Role of Secondary Metabolite Production by Pseudomonas fluorescens in the Suppression of Meloidogyne incognita

An experiment was conducted to understand the mechanism of action of bacterial antagonist, Pseudomonas fluorescens on root knot nematode, Meloidogyne incognita under laboratory conditions. One of the mechanism of P. fluorescens is production of secondary metabolites viz., ammonia and salicylic acid was confirmed by using qualitative and quantitative assay in vitro. The synthetic ammonia and salicylic acid (SA) were tested at different concentrations against hatching and mortality of M. incognita at 24, 48 and 72 h intervals. Among the different concentrations, 0.5% conc. of ammonia recorded as lowest egg hatching(40.60 juveniles/egg mass) and highest juvenile mortality(39.0%) over control. Similar results were observed in salicylic acid @ 1000 ppm conc. showed that reductionin hatch ability(44.22 juveniles/egg mass) and increase in juvenile mortality(38.00%) of M.incognita at 72 h intervals. It is concluded that the effect of ammonia and salicylic acid caused significant inhibition in egg hatching and mortality of juveniles of M. incognita and their effect is positively correlated to their concentrations and period of exposure.