美人蕉对镉的胁迫反应及积累特性

美人蕉(Canna indica)是我国城区普遍栽植兼具绿化、观赏和净化环境等重要价值的地被植物。为研究美人蕉对Cd的胁迫反应及积累特性, 使用盆栽方法对美人蕉进行不同含量水平Cd处理, 测定其生长过程中部分形态、生态、生理指标的变化和收获后体内Cd含量。结果表明, Cd含量小于1 mg·kg^-1时对美人蕉生长影响不大, 大于5 mg·kg^-1时抑制美人蕉生长。Cd含量小于5 mg·kg^-1时延长了美人蕉的花期。随着Cd含量的增大, 美人蕉根系活力、叶绿素含量和含水量逐渐降低, 可溶性糖含量先升高后降低, 游离脯氨酸含量和细胞膜透性逐渐升高。Cd在美人蕉体内的分布为根系>地上部分, 随着Cd含量的增大, 美人蕉根系和地上部分Cd含量逐渐升高、富集系数和转运系数逐渐降低; Cd含量为20 mg·kg^-1时美人蕉对Cd的积累量最大, 为5.89 mg·株^-1。综合分析美人蕉的生长、生理生态变化及富集Cd的能力, 美人蕉适于土壤Cd含量小于1 mg·kg^-1条件下的园林应用。

Stress responses of Canna indica to Cd and its accumulation of Cd

Aims The valuable ornamental plant Canna indica is widely distributed in city gardens and on roadsides in China. Our objective was to study the stress responses of C. indica to cadmium (Cd) and its accumulation of Cd. Methods With pot culture experiments, C. indica was cultured with different Cd concentrations. Morphological, ecological, physiological indexes were observed during the growth of C. indica. The distribution of Cd in C. indica plants was determined after harvest. Important findings The Cd treatment of <1 mg·kg–1 had no obvious effect on growth of C. indica; however, Cd concentration of >5 mg·kg–1 inhibited growth. The flowering period was prolonged with <5 mg·kg–1 Cd concentration. With increasing Cd concentration, root activity, chlorophyll and water content all decreased, soluble sugar content initially increased and then decreased, and free proline content and permeability of cell membrane increased gradually. The distribution of Cd in C. indica was root > shoot. With increasing Cd concentration of the medium, Cd concentration in shoots and roots increased; however, the accumulator and translocation factors decreased gradually. The maximum accumulation of Cd in C. indica was 5.89 mg·plant–1 with the treatment of 20 mg·kg–1 . It is concluded that C. indica is suitable for landscaping use when the Cd concentration in soil is <1 mg·kg–1 .