Phytotoxic effect of synthetic dye effluents on seed germination and early growth of red amaranth

Among the industrial chemical wastes, the effluents of loom-dyeing industry raise great concern in recent times because of their diverse environmental hazards. A laboratory experiment was conducted to determine the phytotoxic effect of different loom-dye effluents on seed germination and early seedling growth of red amaranth (Amaranthus tricolor L.) in the Department of Agricultural Chemistry of Bangladesh Agricultural University, Mymensingh, during May to August, 2017. Results revealed that the physico-chemical parameters of loom-dye effluent such as pH, electrical conductivity (EC), total dissolved solids (TDS), sulphate, phosphate, sodium, potassium, iron, manganese and lead concentrations were relatively higher than the suggested range. On the other hand, the concentrations of calcium, zinc, copper and cadmium were relatively lower. Germination experiment of red amaranth were done in sterilized petridishes containing 0, 5, 10, 25, 50, 75 and 100% concentrations of three different types of untreated loom-dyeing effluents following completely randomized design. Three replications were used for each treatment. The germination energy and capacity, growth parameters like root and shoot length, relative toxicity, seedling vigour and phytotoxicity on seed germination of red amaranth in response to different loom-dyeing effluents at various concentrations were also calculated. There was a gradual lessening in the percentage of seed germination and seedling growth with increased concentration of effluents. Relative toxicity and phytotoxicity was extreme at 100% effluent concentration. Different growth parameters such as root and shoot lengths of seedlings was minimum at 100% and maximum at 5% dye effluent concentration. Overall results indicate that pink dye effluent was less toxic to the germination and early growth of red amaranth than violet and black dyes. For most of the growth parameters of red amaranth, the order of phytotoxicity among the loom-dye effluent was black > violet > pink.