Biocontrol potential of Pseudomonas fluorescens against bacterial wilt of Brinjal and its possible plant growth promoting effects

The present study was undertaken to explore the possibility of using an indigenous strain of Pseudomonas fluorescens to manage one of the most devastating disease of the economically important brinjal crop, the bacterial wilt. The bacterial wilt caused by Ralstonia solanacearum has severly limited brinjal production in all parts of the world. In an attempt to evolve a biological management of the disease, the antagonistic strain of P. fluorescens was applied as suspension in pot experiment by different methods viz. seed, root, soil, and their integration methods seed+root, root+soil, seed+soil and seed+ root+soil. The control treatments were inoculated control (only pathogen inoculated) and uninoculated control (neither pathogen nor antagonist inoculated). The percent wilt incidence (PWI) was found to be lowest (33.33%) in root+soil and seed+root+soil treatment of the antagonist. The population dynamics of the pathogen and antagonist in brinjal rhizosphere soil showed that the crop receiving seed+root+soil treatment had the lowest population recovery of the pathogen 26×10 cfu/g (7.33) and correspondingly highest population recovery of the antagonist 179.67×10 cfu/g (8.25). The correlation studies established a negative correlation between PWI and population density of P. fluorescens as well as between population densities of R. solanacearum and P. fluorescens. The yield, yield attributes and physiological and biochemical parameters were also found to be best performing in the seed+root+soil treatment of the antagonist suspension indicating its potential as PGPR.