Biocontrol effects of endophytic and rhizospheric bacteria against the root pathogen Fusarium oxysporum of hot pepper (Capsicum annum L.)

Abstract

Plant disease needs to be controlled to keep the quality of products and the abundance of food produced by farmers all over the world. Hot pepper production in Ethiopia has been reduced from time to time. This is mainly due to the outbreak of different diseases especially fusarium wilt in the hot pepper growing areas. The objective of this study was to isolate and characterize Plant Growth Promoting Bacteria from the hot pepper rhizosphere and internal tissues with potential biocontrol activity against Fusarium oxysporum. Thirty healthy and vigorous hot pepper plants with intact roots and soil from the rhizospheric region were collected randomly from hot pepper growing areas of Yimali Kebele. A total of 23 endophytic and rhizospheric bacteria were isolated from the hot pepper root and rhizospheric soil. The combined endophytic and rhizospheric bacteria showed a significant effect on the growth of F. oxysporum than single isolates (P d”0.05). The bacteria isolated from Markofana hot pepper varieties of black clay soil showed a better antagonistic effect on F. oxysporum than bacteria isolated from local hot pepper varieties of reddish sandy soil. A significant percentage of inhibition between combined endophytic and rhizospheric bacteria [endophytic (GE) + rhizospheric (GR) isolates] compared to GE+GE and GR+GR (P =0.002) was obtained. Antagonistic bacterial isolates were able to produce different hydrolytic enzymes such as chitinase, protease, and cellulase. Bacillus species showed better antagonistic performance and decreased radial growth of F. oxysporum than Pseudomonas species.