【作者】 李鹏；

【导师】 葛滢； 吴龙华；

【作者基本信息】 南京农业大学 ， 环境科学， 2011， 硕士

【摘要】 水稻是我国的第一大作物,近年来,随着工农业的迅速发展,农田土壤镉(Cd)污染日趋严重,严重影响着稻米的产量和质量安全。水稻对Cd的吸收与分配存在着品种差异,因此,探明Cd在不同品种水稻籽粒中累积的机理,有助于选育籽粒低Cd累积水稻品种。利用农艺措施调控Cd污染土壤上水稻对Cd的吸收是Cd污染土壤稻米安全生产的热点,而水分管理方式可以有效调控土壤Cd活性进而调控水稻对Cd的吸收,尽管关于不同水分管理对水稻Cd吸收和累积的影响机理的研究已有报道,但田间不同水分管理模式下水稻的Cd吸收积累的特征及机理则鲜有研究。本文采用水培、盆栽试验,选用Cd高、低吸收特性的不同水稻品种,探讨不同水稻品种糙米Cd累积的差异及机理,并通过盆栽及田间试验探讨了不同水分管理方式对水稻Cd吸收累积的影响及生理机制。主要研究结果如下：1.两种不同籽粒Cd含量水稻品种的镉吸收转运及其生理效应差异研究以两种籽粒Cd含量不同的水稻品种为材料,采用水培和盆栽试验,研究了水稻不同生育期Cd吸收特性、水稻生理性状及其与水稻糙米Cd含量的相互关系。盆栽试验结果表明,在含Cd量为1.57 mg kg-1的土壤上,中香1号(A16,低Cd品种)和IR65610-38-2-4-2-6-3(A54,高Cd品种)糙米中Cd含量分别为0.31和0.88 mg kg-1;尽管水培和土培试验均显示苗期A16对Cd的吸收转运强于A54,但在苗期之后的生育期内,A54吸收Cd的强度均高于A16；比较不同生育期两品种单株Cd累积量,发现苗期至拔节期的增幅最大,这一阶段是水稻吸收和分配Cd的重要时期；分析各生育期两个品种水稻地上部和根中Cd含量、根部向地上部的Cd转移率以及可以钝化滞留Cd的非蛋白巯基(NPT)含量,发现A16和A54的籽粒Cd含量差异可能是由根系吸收及向地上部转运等过程共同控制。2.盆栽试验条件下不同水分管理方式对水稻镉吸收与分配的影响及机理初探采用盆栽试验,研究了淹水、间歇灌溉及旱作三种水分管理方式对水稻苗期生长及Cd吸收累积的影响,并从土壤有效态Fe、有效S,水稻根表铁胶膜及水稻根和地上部的丙二醛含量、非蛋白巯基含量及过氧化物歧化酶活性等角度探讨了不同水分管理方式对水稻Cd吸收累积的影响机理。结果表明,淹水极显著地降低了土壤有效态Cd含量、水稻根系和秸秆Cd含量及其累积量；淹水条件下,水稻所受到的氧化胁迫最低,水稻的生长最好,干物质累积最多；分析不同水分管理方式下水稻地上部、根、根胶膜中Cd含量,根胶膜Fe含量,土壤盐酸提取态硫含量、盐酸提取态Cd及Fe含量之间的相关关系,发现连续淹水处理极显著地降低了水稻对Cd的吸收,这可能是由于淹水条件下土壤盐酸提取态Cd极显著降低、盐酸提取态Fe则显著上升导致的Fe、Cd竞争造成的,而淹水条件下CdS沉淀的形成在很大程度上影响了土壤Cd的有效性。3.田间试验条件下水分管理方式对水稻镉吸收与分配的影响研究以两个籽粒Cd含量具有明显差异的水稻品种为供试材料,研究了全生育期淹水(W)、间歇灌溉(I)、当地生产灌溉方式(CK)及不灌水旱作(D)等四种不同水分管理方式下,水稻的Cd吸收特点,并结合土壤提取态Cd及生理指标变化,探讨了不同水分管理方式对水稻Cd积累的影响及机理。结果表明,与当地生产灌溉方式相比,全生育期淹水降低了土壤盐酸提取态Cd、根胶膜Cd含量及糙米、谷壳、秸秆中Cd含量,而间歇灌溉及不灌水旱作处理均提高了以上几项指标的数值;与CK相比,品种A16实际产量为：W、I、D处理分别增产74.9%(p<0.05)、61.9%(p<0.05)、49.0%(p>0.05)；品种A159实际产量则为：D处理增产9.18%(p<0.05),W、1分别减产7.76%(p>0.05)、1.05%(p>0.05)；D处理均增加了两个水稻品种经济产量,因为D处理下均极显著地提高了千粒重；四种水分处理下,品种A159的糙米Cd含量均高于品种A16,CK、W、I、D处理下A159品种水稻糙米中Cd含量分别比A16高1.14(p<0.01)、1.56(p<0.01)、0.602(p<0.01)、0.389(p>0.05)倍。更多还原

【Abstract】 Rice (Oryza sativa) is globally one of the most important food crops. In recent years, contamination of arable soils by cadmium (Cd) is more serious with the rapid development of industry and agriculture, which affects rice grain yield and its edible risk. Rice shows considerable genotypic variation in Cd accumulation in grains. A promising for reducing the Cd concentration in rice grains is breeding or engineering low-Cd accumulating cultivars. This requires a prior understanding of the Cd accumulation mechanisms in rice plants. Agronomic regulation is the effective approach for reducing grain Cd concentration in Cd contaminated soil. Research has shown that flooding reduced cadmium concentrations in rice grains, whereas aerobic treatment increased the concentration of cadmium. A hydroponic culture and a pot experiment were conducted, using two rice varieties with different grain Cd accumulation characters, to investigate the rice Cd uptake and translocation and the plant physiological mechanisms. Another pot experiment and a field experiment were conducted to investigate influence of different water management methods on Cd uptake and translocation by rice and the mechanisms. The main results were showed as follows.1. Uptake and translocation of Cd by two rice cultivars with different grain accumulation characters and the relevant physiological effectsA hydroponic culture and a pot experiment were conducted, using two rice cultivars with different grain Cd accumulation characters, to investigate Cd uptake and translocation in rice and their physiological effects in several growth stages. In the pot experiment, the grain Cd concentrations of A16 and A54 were 0.31 mg kg-1 and 0.88 mg kg-1, respectively, when soil total Cd concentration was 1.57 mg kg-1. Both hydroponics culture and pot experiment showed that A16 absorbed and translocated more Cd than A54 during the seedling stage. However, after the seedling stage, the amounts of Cd uptake and translocation by A54 were higher than A16. Root Cd sequestration and rhizosphere soil properties may explain the differences by rice Cd absorption and translocation between the seedling stage and other stages. From the comparison of Cd accumulation in rice of two cultivars at various growth stages, it was observed that the increase from the seedling stage to jointing stage was the highest. Therefore, this may be the key period for Cd uptake and accumulation for both cultivars. By analyzing the shoot and root Cd concentrations, Cd translocation rate from roots to shoots and non-protein thiol (NPT) that can sequestrate Cd within the root in different growth stages, we found that the difference in grain Cd concentrations of A16 and A54 could be attributed to root uptake and translocation to shoot of rice.2. Influence of different water management methods on Cd uptake and translocation by rice and the mechanisms in a pot experimentA pot experiment was conducted to investigate effect of irrigation models of flood, intermit and aerobic irrigation on rice Cd uptake and translocation and the mechanisms. Results showed that flooding significantly reduced soil HCl extractable Cd, and roots and shoots Cd in rice. This could be interpreted as the decrease of soil HCl extractable Cd and the Fe2+ competition in adsorption by iron plaque of rice root and absorption by rice root. In addition, the formation of precipitatable CdS under flooding condition influenced the soil available Cd, to a great extent.3. Influence of different water management methods on Cd uptake and translocation by rice in a field experimentA field experiment was conducted, using two rice cultivars with different grain Cd concentrations, to investigate the influence of waterflooding during the whole growth stages (W), local production irrigation method (CK), intermit irrigation (I) and no irrigation drought (D) on Cd uptake and translocation in rice and the mechanisms. Results showed that compared with CK, "W" reduced soil HCl extractable Cd, and Cd concentrations in the root, shoot, husk and brown rice, whereas, "I" and "D" enhanced the above indexes.Compared with CK, treatments of "W", "I" and "D" increased grain yields of A16 74.9% (p< 0.05),61.9%(p<0.05) and 49.0% respectively; As for A159, "D" treatment increased 9.18% (p<0.05), while, "W" and "I" decreased 7.76% (p>0.05) and 1.05% (p>0.05), respectively. The increase of grain yields of both the tesed rice varieties under "D" treatment could be explained as D treatments enhanced the 1000-grain weight.Compared with A16, the brown rice Cd concentration of A159 increasd 1.14 (p<0.01), 1.56 (p<0.01),0.602 (p<0.01) and 0.389 (p>0.05) respectively under CK, W, I and D treatments.更多还原