镉胁迫下水稻SOD活性和MDA含量的变化及其基因型差异

以4个水稻品种为材料，采用土培试验，研究了不同土壤镉浓度对水稻超氧化物歧化酶（SOD）活性和丙二醛（MDA）含量的影响，水稻叶片SOD活性和MDA含量在生育进程中的变化，以及SOD活性和植株镉含量的关系。结果表明： 1）轻度镉胁迫有利于提高水稻的SOD活性，而高浓度镉胁迫对水稻的SOD活性有抑制作用；MDA含量与SOD活性存在负相关关系，随着土壤镉浓度的增加，MDA含量先下降后上升。2）在水稻生育过程中，SOD活性分蘖期>乳熟期>齐穗期；MDA含量随生育期一直增加。3）镉胁迫对水稻叶片SOD活性的影响存在基因型差异，分蘖期不同水稻基因型间SOD活性的差异最大。4）水稻的SOD活性与植株和稻米的镉含量呈负相关，齐穗期的SOD活性与镉含量的相关性达显著水平。

Changes of SOD Activity and MDA Content in Rice Exposed to Cd Stress as Affected by Genotype

A pot experiment was conducted to investigate the effects of soil cadmium (Cd) stress on superoxide dismutase (SOD) activity and malindialdehyde (MDA) content in rice plant, the correlations between SOD activity, MDA content and Cd content in plant by using four rice cultivars. SOD activity increased when plants were subjected to slight Cd stress, but was inhibited when subjected to high soil Cd concentration. There was a negative correlation between SOD activity and MDA content, and MDA content declined at low Cd level and increased at high Cd level. SOD activity varied with growth stage in the order of tillering stage> milky stage>full heading stage, while MDA content showed the constant increase in the whole growth period. There was a significant difference among the four rice cultivars in the changes of SOD activity caused by Cd stress, with the largest difference at the tillering stage. A negative correlation between SOD activity and Cd content of rice plant and brown rice was found, and the correlation was significant at the full heading stage.