镉胁迫对玉米幼苗抗氧化系统及光合作用的影响

采用水培方法，在玉米幼苗进入三叶期后向培养液中加入不同浓度氯化镉（0、10^-6、10^-5、10^-4 mol·L^-1），胁迫不同时间（5、10、15 d）后对幼苗进行各项指标检测。结果表明，低浓度（10^-6 mol·L^-1）及中浓度（10^-5 mol·L^-1）镉胁迫对幼苗生长均有较强刺激作用，而中浓度胁迫对地上部分作用更明显；低浓度镉胁迫对根部及叶片抗氧化酶（SOD、POD、CAT及ASA－POD）活性影响较小，只是根部POD、ASA－POD活性明显升高，而中浓度胁迫对除SOD外其他抗氧化酶活性均有显著促进作用；MDA含量均未有显著升高，可见根部及叶片未受到氧化损伤；两种浓度胁迫下，Fv′/Fm′虽下降，净光合速率有所升高。高浓度镉（10-4 mol·L^-1）胁迫下幼苗生长几乎停止；根部SOD及CAT活性升高，而POD和ASA－POD被明显抑制，叶片中CAT、POD及ASA－POD活性显著升高；根部受到显著氧化损伤；各项光合参数（Fv/Fm、Fv′/Fm′和净光合速率）均显著降低。

The Influence of Cadmium（ Cd^2＋） to the Antioxidant System and Photosynthesis of Seedling of Zea mays L.

The influence of Cd^2＋ to the antioxidant system and photosynthesis of maize（ Zea mays L. ） was studied systematically. Seedlings were cultivated in Hoagland liquid medium, and in the three-leave-period were treated with different concentrations of CdC12 （0, 10^-6, 10^-5, 10^-4 mol· L^-1 ）. After 5,10 and 15 days of stress, physiological parameters of seedlings were measured. In the stress of low（ 10^-6 mol· L^-1 ） and middle（ 10^-5 mol·L^-1 ） concentration, the growth of seedlings was promoted obviously whereas that of parts above the earth more notably in the stress of 10^-5 mol·L^-1; In the stress of 10^-6 mol·L^-1, the activities of POD and ASA-POD in root increased and activities of other anti-oxidant enzymes changed little; However, the stress of middle concentration made activities of anti-oxidant enzymes increase obviously except SOD; The content of MDA was not high compared with control, which showed that seedlings were not hurt by oxidation; Fv′/Fm′ decreased and the net photosynthetic rate rose. In the concentration of 10^-4 mol· L^-1, the seedlings almost did not grow; The activities of SOD and CAT in root increased and those of POD and ASA-POD were inhibited seriously, and the activities of CAT, POD and ASA-POD in leave increased sharply; Root was hurt oxidately; Photosynthetic parameters（Fv/Fm, Fv ′/Fm′ and net photosynthetic rate ） decreased notably.