砷污染土壤中不同基因型水稻根表铁膜的形成及其对砷吸收和转运影响

采用土壤盆栽试验法，研究6个不同基因型水稻品种根表铁膜形成及其对As吸收、转运的影响。结果表明，水稻形成根表铁膜在不同基因型品种之间差异显著（p<0.001），其中品种94D-22形成铁膜量（以Fe含量计）是品种圭630的1.5~1.8倍，添加As处理对水稻根表铁膜形成影响不显著。低As含量的对照土壤中，水稻根表铁膜量与根系As含量存在着显著的正相关关系（r=0.657，n=24，p<0.01），与As转移系数呈显著的负相关关系(r=-0.612，n=24，p<0.01）。土壤添加As后，水稻根表铁膜量与茎叶As含量存在显著的正相关关系（r=0.653-0.673，n=24，p<0.01），与As转运之间无显著相关性。比较生长于As污染土壤的不同水稻品种，科优1360茎叶积累As较少，且其根系转运As能力也较差，而品种94D-22正好相反。研究结果表明，在As含量较低的土壤中，水稻根表铁膜的存在可成为根系As的障碍层，阻止As向地上部转运；但在As含量较高的土壤，根表铁膜的存在却促进了水稻茎叶对As的积累，其对As的转运没有显著影响。人们可通过作物品种筛选来防治土壤As污染危害、降低As对人体健康的威胁。

Genotypic Differences in Iron Plaque Formation on Root Surface and Their Effect on Arsenic Uptake and Translocation in Rice (Oryza sativa L.) Grown in Arsenic Contaminated Soil

The formation of iron plaque on root surface, arsenic uptake and translocation by different genotypic rice (Oryza satival L.) were investigated in pot experiments. The results showed that the formation of iron plaque on root surface between genotypes was significantly different (p<0.001), Fe concentration in iron plaque for 94D-22 was 1.5-1.8 times of that for Gui630. Addition of As had no significant effect on iron plaque formation. At low content of As soil, there was a significant positive correlation between the amount of iron plaque and As concentration in roots (r=0.657, n=24, p<0.01). Significant negative correlation was between the amount of iron plaque and translocation factor (TF) (r=-0.612, n=24, p<0.01). There was a significant positive correlation between the amount of iron plaque and As concentration in shoots (r=0.653-0.673, n=24, p<0.01), and no significant correlation between the amount of iron plaque and translocation factor (TF) after As was added into soil. Keyou1360 had lower As concentration in shoots and translocation factor (TF), and 94D-22 showed opposite results among the six genotypes. The results indicated that iron plaque on root surface acted as a barrier to As translocation within rice plants at low As level, while increased As accumulation in shoots and did not significantly affect As translocation from root to shoot at high As level. Hazards of As contaminated soil and health risk could be decreased through cultivars screening.