DOI: 10.36347/sajb.2019.v07i01.005

Pages: 27-33

Azo dyes and pigments are widely used for dyeing and printing in textile industries owing to their good fixative properties and cost affectivity. Azo dyes may enter the soil through the discharge of untreated effluents of dye and textile industries. Soil, contaminated/polluted by the azo dyes, is known to be phytotoxic. Presently, we have studied the effect of soil contamination by some azo dyes at different concentrations, on the seed germination and plant growth of Bengal gram (Cicer arietinum). Four azo dyes viz., 1-(2’-carboxyphenylazo)-2-naphthol, 5-(2’-carboxyphenylazo)-8-hydroxyquinoline, 4-(2’-carboxyphenylazo) salicylate and 4-(2’-carboxyphenylazo) resorcinol were synthesized and characterized. Calculated quantities of the above dyes were separately mixed with the known weight of soil in separate earthen pots, so as to obtain a dye concentration (w/w) of 200, 400, 600, 800 and 1000 ppm in the soil. Thus, a total of twenty experimental sets (dye-contaminated soil) and one control set (pure soil) were set up. The dyes were thoroughly mixed with the soil so as to obtain a uniform distribution of the dye in the soil. Ten seeds of Bengal gram (Cicer arietinum) were sown in each of the experimental pots as well as in the control pot. Proper sunlight and moisture were provided to the pots. Seed germination and plant growth were observed regularly. The morphogenic parameters of the plants such as, root length shoot length and number of leaves was found out at the end of 25 days. Mean value of each of the parameters for each of the set were determined. Percentage inhibition of the parameters, as compared to the control, were also determined. Results revealed a mild to severe phytotoxicity of the azo dye-contamination of soil on the plants of Bengal gram (Cicer arietinum). Chemical nature of the azo dye also seemed to rule the level of toxicity. Percentage germination ranged from 40 to 80% in the experimental sets. The plants in the experimental sets had generally a