两种四环素类兽药抗生素对白菜种子发芽与根伸长抑制的毒性效应

采用土培和水培相结合的方法,在预试验研究的基础上,研究砖红壤中不同质量分数金霉素（0～4 000 mg·kg-1）、土霉素（0～25 000 mg·kg-1）和水溶液中不同质量浓度金霉素（0～150 mg·L-1）和土霉素（0～150 mg·L-1）污染对白菜（Brassica pekimensis）种子发芽的抑制与毒性效应。结果表明：（1）当土壤中添加外源土霉素时,白菜种子发芽率总体呈下降趋势。而当添加金霉素时,白菜种子发芽率在85%附近波动,与对照相比,并无显著差异（P〉0.05）。而在水培条件下,金霉素对白菜发芽的抑制作用大于土霉素,但并未达显著差异水平（P〉0.05）。（2）白菜根伸长量随着土壤、水溶液中土霉素和金霉素质量分数或质量浓度的增加而缩短,生长均受到抑制。且与两种抗生素的质量分数或质量浓度均表现为极显著的相关性（P〈0.01）。（3）同一质量分数或质量浓度水平下,发芽率、根伸长、芽伸长对金霉素和土霉素的生态毒性敏感顺序依次为根伸长〉芽伸长〉发芽率。根伸长抑制率可作为诊断土霉素、金霉素对土壤毒性的敏感指标,反映土壤被四环素类抗生素污染的状况。（4）金霉素和土霉素在水培条件下对白菜的IC50值分别为20.32和287.52 mg·L-1。而在土壤中,白菜对金霉素和土霉素的IC50值分别为851.08和14 045.75 mg·kg-1。说明在土霉素对白菜的毒性作用小于金霉素,并且2种抗生素在土壤中对白菜根伸长的抑制效应明显低于水溶液中的抑制效应,这与土壤对抗生素污染有重要的缓冲作用有关。

Toxicological effects of two tetracycline antibiotics on the inhibition of seed germination and root elongation of Chinese cabbages

The individual chlorotetracycline and oxytetracycline pollution on the inhibition rates of seed germination and Eco-toxicity effects of Chinese cabbages（Brassica pekimensis） were tested with antibiotics spiked into the water and soils.The concentration of chlorotetracycline（soil： 0～4 000 mg·kg-1;water solution： 0～150 mg·L-1） and oxytetracycline（soil： 0～25 000 mg·kg-1;water solution： 0～150 mg·L-1） was determined based on the pre-experiments.Results showed germination rate,root elongation and shoot elongation had eco-toxicity sensibility due to chlorotetracycline and oxytetracycline stress.The germination rate of Chinese cabbages showed downtrend with exogenous oxytetracycline amendment.However,it slightly fluctuated around 85% with chlorotetracycline amendment,which didnt appear significant difference（P〉0.05） compared with the control.Although there was no significant difference（P〉0.05）,chlorotetracycline showed stronger inhibition on germination of Chinese cabbages than oxytetracycline under hydroponic culture conditions.The growth of Chinese cabbages was inhibited with addition of oxytetracycline and chlorotetracycline,shown as shortened root elongation with the increase of concentrations of oxytetracycline and chlorotetracycline in soil and solution.The root elongation of Chinese cabbages was significantly related with concentrations of those two antibiotics.Sequence orders was root elongation 〉 shoot elongation 〉 germination rate,in which the control rate of root elongation was better index for evaluating 2 kinds of antibiotics eco-toxicity.Chlorotetracycline and oxytetracycline in water solution on IC50 of root elongation was 20.32 mg·L-1,287.52 mg·L-1,respectively in soil was 851.08 mg/kg,14 045.75 mg·kg-1,which indicated that the toxicity effect of oxytetracycline on vegetable was less than chlorotetracycline.Meanwhile,the inhibition effects of antibiotics on the root elongation of Chinese cabbages in soils were much lower than that in water,indicating that soils played an important role of buffering on antibiotics pollution.