Study On Ecotoxicity Of Antibiotics To Medicago Sativa L

Antibiotics play an important role in human medical treatment and animal production,which not only improves the cure rate of human diseases,but also greatly increases the economic benefits of aquaculture.With the abuse of antimicrobials by industrial production,human and aquaculture,a large number of antimicrobials,drug-resistant bacteria and resistance genes are discharged into the environment,posing a serious threat to human and ecological environment.Sulfonamides and tetracycline antibacterial drugs are widely used in the breeding industry for disease prevention,treatment and growth promotion due to their low price and high antibacterial activity.As a result,a large number of drugs are discharged into the environment in the form of prototypes and metabolites through feces and urine,bringing current harm and influence to the ecosystem.In this paper,we study on medicago sativa L as the research object,select the breeding residues higher veterinary antibiotic usage and environment-sulfadiazine(SD)and oxytetracycline(OTC),as a condition of stress,by using hydroponics + soil culture was investigated in different concentration antimicrobials environment,germination of medicago sativa L,the influence of the growth and physiological and biochemical indexes,makes a preliminary inquiry In order to provide a preliminary research basis for the evaluation of the ecological effects of antimicrobial residues in the excreta of livestock farms on the toxicity of forage.(1)In the concentration range of 0～50 g/m L,the two antimicrobials had no significant effect on the germination rate,germination potential and germination index of medicago sativa L seeds,and did not affect the seed germination.(2)Both antimicrobial agents had inhibitory effects on the root length of medicago sativa L,and the inhibition increased with the increase of the concentration.Low OTC concentration(0.1 g/m L～0.5 g/m L)can promote the differentiation of secondary structure of root,while high OTC concentration(10g/m L～50 g/m L)can inhibit the differentiation of secondary structure of root to a certain extent.However,under SD stress,root differentiation of medicago sativa L could be affected to different degrees,which was mainly reflected in morphological damage to epidermis and cortex parenchyma cells.(3)SD had a bidirectional effect on plant height.When the concentration was less than 0.5 g/m L,it could promote plant height to a certain extent,but when the concentration was more than 0.5 g/m L,it could significantly inhibit plant height.OTC had significant inhibitory effect on plant height at various concentrations.The dry weight of medicago sativa L can be decreased when SD is ≥50 g/m L,and the dry weight of medicago sativa L can be increased when OTC is 0.5 g/m L.SD and OTC can significantly reduce medicago sativa L water content when ≥5.0 g/m L.(4)The chlorophyll synthesis of medicago sativa L leaves was inhibited under the effects of the two antibiotics agents,and the inhibition was strengthened with the increase of concentration.(5)After 35 days of treatment with two antibiotics,medicago sativa L was damaged more and malondialdehyde(MDA)content increased with the increase of concentration.The activities of superoxide dismutase(SOD)and peroxidase(POD)in medicago sativa L were inhibited under the stress of two antimicrobial agents at different concentrations,and the activities decreased with the increase of concentration.Catalase(CAT)activity increased gradually with the increase of two drugs concentration.