水分管理对重金属在水稻根区及在水稻中积累的影响

Accumulation of heavy metal in rhizosphere of rice and their uptake in rice with different water managements

选取了酸性矿山废水污灌区重金属污染水稻土,通过盆栽试验,研究了不同水分管理条件(60%最大田间持水量,80%最大田间持水量,最大田间持水量,前期淹水+抽穗扬花期烤田,全生育期淹水)下水稻根际土壤及其不同器官(稻根、茎叶和籽粒)中As、Cd、Cu和Zn的含量变化。结果表明:土壤水分含量对水稻根际土壤中As、Cu和Zn的含量影响不大。但显著影响水稻不同器官对这3种元素的吸收积累。随着土壤水分含量的增加,水稻根、茎叶和籽粒中As的含量都显著增加;Cu的含量则逐渐减少;水稻茎叶中Zn含量也逐渐减少,但水稻根和籽粒中Zn含量则变化不明显。抽穗扬花期拷田能显著降低As在水稻中的积累,显著增加水稻茎叶中Zn的积累;但不影响水稻各器官中Cu,以及水稻根和籽粒中Zn的含量。此外,虽然这3种重金属在土壤中含量均超标,但在水稻籽粒中含量只有Zn全部超标,而Cu则都不超标,因此,农作物的超标情况并不直接与土壤的重金属超标相联系。

In this study the distribution of As, Cu and Zn in the rhizosphere and their uptake in rice （Oryza sativa L. cv. Choukoukoku） were investigated using paddy soil which was contaminated by acid mine drainage under five water-management treatments of 60%, 80%, 100% field moisture capacity （FMC）, flooded throughout the entire rice growth period and flooded followed by keeping 80%FMC after heading-flowering period.The water managements had no significant influence on the As, Cu and Zn concentrations in rhizosphere soil in maturity stage. However, the uptake of As, Cu and Zn in rice was obviously related to water managements. The increase of soil moisture enhanced the uptake of As, but decreased the uptake of Cu in different organs of rice （roots, stems and leaves, grains） and the uptake of Zn in the stems and leaves. Aerobic treatment after heading-flowering period declined As uptake in different organs of rice, but enhanced Zn uptake in stems and leaves and did not influence the uptake of Cu in rice. Furthermore, the results suggested that rice contained Zn concentration higher than Chinese standard maximum limits and flooded management enhanced As concentration in rice, which indicated that Zn and As were as potential sources of dietary heavy metals for Chinese consumers.