铅对榧树幼苗生长及生理特性的影响

Effect of Lead Stress on Growth and Physiological Properties in Torreya grandis Seedlings

2013年,以2年生无污染的榧树实生苗为材料,以Pb(NO3)2的形式加入,设置0,700,1 400 mg·kg^(-1) 3个处理浓度。处理60 d后,测定苗高、地径、生物量及光合和生理指标。结果发现,700 mg·kg^(-1)的Pb处理促进榧树幼苗生长,表现在总生物量、苗高和地径等生长指标均显著高于对照组(P<0.05);幼苗叶片的净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)皆显著高于对照(P<0.05);叶绿体超微结构与对照相比无显著差异,超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)活性较对照明显下降(P<0.05)。与对照相比,1 400 mg·kg^(-1)的Pb处理则抑制榧树幼苗生长,幼苗生物量、苗高和地径以及Pn,Gs和Tr皆显著低于对照(P<0.05),且发生叶绿体超微结构破坏,嗜锇颗粒增多变大的现象;叶片的超氧阴离子(O_2^(·-)),过氧化氢(H_2O_2)和丙二醛(MDA)含量显著上升,SOD,CAT,POD活性较对照明显上升(P<0.05),表明对榧树幼苗产生了胁迫,抑制了生长和光合作用,导致活性氧自由基的积累、膜脂过氧化加剧和抗氧化酶活性的增加。

Experiments were conducted on2-year Torreya grandis seedlings treated by different concentrations of Pb namely0(control),700and1400mg/kg in2013.60days later,determinations were implemented on seedling height,ground diameter,biomass,photosynthetic and physiological parameters such as net photosynthetic rate(Pn),stomatal conductance(Gs),etc.The result showed that700mg·kg-1Pb treatment could significantly promote growth of seedlings,with more biomass,height growth and ground diameter than that of the control,as well as Pn,Gs and transpiration rate(Tr).Ultrastructure of chloroplast had no evident difference with that of the control,but activities of superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT)decreased significantly.The treatment of1400mg/kg of Pb inhibited the growth,with less biomass,height growth and ground diameter than that of the control,and also Gs and(Tr).Ultrastructure of chloroplast was damaged,and superoxide anion(O2.-),H2O2andmalondialdehyde(MDA)increased evidently,as well as SOD,POD and CAT,compared with that of the control.