水分状况对水稻镉砷吸收转运的影响

为探明不同水分状况下(淹水深度和潜水位高度)水稻对镉(Cd)、砷(As)吸收转运差异,采用盆栽试验,以湿润管理为对照,研究了3、6、9 cm的淹水深度和-3、-6、-9 cm潜水位高度下水稻对Cd、As吸收转运的影响。与湿润管理(CK)相比,淹水对水稻产量无显著影响,但低潜水位下的水稻产量比CK下降了21.06%~28.44%;淹水显著降低了水稻米、茎叶、根的Cd含量,但促进了根As的积累,淹水的稻米Cd含量比CK下降了61.11%~69.43%;而低潜水位处理则显著增加了水稻对Cd的吸收,但显著抑制了对As的积累,低潜水位处理的稻米Cd含量比CK增加了4.08~4.48倍,而稻米As含量比CK降低了79.20%~81.96%。Cd、As在土壤-水稻系统的迁移转运过程中,不同水分状态下水稻对Cd、As的积累主要取决于土壤至根系的迁移转运环节,且米As含量还受As在根系、茎叶、稻米中转运分配的调节。不同淹水深度或不同潜水位高度对水稻米、茎叶、根的Cd含量或As含量影响皆不明显,水稻对Cd、As的吸收主要受限于淹水的状态;相关分析结果表明,不同水分管理模式下,水稻对Cd和As的吸收积累呈极显著负相关。因此,在Cd、As污染土壤的水分管理过程中,应结合土壤Cd、As污染程度制定适当的水分管理策略。

Effect of water levels on cadmium and arsenic absorption and transportation in rice

To investigate the effects of water levels(water depths and phreatic water levels) on arsenic(As) and cadmium(Cd) absorption and transportation in rice, pot experiments with water depths of 3, 6, 9 cm and phreatic water levels of -3, -6, -9 cm were carried out. The results showed that different water levels above ground had no significant impact on rice yield. However, groundwater levels decreased the yields by 21.06%~28.44% when compared to wetness as the control(CK). Regarding Cd and As absorption and transportation, water depth greatly decreased the Cd contents in grain, stem, and leaves but promoted As accumulation in roots. For example, Cd content in grain decreased by 61.11%~69.43% compared to that in CK. However, groundwater levels increased Cd content by 4.08~4.48 times in rice grain, whereas it decreased As content by 79.20%~81.96% compared to that in CK. Under different water regimes, As and Cd transportation from soil to roots played a determinant role in As and Cd accumulation in rice. As and Cd contents in rice grains were also regulated by the transportation and distribution of As and Cd levels in roots, stems, and leaves. No significant differences in As and Cd concentrations among grain, stem, leaves, and roots were observed between different submergence depths or phreatic water levels. These results indicate that Cd and As absorption and accumulation were mainly limited by the two flooding forms. Correlation analysis revealed that there was a highly significant negative correlation between As and Cd levels in rice grain water depths. Thus, our results suggest that appropriate water management strategies should be used to combat high levels of As and Cd in rice grains from soil Cd and As pollution.