Abstract

POTENTIAL OF BACILLUS ISOLATES AS BIOCONTROL AGENT AGAINST FUSARIUM WILT OF BANANA

V. Anusuya and G. Manimekalai*

ABSTRACT

Soil borne plant pathogens cause annual economic losses in most of the crops. In nature microbial interactions involve competition, hyper parasitism or antibiosis and these phenomena play an important role in striking ecological balance and keeping several plant pathogens in check. It is observed that plant growth promoting rhizobacteria (PGPR) influence the growth and yield of many plants. In this study, isolates of Bacillus, one of the important PGPR, were isolated from rhizosphere soils. Three Bacillus isolates 1, 2 and 3 were screened in vitro for their plant growth promoting traits like production of indole acetic acid (IAA), ammonia, HCN, phosphate, siderophore and evaluated for the ability to suppress fusarial growth. All the isolates were able to produce IAA, ammonia, HCN and siderophore but none of the isolates solubilized phosphorous. Production of IAA and siderophore was highest in the Bacillus isolates 3 (127 g/ml and 124% respectively) and lowest in Bacillus isolates 2 (35 g/ml and 24% respectively). In-vitro screening for antagonism against F. oxysporum revealed significant inhibitory effects on mycelial radial growth by all the three isolates. Among the three Bacillus isolates, isolate 3 showed highest inhibitions of 0.21, 0.20 and 3.24 cm in well diffusion, streak and point inoculation method respectively.

Keywords: PGPR, Bacillus, Fusarium oxysporum, Siderophore production.