农艺调控措施对水稻镉积累的影响及其机理研究

利用盆栽试验研究了低镉积累品种种植(V)、全生育期淹水灌溉(I)和施用生石灰调节土壤pH值(P)3种农艺调控措施及其组合对河沙泥田中镉植物有效性的影响及其机理。结果表明:不同农艺措施使土壤的pH值提高0.05~0.9个单位,土壤NH₄OAc提取态镉含量降低5.1%~38.4%,水稻地上部镉含量显著降低。这3种措施组合(VIP)降低水稻吸收与累积镉的效果最佳,IP、PV次之;与对照相比,VIP处理糙米镉含量降低了61.5%,稻壳镉含量降低了70.9%。采取农艺调控措施处理不但可以有效降低水稻地上部分镉含量,而且能提高水稻产量,以VIP处理效果最佳,是对照的2.6倍。因子分析结果显示,低镉积累水稻品种种植和土壤pH值提高可有效降低糙米镉的积累,全生育期淹水与土壤pH值提高之间存在显著交互作用。可见,种植低镉积累品种结合土壤pH值调节和淹水灌溉对镉污染稻田的修复治理具有重要意义。

Effects of Agronomic Measures on Accumulation of Cd in Rice

Research has shown that agronomic measures could decrease soil Cd availability and thus reduce Cd uptake by plants. In this research, the effects of low Cd-accumulating rice variety(V), soil pH adjustment(P), continuous flooding(I) and their combinations on Cd phytoavailability in paddy soil were investigated on an alluvial sandy soil in a pot experiment. Different agronomic practices increased soil pH by 0.05 to 0.9, but decreased NH₄OAc extractable Cd by 5.1% to 38.4%, as compared with the control(CK). The treatment with V-I-P significantly reduced the content of Cd in brown rice and rice hull by 61.5%(P< 0.01) and 70.9%(P< 0.01) over the control, respectively. Both IP and PV treatments had less effects. The yield of rice grain was increased by those agronomic measures, with the most noticeable yield increases observed in the VIP treatment 2.6 time as much as the control. Planting low Cd-accumulating rice variety(P< 0.05) and adjusting soil pH(P< 0.001) significantly lowered Cd concentrations in brown rice. In addition, a significant interaction between continuous flooding and soil pH was observed(P< 0.01). The present results suggest that combination of low Cd-accumulating rice variety, soil pH adjustment and continuous flooding could control Cd absorption by rice in contaminated paddy soils.