Abstract: In order to understand the influence of antibiotics on crop growth， oxytetracycline， which is widely used in livestock and poultry breeding in China， was selected to test the effects of different levels of antibiotics pollution on growth of rice seedlings， root activity， chlorophyll content and oxidase activity by hydroponic experiment. The results showed that the effects of soil oxytetracycline pollution on the underground part were greater than on the above-ground part of rice. Low oxytetracycline concentration （0.5 and 1 mg·L-1） increased root length and total root surface area， and enhanced root activity. But the high concentration of oxytetracycline （>5 mg·L-1） significantly reduced rice root biomass and chlorophyll content， restricted root activity and oxidase activity， and increased the relative membrane permeability of root. In conclusion， high concentrations of antibiotic could cause toxic effects on rice seedlings， which would limit the normal growth of rice seedlings.

Key words: rice, rice seedlings；oxytetracycline, toxicology