Cd胁迫下杂交水稻对Cd的吸收及其动态变化

镉（Cd）是非必需的有毒元素，是农业环境和农产品的重要污染物，易被水稻吸收并在籽粒中积累。不同水稻品种拥有不同的独特基因，导致水稻籽粒吸收积累Cd的能力存在一定的差异。因此，开展不同水稻品种耐Cd特性及其不同生育期的吸收转运效率研究具有重要意义。本文采用水培试验，研究了两个水稻（Oryza sativa L.）品种：D83A/R527（低吸收累积Cd）和辐优838（高吸收累积Cd）在不同质量浓度Cd胁迫下籽粒Cd质量分数及不同生育时期水稻根、茎、叶内Cd的吸收积累量及其动态变化特点。结果表明，两种水稻品种在Cd胁迫下籽粒Cd积累量差异显著，辐优838在1.0 mg·L^-1 Cd质量浓度胁迫下籽粒Cd质量分数就已超过国家食品卫生标准；在1.0~3.0 mg·L^-1 Cd质量浓度胁迫下，D83A/R527籽粒内Cd质量分数仅为辐优838的50~60%。随着Cd处理浓度增加和生育时期推进，两种水稻各部位Cd吸收量均表现为逐渐增加，其增加幅度总体表现为：辐优838〉D83A/R527；不同部位中，根的积累效应最强，叶片吸收积累能力最低，辐优838茎、叶吸收积累效率分别是D83A/R527的1.5~2.0倍左右。在1.0~3.0mg·L^-1 Cd胁迫下，水稻Cd积累差异较为显著的时期为灌浆期，辐优838的根系向茎、叶的转移效率大于D83A/R527，且D83A/R527主要表现为由根系向茎Cd转移效率较高，叶片Cd积累相对较少。灌浆期是水稻籽粒干物质积累的重要时期，也是吸收累积Cd的重要时期，这为筛选低吸收积累水稻品种和调控Cd在水稻籽粒中的吸收累积奠定了重要理论基础。

Absorption of Cd by hybrid rice under the Cd stress and its dynamic change

Cadmium （Cd） is non-essential but toxic element. It is an important agricultural pollutant in environment and farm product. It is easily absorbed and accumulated in rice grain, different rice varieties have different unique genes, resulting in the ability of Cd uptake and accumulation in rice grain differently. So, Cd-resistant characteristics of rice varieties and their transport efficiency in different growth stages are important for Cd-pollution control. Cd content in grain, Cd accumulation and its dynamic changes in different stages of rice root, stem and leaves under the Cd stress had been studied in two type of rice （D83A/R527 and Fuyou 838） by hydroponic experiments. The result showed that, the Cd content of two type of rice under Cd stress was highly significant. In 1.0 mg·L^-1 Cd stress, the grain Cd concentration of Fuyou 838 had exceeded the national food safety standards. At 1.0~3.0 mg·L^-1 Cd treatments, the grain Cd concentration of D83A/R527 was only 50~60%of Fuyou 838. With the increase of Cd treatment and the growing progress, Cd content in different parts of rice showed gradual increasing, Fuyou 838 was greater than D83A/R527. Considering about the different parts, the accumulation capacity of root was the highest, while that of leaves was the lowest, and accumulation in Fuyou 838 was higher than that of D83A/R527. The uptake of Cd in stems, leaves and accumulation efficiency of Fuyou 838 was about 1.5~2.0 times than that of D83A/R527. For about different growth stages, the absorption capacity of Cd in filling stage was the highest efficiency under the 1.0~3.0 mg·L^-1 Cd stress, and its Cd content was largest in different parts of rice. The Fuyoou 838 had the higher Cd transfer efficiency from root to stem and leaf. The D83A/R527 had the higher Cd transfer efficiency from root to stem, but had the lower Cd transfer efficiency from stem to leaves, and the Cd accumulation in leaves was lowest. In a word, the filling stage was not only the important period during the dry matter accumulation for rice, but also was the critical period of Cd accumulation. These characteristics established the major theoretical foundation for the selecting of low Cd uptake or accumulation and controlling of Cd pollution in rice varieties.