Enhancement Of Chelating Agent And Antidote On Lolium Perenne To Remediate Pb Contaminated Soil

The bulletin of the national soil pollution survey shows that the heavy metal pollution in the south of China is so serious that how to develop and utilize land is an important problem to be solved urgently.Along with the promulgation of national soil pollution prevention action plan,the provinces have gradually introduced the programme of work of the local soil pollution control.Soil remediation has become an important issue to be resolved in our country currently for the good job of environmental protection.Phytoremediation with the characteristics of green economic and environmental protection has become the focus of remediation technology of heavy metal pollution plots to be developed at present repair.Remediation of soil heavy metal pollution by using Lolium Perenne,not only beautify the environment,purify air,fresh forage,but also has the characteristics of multi cutting resistance and a good tolerance of various heavy metal contaminated soil.A pot experiment was conducted to investigate Pb accumulation in Lolium perenne with brassinolide,ascorbic acid and EDTA alone or in combination on uptake.The results showed that 0.025~0.1mg/L BR alone,2.5mmol/kg EDTA alone,BR or AsA with EDTA in combination all significantly increased Pb content in shoots,promoting the underground Pb transfer to the shoot.Pb accumulation of shoots in accordance with the order as: EB(BR and EDTA in combination)> EDTA alone > EA(AsA and EDTA in combination)> AsA alone > BR alone.A pot experiment was conducted to study the effects on the contents of photosynthetic pigments,malondialdehyde(MDA),antioxidant(GSH and AsA)and antioxidant enzyme activities in shoots under different treatments.The results showed that suitable concentration of BR or AsA alone significantly increased the contents of chlorophyll a,chlorophyll b,SH,PCs and dry weight of plant in shoots,and enhanced plant photosynthesis performance and viability under adverse circumstances contaminated with Pb press;the AsA content was shown a significant positive correlation with the content,accumulation,enrichment and transfer coefficient of Pb in shoots.BR or AsA in combination with EDTA could continue increasing Pb enrichment,migration and MDA content,with the Pb stress and membrane lipid peroxidation strengthen persistently,and antioxidative effect was improved by increasing AsA content,increasing CAT and POD activity(AsA and EDTA fertilizer treatment except)and the decrease of APX with the Pb polluted.A pot experiment was conducted to study the effects of different treatments on the subcellular and chemical forms.The results showed that compared with BR or AsA alone,BR,AsA and EDTA fertilizer further increased Pb content of ryegrass,while the cell wall and the soluble component proportion rising,and cell wall and cell organelles in roots increasing.So it could be known that cell wall and liquid bubble holding compartment is an alleviate detoxification mechanism of Pb stress under combined application,NaCl extractable,acetic acid extractable and hydrochloric acid extractable ratio in shoots and hydrochloric acid extractable ratio in roots were increased by BR alone,while ethanol extractable and water extractable ratio were increased significantly by BR and EDTA fertilizers along with the acid extractable ratio increasing slightly;the acetic acid extractable ratio in shoots and acetic acid extraction,hydrochloric acid extractable ratio in roots were increased by AsA alone.At last,AsA conbinated tiand EDTA fertilizer,acetic acid extraction ratio in shoots and roots were increased by AsA combined EDTA.It can be seen that increasing the ratio of inert state of acetic acid and hydrochloric acid extraction is an important mechanism for reducing the toxicity of Pb,which provides favorable conditions for Pb enrichment.A pot experiment was conducted to study the distribution of nutrients in the upper and lower parts of Lolium perenne.The results showed that K content in shoots was significantly increased by 0.1mg/L BR alone,while 0.05mg/L or 0.1mg/L BR alone significantly reduced N content of shoots and roots;with the increasing of AsA concentration,the K content increased significantly,and the content of N decreased significantly for 0.5mg/Lor1mg/L AsA alone.With the promotion of the transfer of K to the upper part of the basement,the loss of Ca,Mg and N elements in shoots and roots was accelerated.Therefore,the application of a certain proportion of nutrient solution to the soil can promote the growth of Lolium Perenne.