Enhancement of Wheat Growth and Zn Content in Grains by Zinc Solubilizing Bacteria

Two bacterial isolates (B₁ and B₂), recovered from the rice rhizosphere produced siderophore and indole acetic acid and solubilized insoluble phosphate, ZnO and ZnSO_4.7H₂O. Based on routine biochemical tests, both the isolates were characterized as species of Pseudomonas. A shift in pH from 7 to 5 was observed in minimal medium supplemented with Zn compounds after 15 days of bacterial growth. Isolate B₁ solubilized maximum amount of ZnO (1.348ppm) after 15 days of incubation. In a pot experiment on wheat (PBW 373), application of bacterial isolates and their consortium with ZnSO_4.7H₂O @ 5mM significantly enhanced plant height, chlorophyll, grain number per plant over control after 90 days of sowing. Consortium (B1B2) treated wheat plants showed 31% increase in grain Zn over control. HPLC analysis of the root extract of bacterized wheat plants showed the dominance of oxalic, maleic, á-ketoglutaric and fumaric acid. Presence of higher amount of valine and leucine, sugar, protein and phenolic compounds was observed in the root extracts of consortium treated wheat plants than control.

Bacterial isolates B₁ and B₂, solubilized insoluble phosphate (ZnO and ZnSO₄7H₂O) and were characterized as Pseudomonas.

B1 solubilized maximum Zn (1.348ppm) when grown on Zn compounds, after 15 days of incubation.

During growth on Zn compound both the isolates produced acids and lowered down the pH from 7 to 5.

Enhancement of plant growth parameters and 31% increase in grain Zn over control was observed during application of bacterial isolates and their consortium with ZnSO_4.7H₂O @ 5mM to wheat, in a pot experiment.

Root extracts of wheat were found to contain high amount of amino acids, protein and organic acids.