Influence And Mechanism Of Copper Uptake And Transfer By Costor (Ricinus Communis L.) Under Nitrogen, Phosphorus Application

Heavy metal phytoremediation technology has been considered as a hopeful prospect because of its the advantages of cost-effective.While the plants used for phytoremediation was restricted by the regions,local environment and so on.To enhancthe uptake of heavy metals by tolerant plants which has been found in the polluted areas attracted a wide spread attention all over the world.Based on the previous studies,castor bean(Ricinus communis L.),discovered in Daye Tonglvshan copper mine area in Hubei Province,is choosed as the research subject/material in this study.Effects of both nitrogen(N)and phosphate(P)fertilizers on the uptake and transfer of Cu in castor bean plants from soil or water media were studied.In this study,we carried out the pot experiment with artificially polluted soil to explore the effects of different concentrations and forms of N(nitrate and ammonium)on Cu uptake and transfer in castor bean plants,and also we conducted the hydroponic experiment to determined that the effects of nitrate and ammonium withvarous concentrations and different treated time on the uptake and transfer of Cu in castor bean.The effects of combination of N and P fertilizers on the uptake of Cu by castor bean plant with pot experiment.The major results we get in this study were summarized as follows:1.Planted castor in the artificial contaminated soil with N addition,the results showed that,the biomass of castor bean significantly increased with the rise of concentrations of NH4+-N and NO3--N applied.The castor's biomass under NO3--N treatment was significantly higher than that of NH4+-N treatment in the same level of applied N.NH4+-N treatment made the amount of Cu accumulation increased significantly in the root of castor.With the increase of N concentration,the Cu transfer rate of castor increased at the first and then decreased.When the concentration of N treatment was 150 mg/kg,the Cu transfer rate of castor was the highest(which of NH4+-N was 0.34 and that of NO3--N was 0.54).When the N concentration was the same,the transfer rate of Cu in the treatment of NH4+-N from the underground to the aboveground was higher than that in NO3--N treated castor.The content of oxidizable Cu in soil treated with NH4+-N was higher than that of NO3--N treatment when N concentrations were same.2.When hydroponics,the effect of N treatments on Cu distribution in castor was not significant,root> stem and leaf.When the concentration of N was 75,150 and 300 mg/L,the contents of Cu in stems and leaves of the castor treated with NO3--N were 330.7,313 and 255.2 mg/kg respectively,which were significantly higher than those of NH4+-N treatemen.Cu content in the root decreased significantly with the increase of N concentration in both forms of N.The results of treatment at different times showed the stress degree in the leaf and root of the treated castor were similar on the second day after treated,but that in the NO3--N treatment was less than the NH4+-N treatment on the 6th day.3.In situ contaminated soil to add different concentrations of N,P fertilizer potted,the results showed that the chlorophyll content of castor leaves was increased by fertilization applying.The effects of different treatments on the biomass of castor was different.The highest biomass was 1.09 g,which was 181.6% of CK treatment,the lowest was 0.45 g,only 75.0% of CK.The different fertilization treatments affected the Cu content in the castor differently.The highest Cu content in the ground part of castor was 166.8 mg/kg,which was 236.3% of the CK,the lowest was 60.5 mg/kg,only 85.7% of the CK.In the stem,Cu content of up to 7.9 mg/kg,which was 210% of the CK,the lowest was 0.58 mg/kg,only 15.3% of the CK.Cu content of leaves up to 19.7 mg/kg,which was the 139% of CK,the lowest was 5.3 mg/kg,only 37.1% of CK.The soil pH was 0.2~0.4 units lower than that of the untreated soil.The content of organic matter in castor soil was 0.5~1.7 g/kg,which was higher than that of non-cultivated soil.The content of weak acid extracted and reducible Cu in Castor soil was about 10% higher than that in the non-cultivated soil,but there was no obvious change pattern in each fertilization treatment.