions, only single
phenolic acids are usually tested. In this study, the effect of various concentrations of two phenolics (caffeic acid
and p-hydroxybenzoic acid) on the wilt-inducing fungus Fusarium solani and the damping-off fungus Rhizoctonia
solani was tested in pot experiments. The effect of these phenolics on the biocontrol efficacy of Pseudomonas
aeruginosa, a plant growth-promoting rhizobacterium, was also evaluated. Caffeic acid and p-hydroxybenzoic acid
significantly suppressed F. solani and R. solani infection in mungbean. However, high concentrations of the phenolic
acids interfered with plant growth. P. aeruginosa in the rhizosphere declined in the presence of caffeic acid
and p-hydroxybenzoic acid.