生菜对土霉素的吸收及其植物毒性

Uptake of Oxytetracycline and Its Phytotoxicity to Lettuce

通过水培实验研究了土霉素在植物体内的吸收及其植物毒性。实验选取不同初始浓度的土霉素营养液(1、5、10mg·L-1),培养18d,结果发现,营养液中土霉素的浓度越高,生菜对土霉素的吸收量越大。土霉素浓度为1mg·L-1时,根部表现出抑制作用。当土霉素的浓度高于5mg·L-1时,生菜根和叶的生长均受到显著抑制;生菜对水分的吸收减少;对部分微量元素(Fe、Cu、Zn、Mn)的吸收也受到抑制,这可能与土霉素的络合有关;土霉素浓度越高,抑制作用越明显。土霉素为1mg·L-1,营养液pH值5～8条件下,发现pH对生菜吸收土霉素有一定的影响,但对生菜生长的影响不显著。

Oxytetracycline （OTC） is one of broad-spectrum antibiotics, which may enter the environment through various pathways and cause potential ecotoxicological effects. Experiments were conducted in hydroponic system to investigate the uptake of OTC and its phytotoxicity to lettuce. The effeets of OTC （1 - 10 mg·L^-1） on lettuce were evaluated after cultivating for 18 days. It was found that the OTC uptake by lettuee increased with the initial OTC concentrations increasing. The growth of lettuce root was inhibited at the OTC eoneentration of 1mg·L^-1, but the foliage was not affeeted. Under the eoncentrations of OTC more than 5 mg· L^-1, both root and foliage exhibited phytotoxieity response, and the root was more sensitive to OTC than foliage. Furthermore, with the increase of initial OTC concentration, the water absorption capacity tended to decrease, and the uptake of trace elements （Fe, Cu, Zn and Mn）by lettuce were inhibited as well, whieh may be due to the complexation of OTC with metals. In the four traee elements, the inhibition effect of Mn by OTC was more remarkable than the other three metals, and the inhibition of Zn was the least, pH could affect the uptake of OTC （ 1 mg·L^-1OTC, pH 5-8）, but the influence of pH on the growth of lettuee was not significant. The results are helpful to assess the uptake and phytotoxicity of OTC to plants.