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.