To gain insight into the effects of aqueous solutions of different dyes on plant performance and identify the most promising traits for fast assessment of toxicity, we studied the influences of two anthraquinone dyes (Optilan Blue and Lanasyn Blue) and four azo dyes (Lanasyn Red, Nylosan Red, Nylosan Dark Brown and Lanasyn Dark Brown) at two different concentrations (0.5 and 1.5 mg l−1) on foliage photosynthesis, photosynthetic pigments and emissions of lipoxygenase pathway products (LOX; green leaf volatiles) and monoterpenes in wheat (Triticum aestivum L. cv. “Lovrin”). Net assimilation rate was only inhibited by the highest concentration of Nylosan Red, while stomatal conductance to water vapor was strongly influenced by all azo dyes. Concentrations of photosynthetic pigments, chlorophylls and carotenoids, were most strongly reduced in treatments with azo dyes especially with those which contained chromium in their molecular structure. These data collectively indicate important reduction of foliage physiological activity by textile dyes and indicate that emissions of leaf volatiles can provide a promising tool to assess the toxicity of different dyes.