抗菌药对紫花苜蓿萌发的生态毒性作用

【目的】探明土霉素、磺胺嘧啶和氧氟沙星残留对紫花苜蓿种子萌发和幼苗生长的影响，了解3种药物对牧草的生态毒理效应，以期为评价畜禽排泄物中抗菌药污染对生态安全的影响提供科学依据。【方法】试验采用水培法，3种药物均设7个浓度梯度，分别为0（CK）、0.1、0.5、1.0、5.0、10.0和50.0μg/mL，分析不同浓度药物对紫花苜蓿种子萌发特性、幼苗生长及叶绿素含量的影响。【结果】≥50.0μg/mL的土霉素能显著抑制紫花苜蓿种子萌发（P<0.05），其余2种药物对紫花苜蓿种子的萌发均无显著影响（P>0.05）。除≤0.5μg/mL磺胺嘧啶对紫花苜蓿株高有促进作用外，其他药物对紫花苜蓿幼苗根长和株高均起抑制作用，且抑制作用整体上表现为根长>株高，高浓度（5.0~50.0μg/mL）抑制作用相对较强；不同浓度土霉素处理均能增加紫花苜蓿幼苗干重，而磺胺嘧啶和氧氟沙星在较低浓度时（≤1.0μg/mL）可不同程度地增加紫花苜蓿幼苗干重，高浓度（>5.0μg/mL）时则减少紫花苜蓿幼苗干重；随浓度的增加，磺胺嘧啶和土霉素可降低紫花苜蓿幼苗含水量，而氧氟沙星处理下紫花苜蓿幼苗含水量先减后增。3种药物对紫花苜蓿幼苗叶片叶绿素含量的影响表现为氧氟沙星>磺胺嘧啶>土霉素，且土霉素和氧氟沙星处理的叶绿素含量均随药物物浓度的增加而降低。【结论】磺胺嘧啶和氧氟沙星各浓度下对紫花苜蓿种子萌发基本无影响，高浓度土霉素可抑制种子萌发；3种抗菌药对根长、株高、干重、含水量及叶绿素均有不同程度影响，主要损伤体现在对根长、株高的伸长和叶绿素合成的抑制。

Ecological toxicity of antibiotics on the germination of Medicago sativa

【Objective】 This study explored the effects of oxytetracycline,sulfadiazine and ofloxacin residues in livestock manure on the germination and seeding growth of Medicago sativa to understand the ecotoxicological effects of these three drugs on forage crops and to provide a scientific basis for the evaluation of the effects of antimicrobials in livestock and poultry excreta on ecological security.【Method】 Ahydroponic method was used with seven concentrations of each antibiotic[0(CK),0.1,0.5,1.0,5.0,10.0 and 50.0 μg/mL]to analyze their effects on germination characteristics,seedling growth and chlorophyll content in M. sativa.【Results】 Oxytetracycline at ≥ 50.0 μg/mL significantly inhibited the seed germination of M. sativa(P<0.05),while the other two drugs had no significant effect(P>0.05). Sulfadiazine promoted greater plant height at ≤ 0.5 μg/mL,while the other drugs had a significant inhibitory effect on the root length and,to a lesser extent,plant height of seedlings at higher concentrations(5.0-50.0 μg/mL). Different concentrations of oxytetracycline increased the dry weight of M. sativa seedlings,while increases were observed with sulfadiazine and ofloxacin only at lower concentrations(≤ 1.0 μg/mL);higher concentrations(>5.0 μg/mL)caused decreases. Sulfadiazine and oxytetracycline caused larger decreases in seedling water content with increasing concentration,while ofloxacin caused the water content to decrease at lower concentrations but water content increased at higher concentrations. The three antibiotics caused decreases in chlorophyll content in the order of ofloxacin>sulfadiazine>oxytetracycline. The chlorophyll content of oxytetracycline and ofloxacin decreased with increasing concentration.【Conclusion】 Sulfadiazine and ofloxacin have little effect on M. sativa germination at all concentrations tested,whereas high concentrations of oxytetracycline inhibited germination.The three antibacterial drugs have different effects on root length,plant height,dry weight,water content and chlorophyll,with the main deleterious effects being the inhibition of root length,plant height and chlorophyll synthesis.