昆虫取食对杨树富集Cd、Cu、Zn能力的影响

为探讨昆虫取食对杨树富集Cd、Cu、Zn能力的影响,对1年生小黑杨(Populus simonii×P.nigra)扦插盆栽苗,分别人工施加一定量的Cd、Cu、Zn,待苗木生长30 d后,接种舞毒蛾(Lymantria dispar)幼虫,取食14 d取出,7 d后取样,分析小黑杨根、茎、叶的干质量、重金属质量分数、富集系数、转运系数、贮存量。结果发现:各处理间根(8.0%~19.7%)、茎(61.0%~69.7%)、叶(17.3%~26.1%)干质量占植株的比例较为一致,不受重金属胁迫或重金属+昆虫取食胁迫影响。在Cd胁迫或Cd+昆虫取食胁迫下,小黑杨各部位对Cd的富集量及贮存量未产生显著响应。在Cu、Zn胁迫下,小黑杨根茎叶对Cu、Zn的富集量极显著增加(P0.01)、贮存量显著增加(P0.05);在Cu、Zn胁迫叠加昆虫取食胁迫后,对Cu、Zn的富集量及贮存量显著降低(P0.05),但其在小黑杨各部位的分布状况不变。Cd在小黑杨各部位的富集量比较相近,Cu主要在茎部,Zn主要在叶部。Cd、Cu在茎部贮存量最高,达总贮存量的50%以上,而Zn量主要贮存在茎、叶部,达总贮存量的80%以上。各处理组的转运系数(TF)由大到小为Zn、Cd、Cu,Zn胁迫降低了小黑杨的TF,Cd、Cu胁迫增加了小黑杨的TF;昆虫胁迫增加了小黑杨对Cd和Zn的TF,降低了对Cu的TF。说明昆虫取食能显著影响杨树对重金属的富集能力。

Effects of Insect Herbivory on Cd,Cu and Zn Accumulation in Populus simonii×P.nigra

For exploring the effects of insect herbivory on Cd , Cu and Zn accumulation in the poplar ( Populus simonii×P.nigra) trees, we tested the one-year-old poplar potted cutting seedlings with various concentrations of heavy metal exposures .After 30-d heavy metal treatments , the gypsy moth ( Lymantria dips a) larvae were added to the seedlings , and allowed to feed on the foliages for consecutive 14 d before removal from the tested seedlings .The dry weights , heavy metal concentraions , bio-concentration factors (BCF), translocation factors (TF) and storage capacities of the potted cutting seedlings were sampled and analyzed for 7 d after the larval removal .The dry weight percentages of roots (8%-19.7%),stems (61.0%-69.6%) and leaves ( 17.3%-26.1%) were relatively consistent among the treatments , and they were not affected by heavy metal stress or by insect herbivory .Cd stress alone ,or Cd plus insect herbivory did not show significant effects on the bio -concentration factors ( BCF) and Cd storage capacities of the seedlings .Under the stress of Cu and Zn, accumulations of Cu and Zn in the seedling roots , stems and leaves were increased significantly ( P<0.01 ) , so did their storage capacities ( P<0.05 ) . However , insect herbivory by the gypsy moth larvae on the Cu or Zn stressed seedlings significantly decreased the accumu -lation and storage capacity of Cu and Zn (P<0.05) in all seedling parts.The amounts of Cd accumulation was similar a-mong roots, stems and leaves of the popar seedlings .Cu was mainly concentrated in the stems , while Zn was mostly accu-mulated in the leaves .The storage capacities of Cu and Cd in the stems were the highest , exceeding 50%of the total stor-age capacity.The storage capacity of Zn was highest in the stems and leaves , accouting for above 80%of the total storage . The descending order of transfer factor ( TF) in metal treatment groups was Zn , Cd and Cu.The Zn stress reduced the TF of the potted cutting seedlings , whereas , the stress of Cd or Cu increased the TF .Insect herbivory by the gypsy moth larvae increased the TF of Cd and Zn , but reduced the TF of Cu .Thus, the accumulation of heavy metal by the poplar seedlings was significantly affected by insect herbivory .