Auxin production by plant associated bacteria: impact on endogenous IAA content and growth of Triticum aestivum L.

The aim of this study was to investigate the potential of bacterial strains of Bacillus, Pseudomonas, Escherichia, Micrococcus and Staphylococcus genera associated with wild herbaceous flora to enhance endogenous indole-3-acetic acid (IAA) content and growth of Triticum aestivum var. Inqalab-91. Gas chromatography and mass spectrometric (GC-MS) analysis revealed that bacterial strains produced 0.6-8.22 mu g IAA ml(-1) in the presence of L-tryptophan. Plant microbe experiments showed a significant positive correlation between auxin production by bacterial strains and endogenous IAA content of T. aestivum for GC-MS (r = 0.618; P = 0.05) and colorimetric analysis (r = 0.693; P = 0.01). Similarly, highly significant positive correlation for shoot length (r = 0.627; P = 0.01) and shoot fresh weight (r = 0.626; P = 0.01) was observed with auxin production under axenic conditions. Bacterial inoculations also enhanced shoot length (up to 29.16%), number of tillers (up to 97.35%), spike length (up to 25.20%) and seed weight (up to 13.70%) at final harvest. Bacterial strains have the ability to increase the endogenous IAA content and growth of T. aestivum var. Inqalab-91. Microbial strains of wild herbaceous flora can be effectively used to enhance the growth and yield of agronomically important crops.