Pseudomonas fluorescens and Bacillus subtilis isolated from rhizosphere of healthy groundnut plants were screened for their antagonistic activity towards the crown rot pathogen Aspergillus niger in Arachis hypogaea L. Invitro assay revealed that 10% of the isolates were antagonistic in nature and they were tested for their ability to produce growth promoting substances such as Auxin and Extracellular Phosphatase. Green house studies, with the application of Pseudomonas fluorescens 04 (80% inhibition of pathogen & 7.14mg/l auxin production) and Bacillus subtilis 03 (80% inhibition of pathogen & 79|jg/l phosphatase production), to Arachis hypogaea L. showed increase in growth, biochemical constituents and yield of test plants than that of control.

Keywords: Pseudomonas fluorescens, Bacillus subtilis, Aspergillus niger, Auxin, Phosphatase.