锌、镉及其复合胁迫下白花泡桐幼苗的生理及富集特征

Physiological and enrichment characteristics of Paulownia fortunei seedlings under zinc, cadmium and their combined stress

摘要:

采用水培培养的试验方法，研究白花泡桐幼苗在锌 (Zn)、镉 (Cd) 单一及复合胁迫下的生理生化响应及对重金属的富集、转移特征变化。结果表明，单一及复合重金属胁迫下，白花泡桐的生物量、株高及过氧化物酶 (Peroxidase，POD) 活性均随处理浓度的增加而降低。在复合污染下，Zn、Cd在植株的株高及生物量上表现出拮抗作用。与对照比，单一胁迫下，随着Zn浓度的增加，白花泡桐叶绿素含量和过氧化氢酶 (Catalase，CAT) 活性先增加后减小，超氧化物歧化酶 (Superoxide dismutase，SOD) 活性升高，地上部丙二醛 (Malondialdehyde，MDA) 含量先减小后增加；随着Cd浓度的增加，叶绿素含量和过氧化氢酶 (CAT) 活性升高，超氧化物歧化酶 (SOD) 活性及地上部丙二醛 (MDA) 含量先增加后减小，复合胁迫下，则表现出更加复杂的生理响应。白花泡桐幼苗对Cd的富集部位集中在根部；对Zn的富集部位集中在地上部，且转移系数大于1.00；Zn的加入会促进重金属向地上部分的转移；白花泡桐具有对复合重金属污染地进行有效的生态恢复的潜力。

Abstract:

The hydroponic culture test method was used to study the physiological and biochemical responses of Paulownia fortunei seedlings under Zn stress, Cd stress, and combined Zn and Cd stress as well as changes in the enrichment and transfer characteristics of heavy metals. Under single and combined heavy metal stress, the biomass, plant height, and peroxidase (POD) activity of P. fortunei decreased as the treatment concentration increased. Combined Zn and Cd affected adversely plant height and biomass. As the concentration of Zn increased when applied alone, the chlorophyll content and catalase (CAT) activity of P. fortunei first increased and then decreased, the superoxide dismutase (SOD) activity increased, and the aboveground malondialdehyde (MDA) content first decreased and then increased. As the concentration of Cd increased when applied alone, chlorophyll content and CAT activity increased, and SOD activity and aboveground MDA content first increased and then decreased. Under both Cd and Zn, the physiological response was more complex. Cd in the seedlings of P. fortunei was concentrated in the root. In contrast, Zn was concentrated in the upper part of the ground, and its transfer coefficient was greater than 1.00. Thus, the addition of Zn promotes the transfer of heavy metals to the above-ground portions of plants. Generally, P. fortunei can effectively promote ecological restoration under complex forms of heavy metal pollution.