不同浓度锌处理下水稻幼苗对镉的累积效应

为探究锌（Zn）对水稻镉（Cd）累积的影响及其根表铁膜所发挥的作用，选取Cd高累积型水稻品种中9优547（简称"Z547"）和Cd低累积型水稻品种金优402（简称"J402"），采用温室水培试验，研究0、2、5、10、15和20 μmol/L等6个Zn浓度下水稻幼苗对Cd的累积效应，以及不同浓度Zn处理对根表铁膜生成量的影响.结果表明:①随着c（Zn）的增加，Z547和J402水稻幼苗生物量均呈先增后减的趋势，分别在c（Zn）为2和10 μmol/L时达到最大值.②Z547和J402水稻幼苗中w（Cd）均呈先降后增的趋势，分别在c（Zn）为5和2 μmol/L时达到最小值；当水稻幼苗中w（Cd）达到最小值时，Z547根和地上部中w（Cd）分别为31.65和11.47 mg/kg，J402根和地上部中w（Cd）分别为22.58和14.36 mg/kg.③不同浓度Zn处理下水稻幼苗各部位中w（Cd）均与根表铁膜中w（Mn）、w（Fe）、w（Fe+Mn）呈显著正相关，高铁膜处理水稻幼苗中w（Cd）显著高于低铁膜处理，表明根表铁膜生成量的增加会促进Cd在水稻幼苗中的累积.研究显示，当c（Zn）较低时，c（Zn）的增加会抑制水稻幼苗对Cd的累积；当c（Zn）较高时，c（Zn）的增加会促进水稻幼苗对Cd的累积，而Zn可通过控制根表铁膜的生成来影响水稻幼苗对Cd的累积. 

Accumulation of Cadmium in Rice Seedlings After Treatment with Different Concentrations of Zinc

High Cd accumulation cultivar 'Zhong 9 you 547 (Z547)' and low Cd accumulation cultivar 'Jinyou 402 (J402)' were chosen as the model plants and hydroponics culture experiments were carried out in greenhouse to study the effects of different concentrations of Zn on the accumulation of Cd in rice seedlings and the concentrations of iron plaque. The results showed that in the range of 0-20 μmol/L Zn, the biomass of rice seedlings reached the maximum values when the concentrations of Zn were 2 (Z547) and 10 μmol/L (J402), respectively, and then decreased with the increasing concentrations of Zn. As Zn concentration increased, the concentrations of Cd in rice seedlings first decreased and then increased. The minimum concentrations of Cd in root and shoot of Z547 were 31.65 and 11.47 mg/kg, respectively, at 5 μmol/L Zn. The minimum concentrations of Cd in root and shoot of J402 were 22.58 and 14.36 mg/kg, respectively, at 2 μmol/L Zn. As a result, the presence of different concentrations of Zn could significantly affect the accumulation of Cd in rice seedlings. The concentrations of Cd in rice seedlings treated with high iron plaque were much higher than that treated with low iron plaque, which indicated that higher concentrations of iron plaque on root surface would promote the accumulation of Cd in rice seedlings. At different concentrations of Zn, the concentrations of manganese (Mn), iron (Fe) and Mn+Fe in iron plaque were positively correlated with the concentrations of Cd in rice seedlings. The results indicated that Zn could affect the accumulation of Cd in rice seedlings by changing the formation of iron plaque.