Abstract: The growth, lipid peroxidation and antioxidant enzyme system of two rice cultivars (Bing 97252, low grain Cd accumulation, and Xiushui 63, high grain Cd accumulation) were studied with a hydroponic experiment under four Cd levels (0.0, 0.1, 1.0 and 5.0 μmol/L). Cd stress reduced plant height and chlorophyll content in rice leaf, altered malondialdehyde (MDA) content and activities of superoxide dismutase (SOD), catalase(CAT) and peroxidase (POD) in rice leaf. Roots and shoots of rice plants responded differently to Cd stress in terms of antioxidant enzyme activity. Generally, the activities of SOD, POD and CAT in shoots and roots dropped with increase of Cd level, while MDA content increased with Cd level, which would be more pronounced in Xiushui 63 than Bing 97252. At booting stage a decrease of 46-52% in SOD activity was noted in the roots of plants exposed to 5.0 μmol/L Cd, while at tillering stage the decrease was 13-19% compared to the control. A significant decrease in chlorophyll content in rice leaf and plant height was noted in higher Cd treatment (1.0 and 5.0 μmol/L). The higher MDA and less chlorophyll content were found in Xiushui 63, indicating that Xiushui 63 was more sensitive to Cd stress than Bing 97252.

Key words: rice, cadmium, anti-oxidative enzyme, genotype, plant growth

摘要： 以籽粒镉积累水平不同的两种品种（丙97252，低积累型；秀水63，高积累型）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，镉处理设0.0、0.1、1.0和5.0 μmol/L 4个水平。结果表明，镉胁迫抑制植株生长和叶绿素合成，改变植株丙二醛（MDA）含量和超氧物歧化酶（SOD）、过氧化氢酶（CAT）、过氧化物酶（POD）活性。在抗氧化酶活性上，根和地上部对镉胁迫的反应存在着差异。总体上，SOD、CAT和POD活性随镉水平的提高而减少，而MDA含量则表现相反。根和地上部MDA含量随着培养液中镉浓度提高而增加，且增加幅度秀水63明显大于丙97252。与对照相比，生长在5.0 μmol/L Cd处理下的植株， SOD活性在孕穗期下降46%~52%，在分蘖期仅下降13%~19%。高浓度镉胁迫下，两品种在MDA含量的增加幅度和叶绿素含量的降低幅度上表现不同，显示出它们对镉的耐性存在着差异。

关键词: 水稻, 镉, 抗氧化酶, 基因型, 植株生长