The production of indole-3-acetic acid (IAA) by these bacteria was determined using Salper’s reagent (Gordon and Paleg, 1957). Three milliliters of fresh Salper’s reagent (1 mL 0.5 M FeCl3 in 50 mL 37% HClO4 ) was added to free-cell supernatant and kept in com-plete darkness for 30 min at room temperature, and the optical density at 535 nm was measured in each treatment (Wöhler, 1997).A standard curve was also prepared for IAA determination.