A critical examination of the specificity of the Salkowski reagent for indolic compounds produced by phytopathogenic bacteria

Abstract

We examined the sensitivity and the specificity of three versions of the Salkowski colorimetric technique. Two of these allowed the detection of indoleacetic acid (IAA) over a low range of concentrations (0.5 to 20 μg/ml), while the third permitted the detection of IAA over a range of higher concentrations (5 to 200 μg/ml). Overall, the three formulations reacted not only with auxin (IAA) but also with indolepyruvic acid and indoleacetamide. Therefore, these techniques appear to be specific for IAA, indolepyruvic acid, and indoleacetamide rather than for IAA alone.