水稻籽粒发育过程中各器官镉积累量的变化及其与基因型和土壤镉水平的关系

以镉（Cd）积累潜力不同的2个籼稻品种为材料,研究了籽粒发育过程中各器官中Cd含量的动态变化及其与土壤中Cd含量的关系。结果表明,在含Cd的生长环境中,水稻根系中的Cd含量在整个生育期中保持稳定增长的趋势,而茎叶、穗轴和稻壳等器官在营养生长阶段积累了大量的Cd,然后在籽粒充实过程中向外输出,其中旗叶和稻壳中的Cd输出率在50%以上,明显高于其他营养器官。根系和叶片中的Cd含量与土壤中的Cd含量呈高度线性相关,茎秆和籽粒中的Cd含量与土壤中的Cd含量呈抛物线相关,说明根系、茎秆、叶片等营养器官对Cd有储存和“过滤”作用。低积累品种‘X24’穗轴中的Cd含量明显低于高积累品种‘T705’,说明营养器官中的Cd向籽粒中转运的速率是决定籽粒中Cd积累量的关键因素。但是,只有当土壤中的Cd含量为0.3~1.2 mg＆#183;kg-1时,低积累品种精米中的Cd含量才会显著低于高积累品种；当土壤中的Cd含量高于2.4 mg＆#183;kg-1时,2个品种精米中的Cd含量没有显著差异。

Changes in Cadmium Accumulation in Rice Organs during Grain Develop-ment and Their Relationship with Genotype and Cadmium Levels in Soil

Two indica rice （Oryza sativa） genotypes with different Cd accumulation potential were used to study the dynamic changes of Cd concentration in organs during grain developmental stage and their relation-ship with Cd levels in soil. Experimental results showed that rice root maintained a steady increase trend in Cd concentration during the rice life cycle. Other organs, i.e. stem, leaves, rachis and hull, accumulated a lot of Cd during vegetative growth stage and exported some of Cd during grain iflling period. More than 50%of Cd in lfag leaf and hull was exported out at reproductive stage. Low-Cd-accumulation （LCA） variety‘X24’ displayed apparently lower Cd content in rachis than high-Cd-accumulation （HCA） variety‘T705’. It indicated that Cd transport rate from vegetative organs to grains was the key factor limiting Cd accumulation in rice grains. How-ever, Cd content in polished rice of LCA variety was only signiifcantly lower than that of HCA variety when rice was planted in the soil containing Cd 0.3-1.2 mg＆#183;kg-1. When contaminated Cd in soil was above 2.4 mg＆#183;kg-1, the Cd accumulation in polished rice of LCA variety was similar to that of HCA variety.