晚稻全生育期Cd的迁移转化规律及预测模型研究

为探讨晚稻全生育期Cd的迁移转化规律及预测模型,采用长沙市望城区大田试验土壤-水稻Cd点对点数据,对水稻4个典型生育期（苗期、分蘖期、灌浆期和成熟期）及不同部位（根、茎叶及籽粒）Cd的吸收、累积和分配差异进行研究。结果表明,同一生育期各部位Cd含量和富集能力均为根>茎叶>籽粒,且根部明显高于其他部位,不同生育期差异显著,具体为成熟期>灌浆期>分蘖期>苗期;Cd转运能力为土-根>根-茎叶>茎叶-籽粒>根-籽粒,籽粒Cd大部分来自于茎叶的转移,且分蘖期转运能力显著高于其余生育期;Cd积累量和分配差异为茎叶>根>籽粒,且分蘖期和成熟期远大于苗期和灌浆期;土壤pH和有效态镉(ACd)含量是影响水稻Cd吸收的主控因子,pH为负效应,有效态镉为正效应,分蘖期茎叶Cd含量受其影响最大,是控制Cd进入籽粒的关键时期。可利用分蘖期土壤pH和有效态镉含量预测成熟期籽粒Cd含量,最优预测模型为lgCd_{成熟期籽粒}=0.158-0.099pH_分蘖期+0.261lgACd_分蘖期。研究结果可为中国长株潭地区稻田土壤Cd污染风险评估和管控提供理论依据和数据支撑。

Study on the Migration,Transformation and Prediction Model of Cadmium in the Whole Growth Stage of Late Rice

To better understand the migration, transformation and prediction model of cadmium (Cd) in the whole growth stage of late rice, we used soil-rice point-to-point data of Cd in field test in Wangcheng Changsha to study the differences of absorption, accumulation and distribution of Cd in different parts (root, stem and leaf, grain) of rice and its four typical growth stages (seedling stage, tillering stage, filling stage and mature stage). The results indicate that the Cd content and enrichment ability of each part in the same growth stage are all the roots> stems and leaves> grains, and the Cd content in roots are significantly higher than that in other parts, and there are significant differences in different growth stages, namely mature stage> filling stage> tillering stage> seedling stage. The transport capacity of Cd is soil root> root-stem and leaf> stem and leaf-grain> root-grain, most of the Cd in grain is from the transfer of the stem and leaf, and the transport capacity of Cd in tillering stage is significantly higher than that in other stages. The accumulation and distribution differences of Cd are stem and leaf> root> grain, and the tillering stage and mature stage are much higher than seedling stage and filling stage. The main factors affecting the Cd absorption are soil pH and available cadmium (ACd) content, pH has a negative effect and available cadmium has a positive effect, and the Cd content in stems and leaves of tillering stage is most affected by them, therefore it is the key stage to control Cd into grain. The pH and available cadmium in tillering stage could be used to predict Cd content of grains in mature stage, and the optimal prediction model is lgCd_{the grain in maturity stage}= 0.158- 0.099pH_{tillering stage}+ 0.261lgACd_{tillering stage}. The research results could provide a theoretical basis and data support for the risk assessment and controlling of soil Cd pollution in rice fields in Changzhutan area of China.