Enhance Remediation Of Cd Contaminated Soils By Lolium Perenne In Existing Of DA-6 Alone And In Combination With EDDS/MGDA

This article studied the DA-6 (diethl aminoethyl hexanoate) alone and in combination with EDDS (ethylene diamine disuccinate)/MGDA (methylglycinediacetic acid) impact on the Cd extraction efficiency of Lolium perenne, also discussed the role of different treatments in Cd detoxification mechanisms of Lolium Perenne aboveground by studing the subcellular distribution and chemical forms of Cd in Lolium perenne. By adding Cd(NO3)2 to the soil, this research prepared external Cd concentrations were 0,25,50,100 mg/kg soil.2.5 mmol/kg of EDDS and 5 mmol/kg of MGDA were added to the soil directly. DA-6, whose concentrations was 1,10,100, was sprayed to the leaves directly. The main findings are as follows:(1) DA-6 alone not only significantly promoted the Cd accumulation in Lolium Perenne, but also strengthened the plant antioxidant enzyme activity. The ratio of Cd in the cell wall (F1), plant biomass and chlorophyll synthesis was increased, MDA content, cell soluble component (F2) and organelles (F3) in proportion was decreased (P<0.05).(2) MGDA alone promoted the Cd accumulation in Lolium Perenne, strengthened the plant antioxidant enzyme activity; however, compared with the control, MDA content, F2 and F3 in proportion was increased, the ratio of Cd in Fl was decreased. So the plant biomass and chlorophyll synthesis reduced significantly (P<0.05). DA-6 in combined with EDDS/MGDA, not only can promoted the growth of Lolium perenne, but also significantly improved the Cd bioaccumulation factor and translocation factor of Lolium perenne. Under the condition of this experiment,1μM DA-6 combined with EDDS/MGDA was the most significant,1μM DA-6 combined with EDDS increased the Cd bioaccumulation factor and translocation factor of Lolium perenne by 0.7～2.7,1.3～2.0-fold,1μM DA-6 combined with MGDA increased the Cd bioaccumulation factor and translocation factor of Lolium perenne by 1.1～1.6,0.69～2.7-fold, as compared to the control.(3) The study of Cd chemical forms in Lolium perenne shoot showed that:a majority of Cd was associated with pectates and proteins (FNacl), followed by heavy metal-phosphate complexes (FHAC).Among different chemical forms, FE, Fw and FNaci are remarkably stronger migration ability than that of other chemical forms of Cd, and be more toxic to plant. The application of DA-6 significantly reduced the liquidity of Cd in the soil, alleviated Cd damage to the Lolium perenne. The addition of EDDS/MGDA increased the mobility of Cd, and enhanced the Cd damage to the Lolium perenne. Under the treatments of DA-6 along with EDDS/MGDA, Cd propotions on FE, FW and FNaCl was increased, but still lower than EDDS/MGDA treatment alone, indicating that DA-6 can effectively relieve the hazard of EDDS/MGDA on Lolium perenne.(4) As compared to the control, DA-6 and EDDS/MGDA brought great influence on the distribution of Cd in the soil, they all promoted the oxidation forms and reduction forms to transform into acid soluble forms in the soil. The acid-soluble forms of Cd have strong liquidity in soil, and were easily absorbed by plants, and enhanced the plant bioaccumulation of Cd.