中文摘要：

采用水培体系,对幼苗期油菜根系进行不同浓度（1,5,10,25,50 mg/L）的Cd2＋胁迫,胁迫1,3,6,9 d后测定其若干相关生理特性指标,研究镉对油菜根系生理特性的影响。研究结果表明：Cd2＋胁迫下油菜根系的电解质相对外渗率、MDA和游离脯氨酸的含量都随着Cd2＋处理浓度的增加而增大,并且各处理浓度与对照差异性显著（P〈0.05）;可溶性蛋白、可溶性糖含量随着Cd2＋处理浓度的增加先升高后降低,低浓度（小于5 mg/L）有明显的促进作用;且各指标随着处理时间的延长逐渐上升。SOD酶活性在胁迫3 d后,随处浓度和处理时间的延长先升高后降低,APX、CAT和POD酶活性随着Cd2＋胁迫浓度的升高,先升高后降低,但各种抗氧化酶对浓度的敏感性不同,SOD〉APX〉CAT〉POD。综上述,镉胁迫对油菜根系生长有一定的伤害,使得根系细胞膜透性增加,膜脂过氧化加重,根系利用自身渗透调节物质和抗氧化酶活性升高来调节并适应环境,但是高浓度的镉环境使得根系细胞中积累较多的活性氧等自由基而严重伤害细胞,可溶性蛋白含量以及抗氧化酶活性下降,影响根系生长。

英文摘要：

In this study, water culture method was used to study the effects of different Cd2＋ contentrations（ 1, 5, 10, 25, and 50 mg/L） on the roots of Brassica napus L. After 1,3, 6, and 9 d under the Cd2＋ exposure, the physiological characteristics were measured. The results showed that, The relative electrolyte leakage rate, the malonaldehyde （MDA） and free proline content of the roots of Brassica napus L increased with the increasing contentrations of Cd2＋ , and there were significant （ P 〈 0.05 ） differences among the different treatments; the soluble protein content and soluble sugar content both ascended firstly then declined with the increasing contentrations of Cd2＋ , lower concentrations （ 〈 5 mg/L） of Cd2＋ had obviously stimulation affection; and the physiological indexes gradually ascended with time under the Cd2＋ stress. The results also showed that, various antioxidant enzymes＇ activity also ascended firstly then declined with Cd2＋ contentrations increasing, and they were sensitive to the Cd2＋ stress as the following sequences ： SOD 〉 APX 〉 CAT 〉 POD. So it can be concluded that, cadmium stress is harmful to the growth of roots of Brassica napus L. , which increased the membrane permeability and membrane lipid peroxidation of cell. The permeability substances and the rise of antioxidant enzymes＇ activity are helpful to adaption to environment, but higher content of cadmium environment significantly destroys the cell of the roots, soluble proteins and antioxidant enzymes＇ activity decline, finally, which greatly inhibits the growth of plant roots.