EDDS对土壤铜镉有效性及蓖麻吸收转运的影响

为探究螯合剂对植物吸收重金属的影响，以蓖麻（Ricinus communis L.）为供试植物，通过土培和盆栽试验，研究不同含量乙二胺二琥珀酸（EDDS）对土壤中铜镉形态和植物吸收、转运的影响.结果表明，EDDS显著增加了土壤有效态铜和镉含量，培养15 d时，增幅分别为43.01%~103.55%和51.78%~69.43%，同时促进了可还原态铜向弱酸提取态转化，增加了土壤铜的移动性.EDDS促进了蓖麻对铜的吸收、转运与富集.EDDS 2.5和EDDS 5.0处理时，地上部铜含量是对照的4.88倍和16.65倍（P< 0.05），根部是对照的2.89倍和3.60倍（P<0.05），铜转运系数显著提高了72.73%和381.82%.EDDS 5.0处理时，蓖麻地上部和根部的铜提取量分别是对照处理的14.08倍和2.16倍，总铜提取量是对照处理的4.70倍（P< 0.05）.此外，EDDS显著增加了蓖麻镉含量，EDDS 2.5处理时，地上部和根部分别增加了15.15%和57.42%，蓖麻总镉提取量显著提高了13.44%.综上可知，EDDS能增加土壤铜镉的有效性，促进蓖麻对铜镉的吸收，提高蓖麻的修复效率，其中5.0 mmol·kg^-1 EDDS更有利于蓖麻对铜的提取，而2.5 mmol·kg^-1 EDDS处理对镉的提取有较高的增加效果.

Effect of EDDS Application on Soil Cu/Cd Availability and Uptake/transport by Castor

To investigate the effect of chelating agents on plant uptake of heavy metals, castor (Ricinus communis L.) was used as the test plant. Soil culture and pot experiments were conducted to study the effects of different concentrations of ethylenediamine disuccinic acid (EDDS) on the forms of Cu and Cd in soil and their absorption and transport by castor. The results showed that the application of EDDS significantly increased the content of available Cu and Cd. After 15 days of cultivation, the available Cu and Cd concentrations in the soil increased by 43.01%-103.55% and 51.78%-69.43%, respectively. EDDS promoted the conversion of reducible Cu to weak acid extractable and increased the mobility of Cu. Meanwhile, the application of EDDS promoted the absorption, transport, and enrichment of Cu in castor. Under the application of 2.5 mmol·kg^-1 EDDS and 5.0 mmol·kg^-1 EDDS, the Cu concentrations in the shoots were 4.88 times and 16.65 times higher than that of the control (P< 0.05), and the Cu concentrations in the roots were 2.89 times and 3.60 times higher than that of the control (P< 0.05), respectively. The Cu transport coefficient significantly increased by 72.73% and 381.82% when treated with EDDS 2.5 and EDDS 5.0. Simultaneously, the phytoextraction of Cu in shoots, roots, and their sum were 14.08, 2.16, and 4.70 times higher than that of the control (P<0.05), respectively, when treated with EDDS 5.0. Furthermore, EDDS significantly increased the Cd concentrations in castor. When treated with EDDS 2.5 the shoots and roots increased by 15.15% and 57.42%, respectively, and the phytoextraction of total Cd significantly increased by 13.44%. Generally, the EDDS treatment could increase the available Cu and Cd in soil, promote the uptake of Cu and Cd, and improve the phytoremediation efficiency of castor. Among them, the addition of 5.0 mmol·kg^-1 EDDS had the best effect for Cu, whereas the addition of 2.5 mmol kg^-1 EDDS had a higher increase in the phytoextraction of Cd.