种植密度对镉锌污染土壤伴矿景天植物修复效率的影响

田间微区试验研究了不同种植密度对伴矿景天生长和地上部重金属吸收量的影响.结果表明,适度增大种植密度可促进伴矿景天的生长,显著提高其地上部生物量,但过分密植对植物地上部增产无显著贡献.种植密度由11万株/hm2上升到44万株/hm2时,伴矿景天地上部Cd、Zn吸取量显著上升,分别由0.208 kg.hm-2上升至0.631 kg.hm-2、13.2 kg.hm-2上升至58.7kg.hm-2;但种植密度从44万株/hm2增大到100万株/hm2时,植物地上部重金属吸取量并无显著提高.伴矿景天种植密度为44万株/hm2时,在Cd、Zn分别为(3.04±0.11)mg.kg-1和(1 299±96)mg.kg-1的污染土壤上种植1 a,对镉锌的修复效率分别达21.1%和4.60%,表明选择适宜的密度种植伴矿景天有利于增大植物地上部Cd、Zn吸取量,从而缩短修复时限.

Effect of Planting Densities on Yields and Zinc and Cadmium Uptake by Sedum plumbizincicola

A field plot experiment was conducted to study the effects of planting densities on the growth and heavy metals uptake by Sedum plumbizincicola . The results showed that yields of Sedum plumbizincicola were enhanced with the increase of planting density; however, there was no further increase when planting density was too high. With planting density increasing from 1.1 × 10~5 plants per hm~2 to 4.4 × 10~5 plants per hm~2 , Cd and Zn uptake of aboveground Sedum plumbizincicola increased from 0.208 kg·hm~(-2) to 0.631 kg·hm~(-2) , from 13.2 kg·hm~ to 58.7 kg·hm~(-2) , respectively; yet, there was no significant enhancement between the planting density of 4.4 × 10~5 plants per hm~2 and 1.0 × 10 plants per hm~2. When planting density was 4.4 × 10~5 plants per hm~2 , the Cd and Zn removal rates in contaminated soil were 21.1% , 4.60%, respectively. Appropriate planting density would benefit Cd and Zn uptake of aboveground Sedum plumbizincicola, and shorten phytoremediation period.