Potential of Capsicum annuum rhizosphere bacteria in inhibiting the growth of Fusarium oxysporum in-vitro

Abstract

The rhizosphere has been known to contain rich microbial community which is directly influenced by secretions of roots. Rhizosphere microbes are known to have various benefits such as protection of plant from pathogens and toxic compounds, producing plant growth hormone, nitrogen fixation, and solubilizing phosphate. The objective of this study was to obtain rhizosphere bacteria capable of inhibiting the growth Fusarium oxysporum which is common pathogen attaching Capsicum annum. Bacteria were isolated from rhizosphere C. annum of local farm in Kabanjahe North Sumatra. Nine isolates based on morphological performance and biochemical analyses were obtained. Antagonistic test showed that two isolates BR6 and BR9 inhibited the growth of F. oxysporum with inhibition rate of 60% and 52%, respectively after 7 days incubation. These isolates also exhibited the activity to solubilize phosphate in Pikovskaya media with solubility index of 3.04 and 2.77, respectively. The other isolate BR5 even showed higher phosphate solubility index (3.42). These results suggest these isolates may have important role to support the growth of C. annum by providing protection from pathogens and phosphate ion. Then, study on the control of F. oxysporum attack on C. annum seedlings using these potential isolates is in process in our laboratory, as well as their molecular identification based on 16S rRNA.