• axenic conditions;
  • endogenous IAA;
  • GC–MS analysis;
  • indole-3-acetic acid;
  • plant associated bacteria


Aims:  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.

Methods and Results:  Gas chromatography and mass spectrometric (GC–MS) analysis revealed that bacterial strains produced 0·6–8·22 μg 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.

Conclusions:  Bacterial strains have the ability to increase the endogenous IAA content and growth of T. aestivum var. Inqalab-91.

Significance and Impact of the Study:  Microbial strains of wild herbaceous flora can be effectively used to enhance the growth and yield of agronomically important crops.