Effect of direct-current electric field on the growth ofsubmerged macrophyte <i>Vallisneria natans</i>

Abstract

沉水植物对维持湖泊生态系统平衡有重要作用，广泛应用在水体和沉积物污染修复领域.利用电场强化沉水植物修复过程是一种新的植物修复强化方法.本文研究了不同电压强度作用下沉水植物苦草的生长和生理响应，以期为应用电场强化沉水植物修复过程提供依据.结果表明：0.2～1.0 V电压可以促进苦草生长，而1.5～3.0 V电压则会抑制其生长.其中，0.5 V电压对苦草生长的促进效果最明显，生物量、平均株高、平均叶长、根尖数、新芽数和总叶绿素含量都比对照组显著增加；而3.0 V电压处理组的苦草在实验结束时出现萎蔫和凋亡，与对照组相比，叶绿素含量显著降低，丙二醛含量则极显著增加，表明苦草生长受到严重胁迫.系统上覆水的温度在不同处理组之间没有显著变化，上覆水的pH值在电压为1.0、1.5和3.0 V时显著下降，最终接近中性，上覆水的溶解氧浓度只在3.0 V电压处理组时表现显著下降；沉积物表层5 cm处的氧化还原电位随着电压增大显著下降，最终对苦草的生长形成胁迫.因此，本实验的结论是：0.2～1.0 V电压有助于沉水植物苦草的生长和强化植物修复过程，而1.5～3.0 V电压会破坏苦草组织，同时导致苦草生境变差，不利于沉水植物苦草的生长.;Submerged macrophytes play an important role in maintaining the ecosystem balance of lakes and are used widely in the remediation of contaminated water and sediment. Electric field provides a new technological approach to enhance the restoration of submerged plants. In this study, the growth performance and physiological response of Vallisneria natans under different voltage intensities were investigated. The results show that the voltage ranging from 0.2 to 1.0 V can stimulate the growth of Vallisnera natans, while the voltage ranging from 1.5 to 3.0 V can inhibit the growth. The obvious stimulation was observed under the voltage of 0.5 V. Compared with the control experiment, the obvious increase in the aspects of biomass, average stem length, average leaf length, the number of root tips, the number of buds and the content of total chlorophyll were observed. The plants grew worst under the voltage of 3.0 V, and some of them ended up wilting even death. The content of total chlorophyll in their leaves strikingly decreased but the content of MDA markedly increased, which showed the plants suffered serious stress. The temperature of overlying water did not change obviously among different voltages. The pH of overlying water dropped remarkably under the voltage of 1.0, 1.5 and 3.0 V, close to neutral. The content of dissolved oxygen decreased markedly under the voltage of 3.0 V. The redox potential of 5 cm under the sediment surface decreased sharply when the voltage was raised, and finally inhibited the growth of Vallisnera natans. Thus, these findings show that the voltage ranging from 0.2 to 1.0 V will contribute to the growth of Vallisnera natans and enhance the restoration of plants, while the voltage ranging from 1.5 to 3.0 V will damage the tissues of Vallisnera natans, resulting in worsening the living condition and inhabiting the growth of Vallisnera natans.