2种杂交水稻对2种不同土壤中Cd吸收与分配的比较

Comparison of Cd Uptake and Partitioning in Plant Tissues by Two Hybrid Rice Grown in Two Contrasting Paddy Soils

选择两种水稻(超级稻"Ⅱ优明86"和普通杂交稻"汕优63")与乌栅土和红沙泥田两种水稻土为材料,采用添加(2.5mgCd·kg-1土)和不添加外源Cd处理进行盆栽试验,研究了不同杂交稻品种在不同生育期对Cd的吸收及其器官分配。结果表明,抽穗期是杂交稻和超级稻Cd吸收的关键时期,且Cd处理下超级稻品种Cd吸收能力高于普通杂交稻品种。无外源Cd处理下,超级稻品种比普通杂交稻品种表现出更高的转运能力,因而是转运和器官分配特点而不是吸收Cd能力决定两者的子粒Cd水平。不过,在外源Cd处理下,土壤因素成为超级稻子粒Cd含量高于杂交稻的主要因素,超级稻在Cd化学有效性高的红沙泥田中的Cd吸收能力显著高于普通杂交稻,这可能是我们以前报道的酸性红壤水稻土中杂交稻子粒Cd吸收积累成倍增加的主要原因。

Growing of hybrid rice cultivars are increasingly extended in South China for high rice production. However, much attention has been paid to the higher Cd uptake and grain accumulation by the hybrid rice than the conventional rice for the last 5 years. To understanding the possible mechanism for the enhanced Cd uptake by hybrid rice cultivars, a pot experiments were conducted with two rice cultivars （a super hybrid rice and a common hybrid rice） on two different soils with and without Cd spiking （2.5 mg Cd·kg^-1 soil） to soils. The uptake and partitioning of Cd by rice was determined with atomic adsorption spectroscopy（AAS） at different growth stages. The results showed that on the basis of total biomass construction, the most intense active Cd uptake for both hybrid rice cuhivars happened at the heading stage. Compared to common hybrid rice cultivars, Cd uptake by super rice ones was much enhanced under Cd spiking. While super rice cultivars had a higher capacity to translocate and partition Cd to grains than the common rice under no Cd spiking. That is, under no Cd pollution, the Cd translocation and partitioning drive the grain Cd level by the rice cultivars. However, with spiked Cd, soil factor may become significant in controlling the Cd availability as super rice had Cd uptake in grains as several folds as common rice cuhivars when grown in an acidic soil. This explained intense enhanced Cd uptake and accumulation in rice grains by hybrid rice cultivars grown in red soil region from South China as reported in previous studies.