| The ecotoxicological effects of oxytetracycline (OTC) on the germination of wheat (Triticum aestivum) seeds and the early development of wheat seedlings were investigated. The results showed that the elongation of wheat shoots and roots was significantly (p<0.05) inhibited by OTC, and there was a good dose-response relationship between the OTC concentration and inhibition rates. According to the linear regression equation, EC50of OTC for inhibiting wheat shoot and root elongation was 65.5 mg/Ｌ and 34.7 mg/Ｌ, respectively. However, the germination of wheat seeds was not inhibited by OTC. Moreover, after a 21-day exposure to 0.15-2.40 mg/Ｌ OTC, the content of chlorophyll (CHL) decreased by 35.6%-47.3%, and the content of soluble protein (SP) in the leaves and roots of wheat plants decreased significantly. After a 7-day exposure, the activity of SOD and POD in wheat was not changed significantly. With the prolongation of exposure time, the activity of SOD and POD in wheat leaves and roots decreased significantly, the inhibition rate of SOD activity in roots increased up to 72.3% after a 21-day exposure to 2.4 mg/Ｌ OTC, which indicated that the antioxidant defense systems were damaged. The results above suggested that the low concentration OTC had ecotoxicological effects onwheat seedlings after chronic exposure. |
