【作者】 龚伟群；

【导师】 潘根兴； 李恋卿；

【作者基本信息】 南京农业大学 ， 土壤学， 2006， 硕士

【摘要】 由于工业污染、污水灌溉、污泥施用以及施肥等原因，我国农田土壤Cd污染问题日趋严重，对我国的食物安全和生态安全构成了严重的挑战。许多研究表明，通过土壤-作物-食物系统的迁移是人类摄取Cd的主要途径。水稻是我国的重要粮食作物，稻米是我国人民传统的主要食物来源。当前，杂交水稻是我国水稻生产的主要栽培品种。为了保障粮食安全供应，我国正在推广单产达9t·hm^-2以上的超级稻。然而许多研究表明，水稻籽粒对土壤Cd吸收在大宗农作物中是最强的，在工矿污染条件下甚至可能产生“镉米”，严重危害人类健康。 尽管当前研究同种条件下不同水稻品种或基因型对Cd吸收影响的文献较多，但还不足以说明田间条件下土壤与品种两者之间的交互作用对水稻Cd的吸收积累及其对食物安全的影响。本课题组已研究报道了土壤-品种交互作用可使常规稻对Cd的吸收积累达到严重的安全风险程度，但还不清楚这种土壤-基因型交互作用对杂交水稻尤其是超级稻的Cd吸收和籽粒积累的影响如何。因此，本研究选择2种杂交水稻（普通杂交稻“汕优63”和超级稻“Ⅱ优明86”）与乌栅土和红沙泥田2种不同性质水稻土为材料，采用外加Cd（2.5mgCd／kg土）和不外加Cd处理进行盆栽试验，研究了水稻对土壤中Cd的吸收及籽粒积累特点。 结果表明，杂交水稻对Cd的吸收及籽粒积累依土壤、品种及二者的交互作用而变化。杂交稻对土壤中原有Cd的吸收与积累，基因型影响高于土壤类型的影响，但对外源Cd的吸收与籽粒积累，土壤类型的影响强于品种基因型；而土壤与品种间的正交互作用（Cd吸收强的超级稻种植于土壤Cd化学有效性高的红沙泥田）可使水稻籽粒Cd积累成倍提高。说明在未污染条件下，杂交稻对Cd的吸收与籽粒积累主要受品种的吸收能力控制，而在污染条件下，土壤化学性质对Cd有效性的影响成为土壤-水稻系统Cd迁移的主要控制因素。 从食物安全风险考虑，在酸性土壤中或污染条件下，超级稻对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。加Cd处理下，汕优63中Cd滞留于根部，而Ⅱ优明86则有较强的将Cd向上运输的能力。计算表明，Ⅱ优明86籽粒Cd积累的不利效应远远超过其产量的增加效应。 本实验结果还显示，土壤-水稻系统中Cd的迁移与籽粒积累受到品种及基因型、土壤化学条件、Cd污染水平以及土壤-品种的相互作用的影响，与常规稻相比，高产更多还原

【Abstract】 Cd pollution of croplands of China has been shown intensified due to the increasing Cd loading from industrial contamination, sewage water irrigation, application of sewage sludge and Cd-containing fertilizers, which poses critical challenge for food security and ecological safety of China. Cd translocation through soil-food crop-diet is generally considered as one of most important pathways for human Cd exposure. Rice is a major source of Chinese food and rice grain has been traditionally consumed as a dormant daily food. Hybrid rice cultivars are extensively cultivated and super rice cultivars with potential yield over 9 t per ha are being extended in rice areas of South China. However, rice has been considered as a particular crop with high Cd uptake and accumulation in grains among the main food crops and Cd-accumulated rice could be resulted from severe Cd pollution araising serious health concerns for Chinese subsistence diet farmers.Knowledge about Cd uptake by hybrid rice and the potential health risks is still insufficient especially the interactive effect of paddy soils and cultivars under field soil conditions although there have been a number of studies on genotype effect on Cd uptake and grain partitioning. In previous studies, it was clearly demonatrated that the uptake of Cd and accumulation in grains could reach a serious level of health risk of non-hybrid cultivars under interaction of genotype and soil types. How such interaction affects Cd uptake and health risk by hybrid rice or super rice is still unknown. In this study, a pot experiment was conducted to elucidate mutual interaction of soil and cultivars on uptake and grain accumulation of Cd by hybrid rice with or without Cd spiking at 2.5mg·kg^-1 under continuous submerging condition. Two hybrid rice cultivars （Shanyou 63, a common hybrid rice and Ⅱ Youming 86, a super-rice） and two paddy soils （a Wushantu, a Gleyic Stagnic Anthrosols and a Hongshanitian, an Ultic Stagnic Anthrosols） were used.The main results were as follows:Significant differences were observed in Cd uptake and grain partitioning between soils, cultivars and the soil-cultivar interactions. The cultivars effect on uptake of更多还原