Pb胁迫对欧美杂交杨（Populus deltoides×Populus nigra）生物量分配格局及其Pb富集特性的影响

采用速生树种修复重金属污染土壤的方法近年来受到越来越多关注,但已有结果存在很大不确定性。为了解杨树在不同Pb胁迫条件下生长响应和Pb富集效果,以长江上游两种典型土壤(酸性紫色土和钙质紫色土)为栽培介质,采用盆栽试验方法,研究了不同Pb浓度处理下(CK:0mg·kg-1;T1:200mg·kg-1;T2:450mg·kg-1;T3:2000mg·kg-1)欧美杂交杨(Populus deltoides×Populusnigra)生物量生产与分配格局以及Pb吸收、富集特性。两种土壤条件下杨树各器官生物量及总生物量均表现出随Pb胁迫程度的增加而降低的趋势,Pb胁迫条件下杨树生物量分配格局在钙质紫色土中表现为茎>粗根>叶>细根。相同浓度Pb处理条件下,单株杨树总生物量均表现为钙质紫色土大于酸性紫色土。随着Pb处理浓度的增大,杨树各器官Pb含量及积累量显著增加。Pb胁迫使杨树对Pb的富集系数逐渐增大而耐性系数逐渐减小。T3处理条件下杨树对Pb的富集系数在酸性紫色土中较大,且各处理条件下杨树对Pb的耐性系数均为酸性紫色土中较大。这些结果表明,高浓度Pb胁迫条件下酸性紫色土中的欧美杂交杨表现出较好的吸收和富集Pb的特性,这为Pb污染土壤的生物修复提供了一定的科学依据。

Effects of Pb Stress on Biomass Distribution Pattern and Pb Accumulation in Populus deltoids × Populus nigra

Fast-growing plants have been recently used in remediating metal-contaminated soil.In order to understand the growth of a poplar(Populus deltoides×Populus nigra) and its Pb accumulation in the upper Yangtze River Basin,a controlled pot-experiment cultivated with one-year old poplar was arranged with different treatments of four Pb supplies(CK:0 mg·kg-1;T1:200 mg·kg-1;T2:450 mg·kg-1;T3:2 000 mg·kg-1) under acid purple soil and alkaline purple soil.Biomass production and its distribution,Pb concentrations and accumulations in different components of the poplar were measured over one growing season.The biomass of poplar showed a decreased tendency with the increase of Pb supplies in both soils.Biomass distribution pattern under different Pb treatments in alkaline purple soil showed the same order as stems>coarse roots>leaves>fine roots.The total biomass was much higher in alkaline purple soil than that in acid purple soil under corresponding Pb treatment.Pb concentration and accumulation significantly increased with the increase of Pb supplies under both soils.An increased tendency of bioaccumulation coefficient(BC) but a decreased tendency of tolerance index(Ti) was observed with the increase of Pb supplies in both soils.BC of the poplar in acid purple soil under the treatment of T3 and Ti of the poplar in acid purple soil under all the treatments were much higher.The results suggested that the examined poplar showed better accumulation and translocation characteristics in acid purple soil under the higher Pb-contaminated environment,which provided efficient scientific evidences for phytoremediation in Pb-contaminated environment in the upper Yangtze River Basin.