| 摘要: |
| 采用营养液培养法,比较了东南景天(Sedum alfredii Hance)在不同的Cd,Pb供应水平下的生长反应,以及对Cd,Pb吸收与积累特性的差异。结果表明,东南景天不仅在生长速度上对不同浓度的Cd,Pb处理反应差异显著,而且在Cd,Pb吸收与转运特性上也有明显差异。东南景天对Cd,Pb耐受的临界浓度分别为500和1 000 μmol/L,在此浓度以下,Cd,Pb对水培条件下的东南景天的生长基本无抑制作用。东南景天地上部的Cd,Pb含量均随着Cd,Pb供应水平的提高而增加。在500 μmol/L的Cd水平下,叶和茎中的Cd含量均达到峰值,分别为5.677和5.274 g/kg;叶和茎中的最大含Pb量出现在供Pb 200和1 500 μmol/L的水平下,分别为0.169和1.167 g/kg。根中的Cd,Pb含量均在最高的Cd,Pb供应水平下(2 500 μmol/L)达到最大值,分别为17.820和9.437 g/kg。在设定的Cd,Pb供应水平条件下,植株各部位的Cd含量均大于Pb含量。植株不同部位Cd的含量表现为叶>茎>根,而Pb含量表现为根>茎>叶。Cd在东南景天地上部的积累量远大于Pb,且Cd在地上部与根系中积累量的比值均大于1,而Pb则小于1。上述结果说明,东南景天对Pb的耐受性大于Cd,但对Cd的吸收和向地上部的转运能力远大于Pb。从水培条件下东南景天地上部的Cd含量来看,东南景天是一种Cd超积累植物。 |
| 关键词: 东南景天 镉 铅 生长反应 积累特性 超积累植物 |
| DOI： |
| 分类号: |
| 基金项目:国家自然科学基金项目(20277035)；科技部973项目(2002CB410804) |
|
| Comparing the characteristics of growth response and accumulation of cadmium and lead by Sedum alfredii Hance |
|
|
| Abstract: |
| Characteristics of plant growth and uptake and accumulation of cadmium (Cd) and lead (Pb) by Sedum alfredii Hance in response to Cd and Pb concentration were compared by hydroponic experiments and significant differences were found between the two heavy metals.Results showed that growth of root dry matter weight of the plants was slightly affected by Cd up to 500 μmol/L,whereas growth of shoot dry matter weight increased slightly and peaked at 100 μmol/L Cd.In contrast,growth of shoot dry matter weight was slightly affected by Pb till 1 000 μmol/L,but growth of root dry matter weight enhanced significantly by Pb supply and peaked at 1 000 μmol/L Pb.The thresholds for the plant growth response to external Cd and Pb were 500 and 1 000 μmol/L respectively.Cd contents in different parts were higher than Pb,especially in leaves.At Cd≤500 μmol/L,plant Cd contents among various parts,the order was recorded as leaf>stem>root,whereas an adverse order of plant Pb contents,i.e.root>stem>leaf was observed at Pb≥200 μmol/L.Shoot Cd contents increased with external Cd supply,and reached maximum at 500 μmol/L Cd,being 5.677 and 5.274 g/kg in leaves and stems,respectively.Similarly,shoot Pb contents increased by external Pb,which maximum Pb content in leaves appeared at 200 μmol/L Pb,being 0.169 g/kg;whilst maximum Pb content in stems reached at 1 500 μmol/L Pb,being 1.167 g/kg.Root maximum contents of Cd and Pb both were at 2 500 μmol/L Cd (Pb),being 17.820 g/kg (Cd) and 9.437 g/kg (Pb),respectively.In addition,at 500 μmol/L Cd the plant obtained its maximum shoot Cd accumulation of 3.29 mg/plant,whilst the ratio of shoot/root Cd accumulation reached 16.18.On the contrary,maximum shoot Pb accumulation was 0.32 mg/plant at 1 000 μmol/L Pb and the ratio of shoot/root Pb accumulation was 0.30.It is suggested that Sedum alfredii has higher tolerance to Pb than to Cd,whereas its abilities to uptake and transport Cd were greatly higher than to Pb,and is a Cd hyperaccumulator in terms of its shoot Cd contents. |
| Key words: Sedum alfredii Hance cadmium lead growth response accumulating characteristics hyperaccumulator |
