供钾水平对空心莲子草富集3种重金属能力的影响

Effect of Potassium Supply Level on Three Heavy-metal Accumulation in Alternanthera philoxeroides

关键词:  空心莲子草  富钾水平  重金属富集  植物修复

Key words:  Alternanthera philoxeroides  potassium enriching level  heavy metal accumulation  phytoremediation

摘要:

以空心莲子草(Alternanthera philoxeroides)作为研究材料,通过模拟富营养化水体实验,研究空心莲子草在消减重金属污染方面的能力;同时通过供应足量钾离子,进一步揭示空心莲子草植株钾离子水平与重金属富集能力及抗逆之间的关系。研究结果表明,空心莲子草对重金属元素Mn²⁺、Pb²⁺及Cd²⁺有较好的富集能力,主要在地上部积累;空心莲子草对这3种重金属元素的敏感程度为Cd ²⁺ > Pb²⁺ > Mn²⁺;在低浓度(1mM)K⁺供应下,高浓度(500 μM)的Mn²⁺、Pb²⁺及Cd²⁺处理明显抑制空心莲子草的生长(Mn²⁺、Pb²⁺抑制作用主要发生在根系,Cr³⁺抑制植物整株),与对照相比,生物干重分别降低8.7%、22.6%与74%,提高K⁺浓度(10mM)可显著缓解这3种重金属对植株生长的抑制,生物干重分别有效提高22.2%、39.3%与90.7%;此外,提高K⁺浓度(10mM)可显著提升植株对这3种重金属的耐受力和富集能力,整株水平上富集量分别提高23%、19%及30%。

Abstract:

(Alternanthera philoxeroides) is well known for its potassium (K⁺)-enriching capabilities and its strong resistance to undesired growth conditions.The close correlations between K⁺-enriching level and heavy metal accumulation was evaluated via nutrient solution culture examinations. The results revealed that A.philoxeroides possessed the capacity to enrich 3-metal cations of Mn²⁺, Pb²⁺ and Cd²⁺, which were mainly accumulated in the shoots.The sensitivity of A.philoxeroides to these 3 heavy metals was followed as Cd²⁺ > Pb²⁺ > Mn²⁺.Based on 1 mM K⁺ conditions, 500 μM heavy-metal treatment significantly inhibited the growth of A.philoxeroides plants (the suppression induced by Mn²⁺, or Pb²⁺ mainly occurred in roots, and Cd²⁺ in the whole plant level).Compared to the control conditions, 500 μM Mn²⁺, Pb²⁺ and Cd²⁺ treatment caused decrease in dry weight of 8.7%, 22.6% and 74%, respectively.However, high external K⁺ (10 mM) well alleviated the depressed symptoms, which resulted in the increase in dry weight of 22.2%, 39.3% and 90.7%, respectively, associated with the increment in these 3 heavy-metal content of 23%, 19% and 30%.