Single and joint toxicity of chlorimuron-ethyl, cadmium, and copper acting on wheat Triticum aestivum.

Investigation of the toxicological effects of some agricultural pollutants on germination rate and on shoot and root elongation of wheat (Triticum aestivum) was carried out. Seeds of wheat were exposed to various concentrations of chlorimuron-ethyl with or without cadmium and copper addition. The inhibitory rates of seed germination and shoot and root elongation of wheat were calculated. Significant linear relationships between the root and shoot elongation and the concentration of chlorimuron-ethyl with or without copper or cadmium addition were observed. The interactive effects of the three pollutants on seed germination were not significant (P > 0.05), but on shoot and root elongation they were markedly significant (P < 0.01). When concentrations of added Cd2+ or Cu2+ reached the concentration under which the inhibitory rate of wheat root elongation was about 20%, cadmium (or copper) and chlorimuron-ethyl had an antagonistic effect on the inhibition of shoot and root elongation, although the interactive effects of copper were not significant (P > 0.05). However, cadmium (or copper) and chlorimuron-ethyl had significantly synergic effects on the inhibition of shoot and root elongation (P < 0.05) when concentrations of added Cd2+ and Cu2+ reached the concentrations under which the inhibitory rate of root elongation was about 70%. At the high concentration of added cadmium or copper, joint toxicity of chlorimuron-ethyl and the heavy metals was more dependent on the concentrations of the latter. The sensitivity of wheat to the toxicity of the three pollutants was in the following sequence: root elongation>shoot elongation>germination rate.