Out of seven isolates used in this study, only two isolates
(StBn and RtBn) showed IAA production in the range of
7.2–8.9 lg/ml in the presence of tryptophan in YPM
(Table 1). The YPM medium supplemented with tryptophan
acts as precursor of IAA. PGP is accomplished by different
mechanisms, such as, solubilisation of essential minerals,
increased nutrient uptake, production of certain phytohormones
like IAA, vitamins, enzymes and suppression of
pathogens through siderophores or by bio-control agents.