Effects Of Growth Regulator EBR And Chelating Agent EDDS On Lead Absorption,Translocation And Accumulation Ability Of Tall Fescue

Lead(Pb)is one of the most dangerous pollutants in the environent which is hardly migrate or break down through natural processes,posing a serious threat to the ecological environment and human health.The present study was carried out to investigate the effects of application of plant growth regulator 2,4-epibrassinolide(EBR),the biodegradable chelating agent S,S-ethylenediaminedisuccinic acid(EDDS)and combination of those two at different concentrations on the growth and lead absorption,translocation and accumulation of tall fescue under 1000mg/kg lead stress.And explore the potential of combined application of EBR and EDDS to enhance the phytoremediation of Pb of tall fescue,and to obtain the optimal concentration of EBR and EDDS to provide a theoretical reference and data support for exploring the combination of "plant growth regulator +chelating agent" on the phytoremediation of Pb contaminated soil of tall fescue.(1)The growth of tall fescue exposure to Pb stress was inhibited,and EBR treatment improved the growth of tall fescue,enhanced its stress tolerance,and final meliorated oxidative stress.The mechanism may be that EBR can induce the expression,transcription and translation of the resistant gene of tall fescue to regulate the division and elongation of plant cells and related physiological metabolic systems.and promote the gene synthesis by regulating the expression of multiple endogenous hormones.Furthermore,EBR can affect the synthesis of endogenous hormones and the interaction between endogenous hormones and regulates the endogenous hormone levels of plants to maintain their balance under Pb stress.Among all the EBR treatments,0.1mg/L EBR application was the best to enhance the resistance and lead transport ability of tall fescue.(2)The application of EDDS increased the bioavailable Pb content in the soil and promoted the absorption and accumulation of Pb from the soil of the tall fescue,and the Pb content and translocation factor of the plant showed an upward trend accompanied by the increation of the concentration of EDDS.Among all the EDDS treatments,0.1g/kg EDDS and 0.2g/kg EDDS had no significant effects on the biomass of tall fescue,but 0.3g/kg EDDS significantly inhibited the biomass.(3)The present study showed that the combination of EBR and EDDS at the appropriate concentration not only increased the biomass of tall fescue,but also significantly increased the accumulation and translocation of Pb.Among all the combinations,the combination of 0.1 mg/L EBR and 0.2 g/kg EDDS was the optical mode.In this mode,the bioconcentration factors of Pb in shoot and root increased by 20.41% and11.38%,respectively,and the translocation factor and extraction rate of heavy metals increased by 30.60% and 37.51%,which was the highest for all combined treatment groups.The biomass of shoot and root of tall fescue in this mode was also increased compared with the Pb treatment.(4)This study showed that the combination of 0.1mg/L EBR and 0.2g/kg EDDS can effectively the enhance the phytoremediation tall fescue under 1000mg/kg Pb stress.