铅污染对青杨雌雄幼苗铅富集和营养特征的影响

Effects of Pb Pollution on Accumulation of Pb and Nutrient Status of Female and Male Cuttings of Populus cathayana

该研究以青杨雌雄幼苗为实验材料,采用盆栽控制实验的方式,设置20.5(CK)、50(T1)和100mg·kg-1(T2)3个铅浓度水平,分析面源水平铅污染条件下青杨性别间铅的积累和营养状况的差异。结果表明:(1)与CK相比,面源水平铅污染条件下,青杨雄株幼苗的总生物量未受到显著影响,雌株总生物量显著降低,但相同处理条件下雌株生物量均显著高于雄株。(2)2个梯度的铅污染均未显著影响两种性别青杨各器官中N的浓度,且雌雄间的性别差异不显著,但T2处理一定程度降低了两种性别各器官中P的浓度;与CK相比,雄株在受铅胁迫处理时N/P逐渐增加,说明此时雄株的生长可能会逐渐受到P素营养缺乏的影响。(3)随着铅处理浓度的增加,青杨雌株幼苗对铅的积累总量逐步增加,但雄株的积累总量的增加却不显著。可见,青杨雄株在面源水平铅污染条件下的抗性和耐受性优于雌株;雌雄青杨对土壤铅污染有不同的适应策略,雌株对铅的积累策略是其生物量下降以及营养平衡受到影响的主要原因,雄株对铅低吸收的策略使其更适应在铅污染区域生长。

Populus cathayana,a native species,is a typical dioecious and fast-growing woody species,which extensively distributed in China,exhibiting good adaptivity to local climates.In the present study,a controlled experiment was conducted to detect differences in Pb accumulation and nutrient status between male and female cuttings of P.cathayana,when exposed to diffused levels of Pb pollution.One-year old shoots of both sexes of P.cathayana were selected as experimental materials,and each cutting was cultivated in one pot.In our study,three levels of Pb pollution（CK：20.5 mg·kg^-1;T1：50 mg·kg^-1;T2：100 mg·kg^-1）were set up.The experiment lasted a grown season（from June 2013 to October 2013）.The result showed that：（1）The diffused levels of Pb pollution（T1and T2）significantly decreased total biomass of females,but not for that of males.However,in all corresponding treatments,the total biomass of females was significantly higher than that of males.（2）Both levels of Pb pollution（T1and T2）did not negatively affect N concentration in all organs of both sexes,and there was no significant difference in N concentration between the sexes.In contrast,the response of P concentration in both sexes was more obvious than that ofNconcentration,especially when exposed to the treatment T2.The treatment T2 decreased the P concentration in different organs of both sexes to some degree when compared to the control.When compared to the control,the decrease of N/P ratio in males suggested that growth of males would be restricted by shortage of P gradually.（3）When comes to accumulation capacity of Pb,the total Pb accumulation increased gradually in females,but not in males,along with increasing level of Pb pollution.In conclusion,our results indicated that males＇ capacity in resistance and tolerance against lead pollution is greater than females,and there is sex-specific adaptive strategy in response to lead pollution.The higher accumulation of Pb in females might be main reason for decreasing its biomass and imbalance in nutrient status,while lower accumulation in males might be in favor for its adaptivity to Pb-contaminated environments.