中文摘要：

【目的】研究不同水稻品种对土壤中镉（Cd）毒害的敏感性分布规律,测定基于保护95%水稻品种的土壤中Cd对不同水稻毒害的生态风险阈值HC5,为中国水稻Cd污染防治提供理论依据。【方法】利用中国南方具有代表性的两种水稻土,通过外源添加Cd制备成0、1.2、4.8、10、40、120 mg·kg-1的Cd污染土壤,以中国水稻主产区18个常规不同水稻品种为试材,通过温室盆栽试验测定不同Cd污染土壤对不同品种水稻的生物量、植株Cd含量及不同水稻Cd吸收的生物富集系数（BCF）影响。通过国际最新的累积概率分布函数逻辑斯蒂克分布模型（Log-logistic distribution）对不同水稻基于生物量的Cd毒性的剂量-效应关系进行拟合,利用物种敏感性分布模型Burr-III构建出Cd对不同水稻毒性的物种敏感度分布频次曲线（SSD）,并基于此推导出不同水稻Cd毒性的物种敏感性分布频次和基于保护95%水稻品种的Cd毒性阈值HC5,并测定不同水稻Cd吸收BCF值与土壤中Cd有效态含量变化的定量关系。【结果】在酸性祁阳红壤中,不同品种水稻随着Cd处理浓度的增加,生物量明显下降,对Cd最为敏感的品种X-42,生物量降低86%,而对Cd耐性较强的品种Z-120生物量降低51%。当添加浓度为4.8 mg·kg-1时,JY-253、J-463、Z-611、J-899、T-15、X-6、T-167品种水稻的生物量达到最大,其余品种均在1.2 mg·kg-1处理下达到最高。与对照相比,不同品种水稻的生物量增加了4%—56%,说明低剂量Cd对水稻生长有一定的刺激效应。在中碱性广州水稻土中,不同品种水稻随着Cd处理浓度的增加,生物量没有显著性差异。在两种土壤中,生物富集系数（BCF）随着Cd处理浓度的增加而降低,在低镉（1.2 mg·kg-1）条件下,红壤水稻BCF的变化范围为0.0056（S-974）—0.0133（T-15）,相差2.38倍；而广州水稻土的变化范围则为0.0018（L-42,LY-28）—0.0034（J-899）,相差1.89倍。但?

英文摘要：

【Objective】Understanding of the accumulation characteristics of Cadmium by different rice cultivars in soils and its species sensitivity distribution is necessary for determination of the hazardous concentration of Cd to rice cultivars of 5% of the tested species（HC5）, the threshold values（HC5） of Cd to rice species will provide vital information for protection of Cd pollution to different rice cultivars and thereafter the food chains in China.【Method】Two typical paddy soils were collected from southern China, and the soils were polluted by Cd with different Cd addition levels of 0, 1.2, 4.8, 10, 40, and 120 mg·kg-1 in soils. Eighteen different rice cultivars from the main rice producing areas around China were selected for test plant species in this study. The biomass of the rice cultivars, the Cd concentrations in plants and thereafter the bioconcentration factor（BCFs） were investigated using pot experiments in green houses. The log-logistic distribution model was used to determinate the dose-response relationship of Cd toxicity to rice cultivars based on different endpoints. The response relationships of Cd toxicity to18 different rice species were fitted by cumulative probability distribution functions Log-logistic distribution model. The species sensitivity distributions（SSD） of Cd to rice was performed with the Burr-III type distribution model, and the different species sensitivity distribution of Cd toxicity frequency and 95% of rice varieties based on the protection of Cd toxicity thresholds HC5 were obtained and meanwhile, the quantitative relationship of BCFs with the bioavailability of Cd in soils was also determined in this study.【Result】 The biomass of different rice species decreased with the increasing concentrations of Cd in acidic soil from Qiyang, biomass of rice X-42 which was the most sensitive species to Cd stress decreased by 86%, but the biomass of rice Z-120 showed stronger tolerance to Cd stress decreased by 51%. When added at a concentration of 4.8 mg·kg-1,