镉处理根表铁膜对水稻吸收镉、锰、铜、锌的影响

摘要

本试验利用营养液和土壤培养系统，研究不同Fe、Cd处理下根表铁膜对水稻吸收Cd、Mn、Cu、Zn的影响。土壤中Fe的水平为0、1、2 g/kg Fe（以FeSO4·7H2O的形式供应），Cd的水平为0、2、10 mg/kg Cd（以3CdSO4·8H2 O的形式供应）。营养液中Fe和Cd的水平分别为0、10、30、50、80、100 mg/L Fe和0、0.1、1.0 mg/L Cd。收获后测定水稻根表、根中和地上部Cd、 Fe、 Mn、Cu、Zn含量。试验结果表明，两种培养方式下，随着介质中Fe浓度的增加，水稻根表铁膜（ DCB-Fe）逐渐增多。土壤培养方式下，根表铁膜中Cd和Mn含量随铁膜量增加而略有增加，所有元素含量均表现为根中大于铁膜中。营养液培养条件下，根表铁膜中Mn和Cu含量在高量Fe供应时有所增加， Mn、Cu、Zn表现为铁膜中大于根中。根表铁膜中Zn含量在两种培养方式下均未呈现一定规律性变化。根中和地上部Cd、Mn、Cu、Zn含量一般都随介质中Fe浓度的增加而下降，Cu和Zn含量在加Cd处理中下降。以上结果证明，铁膜对Cd的吸附阻挡能力有限，对Mn、Cu、 Zn的吸附作用因培养方式和元素种类不同而有所差异，植株体内微量元素含量的下降主要与它们之间的相互抑制作用有关。%In this study , soil and hydroponics culture systems were used to investigate the effects of iron plaque on the uptakes of Cd , Mn, Cu and Zn by rice seedlings supplied with different levels of Fe and Cd .The three iron levels(as FeSO4· 7H2O) were 0, 1 and 2 g/kg in soil culture, and the six levels were 0,10,30,50,80 and 100 mg/L in solution culture.The cadmium levels(as 3CdSO4· 8H2O) were 0,2 and 10 mg/kg in soil, and 0,0.1 and 1.0 mg/L in solution.After harvest, the contentrations of Fe , Cd, Mn, Cu and Zn in iron plaque, roots and shoots were determined.The results showed that the iron plaque (Dithionite-Citrate-Bicarbonate DCB-Fe) on root surface was increased with the increase of Fe concentration in the two culture systems .In the soil culture experiment , the Cd and Mn contentrations in the iron plaque ( DCB-Cd and DCB-Mn) are slightly increased with the increase of external Fe , and the concentrations of all elements in roots are higher than those in the iron plaque .In the hydroponics culture experiment , the Mn and Cu contentrations in the iron plaque are increased only when higher Fe is added, and the contentrations of Mn , Cu and Zn in the iron plaque are higher than those in roots .The contentrations of Zn in iron plaque are not significantly changed in both soil and hydroponics culture experiments . In general, the concentrations of Cd , Mn, Cu and Zn in roots and shoots are decreased with the increase of Fe supply in soil and nutrient solution , and the concentrations of Cu and Zn in the Cd-addition treatments are lower than those in the no Cd-addition treatments.The above results indicate that the iron plaque may play a limited role in Cd uptake and its translocation in rice plants , and the effects of the iron plaque on the uptakes of Mn , Cu and Zn depend on the culture systems and elements species .However, antagonistic interaction between elements probably contributes to the decreases of the concentrations of Cd , Mn, Cu and Zn in roots and shoots .