Abstract Indole-3-acetic acid production was monitored in nine plant growth-promoting rhizobacteria isolated from the rhizospheric soil of alfalfa(Medicago saiva). The isolate producing maximum amount of IAA was identified puida UB1 by 16S rRNA partial gene sequencing. Further investigations were carried out for optimal tryptophan concentration and other growth parameters for IAA production by P. putida. IAA production increased when the L tryptophan medium for IAA production was supplemented with sucrose 0.5%, (NH4)2SO 10 mg/m and tryptophan 0.2 mg/ml at pH 7.5. Maximum IAA production was achieved at 96 h. Production of IAA was confirmed by extraction of crude IAA and thin-layer chromatography analysis. The specific spot from the extracted IAA was found to correspond with a spot of standard IAA with the same Rr value(0.36). The crude IAA was further purified by passing it through a silica gel column. P. putida UB1 and its purified IAA were demonstrated to show stimulatory effect on mustard(Brassica nigra) plants in vitro with their incorporation in MS medium as a novel approach.