低镉累积水稻品种的筛选方法研究——品种与类型

Breeding Rice Cultivars with Low Accumulation of Cadmium:Cultivars Versus Types

选择6种水稻(Oryza sativa L.)(2种常规稻,2种两系杂交稻,2种三系杂交稻,其中均有1种为超级稻)以及上坝镉污染水稻土为材料,采用全生育期淹水和水稻抽穗后排水处理进行盆栽试验,研究了低Cd水稻品种按品种和类型筛选的可行性。结果表明,水稻品种间存在显著差异。水稻对Cd的吸收及籽粒积累依水分管理和品种而变化,水分管理影响远远高于基因型影响。在两种水分管理中,水稻品种间精米Cd含量的排名顺序基本一致,从而表明在低污染水平土壤上,水稻对Cd的累积品种间存在一定的稳定性。而水稻类型间Cd含量没有显著差异,因此按照水稻类型来筛选是不可行的,应针对品种来筛选并对筛选出来的稳定的品种进行重点研究。抽穗后排水处理的水稻对Cd的吸收与籽粒积累十分强烈,就地消费人群的籽粒Cd暴露风险水平达到数倍于临界摄入剂量水平。因此,在Cd污染土壤中栽培必须考虑水分管理对水稻吸收Cd的影响与籽粒Cd的暴露风险。

A pot experiment was couducted with 6 rice genotypes in the spring of 2008 to study the feasibility of selecting or breeding rice eultivars with constantly low accumulation of Cd based on cuhivars and types. All the rice genotypes were grown within two different water managements, under continuous submerging condition（ 2-3 cm ）and pot drainage from heading to harvest stages. The results showed that cadmium（ Cd ）concentrations varied among cultivars, and the order of Cd concentrations almost identical for both submerged and drainage treatments, indicating that screening eultivars for low levels of Cd concentrations in rice grains are a practical method to control the food chain pollution. Both water management patterns and different euhivars had remarkably influenced the concentrations of Cd in rice grains, and characterized that the contribution of water management to the total variation was much larger than the genotype factor, indicating that the predominance of water management was related to the grain Cd concentration. The selection by rice types did not work out as there were no significantly differences between the types. It is suggested that in order to control the human Cd exposure by diet, an appropriate water management approach under the continuous submerging condition, especially at the later stages of rice growth where soils are polluted with Cd, and a combination of rice varieties of low Cd in rice grains with effective water management, would produce safe rice grains in low-level Cd polluted soils.