[Effects of Tetracycline Antibiotics on Growth and Characteristics of Enrichment and Transformation in Two Vegetables]

Pot experiments were carried out to study different levels (0, 50, and 150 mg·kg^-1) of three tetracycline antibiotics[tetracycline (TC), oxytetracycline (OTC), and chlortetracycline (CTC)] on the growth, concentration of tetracycline antibiotics, and their characteristics of enrichment and transformation in two kinds of vegetables (lettuce and Chinese cabbage). The results showed that the fresh weight of shoots and roots of lettuce decreased by 1.56%-26.84% and 17.36%-51.04%, respectively, when exposed to tetracycline antibiotics compared to the control, while the fresh weight of shoots and roots of Chinese cabbage increased by 3.7%-7.3% and 3.1%-82.2%, respectively. The stomatal conductance (G_s) and transpiration rate (T_r) of lettuce and cabbage increased when exposed to tetracycline antibiotics, while the net photosynthetic rate (P_n) of lettuce decreased by 32.43%-82.43% at 150 mg·kg^-1 of TC compared to the control. Compared to the control, the activities of SOD in lettuce and cabbage decreased 29.17%-223.12% when exposed to tetracycline antibiotics, and the lowest activities of SOD in lettuce and cabbage were found in OTC treatments. The highest content of MDA in lettuce and cabbage was observed at 150 mg·kg^-1 of TC (except for lettuce leaves). The contents of tetracycline antibiotics in the shoots and underground portions of Chinese cabbage were higher than that of lettuce, and higher contents of tetracycline antibiotics in vegetables were found with the CTC treatments. The residual amount of antibiotics in lettuce soil was higher than that in the Chinese cabbage soil, and the highest residual amount in the soil was observed with the OTC treatment. The bioconcentration factors (BCF) and transport factor (TF) of Chinese cabbage were, respectively, 1.07-7.35 and 1.15-2.25 times that of lettuce. OTC and CTC were more easily concentrated in the two vegetables. Therefore, OTC and CTC may bring a higher ecological risk.