铅污染土壤中根表铁膜对宽叶香蒲利用磷的影响

Effect of iron plaque on utilization of phosphorus by broad-leaf cattail(Typha latifolia L.) in a lead-contaminated soil

为研究铅污染土壤中根表铁膜对宽叶香蒲（Typha latifoliaL.）磷利用效率的影响,利用根袋培养方法在两个Fe^2＋水平（201、00 mg/L）下诱导根表形成铁膜的宽叶香蒲移栽于土壤中,经4个Pb^2＋浓度（0、100、5001、000 mg/kg）处理后淹水培养4周,分析根表铁膜和植物体内磷含量。结果表明,地上部生物量随着铅污染强度的增加呈降低趋势,但差异不显著（P〉0.05）;低铁（20 mg/L）诱导处理的地上部和地下部生物量分别比相应高铁（100 mg/L）诱导的高3.5%1-9.6%和7.6%3-9.8%,且铁对地上部生物量的影响达到极显著差异（P〈0.01）。根表铁膜量随铅污染程度的增加而下降;高铁诱导处理宽叶香蒲的新根形成的铁膜量以及其吸附的磷均高于低铁诱导处理的植株。除1000 mg/kg铅处理外,低铁诱导后植株中磷的含量均比高铁诱导的植株高。本试验条件下,铅污染土壤中植物对磷的利用表现为低铁膜量大于高铁膜量。

To investigate the effect of iron plaque on phosphorus （P） utilization by broad-leaf cattail （ Typha latifolia L. ） in a lead （Pb） contaminated soil, we transplanted the broad-leaf cattail seedlings with iron plaque induced at two levels of Fe^2＋ （20, 100 mg/L） in rhizobags into soils previously treated with four levels of Pb （0, 100, 500, 1000 mg/kg）. After the plants grew four weeks under the waterlogged condition, the amounts of iron plaque on roots and P in plants were measured. The results showed that the over-ground and underground biomass of cattail treated with low ferrous （20 rag/L） was 3.5% - 19.6% and 7.6% - 39.8% higher than that with high ferrous （ 100 mg/L）, respectively, and decreased with the doses of lead （ P 〉 0.05）, and iron had significantly influence on the over-ground biomass （ P 〈 0.01 ）. The amounts of iron plaque on new roots were decreased with the increase of lead dose. Phosphorus adsorbed in iron plaque on new roots treated with low ferrous was generally lower than that treated with high ferrous. The concentrations of phosphorus in over-ground and underground part of plants treated by low ferrous was higher than that with high ferrous, except for the Pb 1000 mg/kg treatment. It is concluded that lower amount of iron plaque on roots appeared to be more beneficial for phosphorus utilization by broad-leaf cattail under the condition of this experiment.