【作者】 柯庆明；

【导师】 林文雄；

【作者基本信息】 福建农林大学 ， 持续发展与推广学， 2006， 博士

【摘要】 目前，我国已有大量农田受到有毒重金属的污染，这不仅影响作物生长和发育，降低产量与品质，并经作物吸收由食物链进入人体，对人类健康产生巨大威胁。因此，降低作物食用部分的有毒重金属含量具有重要的现实意义，尤其是水稻，它是我国也是全球最重要的粮食作物。水稻对一些有毒重金属的吸收、积累以及耐性存在显著的基因型差异，因此筛选和培育籽粒有毒重金属积累低且对重金属耐性较强的品种，不仅是可能的，也是在轻、中度重金属污染土壤上持续生产安全稻米的一条经济、有效的途径。同时，水稻对有毒重金属的吸收也受土壤重金属有效性的影响，而土壤重金属有效性与环境因子密切相关。但目前有关水稻有毒重金属积累的基因型与环境效应及其机理尚不清楚，从而限制了相关育种和栽培工作的开展。本研究在前期预备试验和研究工作基础上，以我国稻米重金属污染较为严重的Cd为研究对象，研究了水稻籽粒中Cd积累的基因型与环境互作效应，筛选到若干个籽粒Cd含量低的基因型，并探索了水稻Cd耐性和低积累基因型的筛选方法及其Cd胁迫对水稻生长与营养代谢的影响。主要研究结果如下： 1、水稻抗Cd胁迫的种质资源筛选 采用水培营养液加镉法，对七十二个水稻品种（系）进行不同抗性水稻种质资源的筛选。试验结果表明，供试的七十二个水稻基因型的耐镉胁迫能力存在极显著差异，依据0.2mg／LCd处理下的Cd耐性指数可将72个基因行聚成Cd敏感基因型、较敏感基因型、耐-Cd基因型、较耐基因型。其中以Lement、IR98-22、兰贝利、F₆-143-1、F₆-138-1、玉米粳5号、R669等耐性最强，Dular等对镉胁迫最敏感。研究结果还表明，水稻各器官Cd含量随Cd处理水平和生育进程而增加，且吸收的Cd主要积累在根系，Cd在水稻各部位中的分布规律为：根＞茎＞鞘＞叶＞稻米。在8mg／Kg Cd处理下，品种Dular稻米中Cd含量超标，而品种Lement稻米中未检出，进一步验证Cd胁迫下Lement的耐性比Dula高，这与前期的筛选结果一致。 2、水稻抗Cd胁迫的生理生化特性研究 以耐性不同的两个水稻品种（Lement，低累积型和Dular，高累积型）为材料，研究了镉胁迫对水稻植株生长和抗氧化酶系统的影响。采用水培试验，Cd处理设0、50更多还原

【Abstract】 At present, a huge area of arable land in China has been contaminated by toxic heavy metals, which not only inhibits the growth and development of crops, leading to reduced yield and quality, but also poses a great threat to human health via food chain due to uptake by crops .It is, therefore, imperative to reduce toxic heavy metal concentrations in edible parts of crops, particularly in rice, which is one of the most frequently consumed cereals worldwide. The uptake, accumulation of and tolerance to some heavy metals vary greatly among plant species and among genotypes within a species. In rice, a significant difference also exists among genotypes in heavy metal concentrations in grains and their tolerance, thus providing a possibility of developing rice cultivars with high tolerance and low grain accumulation of toxic heavy metals.It is considered the most economic and efficient approach to reduce heavy metal concentrations in rice grains planted on the slightly or moderately contaminated soils. Meanwhile, heavy metal uptake and accumulation by crops is a function of the complex interaction of plant, soil, environmental and cultivated factors that affect bioavailability of heavy metals in soil. Up to date, however, the genotypic and environmental variation of toxic heavy metal concentrations in rice grains and its mechanism remain poorly understood ,thus hindering the progress of breeding and agronomic improvement in heavy metal tolerance and accumulation in grains, the present experiments were carried out to study the genotypic and environmental variation Cd concentrations of rice grains and to screen out some since genotypes with low Cd concentrations in grains, focusing on the most widespread and severe Cd in Southeast of China. Meanwhile, the approaches of identifying the rice genotype with distinct Cd-tolerance, and accumulation, and the effects of Cd on rice growth and nutrition metabolism were also studied. The main results are as follows:1 Studies on screening of rice (Oryza sativa L.) germplasm tolerant to Cd stress72 rice cultivals were screened with different Cd tolerance by adding Cd in the hydroponic culture nutrition. The results indicated that a significant genotypic variation of Cd tolerance in the tested 72 cultivars. A cluster analysis of tolerance indices, including shoot height and weight, root length and weight of the plants exposed to 0.2mg/L Cd level,更多还原