镉锌复合污染对龙葵苗期生长和镉锌累积特性的影响

Growth and Heavy Metal Accumulation in Solanum nigrum L. Seedlings with Cd-Zn Complex Pollution

采用营养液培养法研究了苗期龙葵(Solanumnigrum L.)对镉锌复合污染的反应及其对镉锌的吸收和积累特性.结果表明:(1)高浓度镉(200μmol·L-1)、锌(500μmol·L-1)胁迫使苗期龙葵植株生长受到严重抑制,但低浓度镉锌复合处理的部分植株生物量甚至超过了对照.(2)添加锌对苗期龙葵地上部镉积累有显著的影响(P<0.05);当锌浓度为100μmol·L-1时,镉积累量达到峰值,其中的100Cd/100Znμmol·L-1处理组合的镉积累量为所有处理中的最大值(地上部积累量高达171.31μg·plant-1);当锌浓度增加到500μmol·L-1时,植株体内镉积累量则呈现下降趋势.(3)添加镉对苗期龙葵地上部锌积累也有显著的影响(P<0.05);当镉浓度达50μmol·L-1时,根、茎、叶中锌积累量均达到最高值;当镉浓度为200μmol·L-1时,各处理单株地上部锌积累量最低.(4)从植株整体的镉、锌积累量来看,苗期龙葵地上部镉积累量最高达根系的14.67倍,而其锌积累量最高达根系的13.59倍.研究发现,龙葵幼苗根系、茎和叶中镉、锌含量随营养液中镉、锌浓度的增加而显著增加(P<0.05);添加锌在一定程度上缓解了镉对苗期龙葵的毒害效应,低浓度锌还可以提高植株对镉的吸收和积累;添加镉在一定程度上增强了植株对锌的耐受性和吸收富集能力;植株地上部的镉、锌积累量明显高于根系.

In the present study, the growth and metal accumulation of Solanurn nigrum L. were examined under cadmium-zinc complex polluted conditions using nutrient solution culture method. The results showed as following.（1） high concentration of Cd （200μmol ·L^-1） and Zn （500 μmol ·L^-1） greatly affected the growth of S. nigrum seedlings,but dry biomass of part Cd-Zn treated plants were higher compared with CK plants under low concentrations of Cd-Zn. （2）Cd and Zn concentrations of root, stem and leaf in S. nigrum seedlings significantly increased with the application of Cd and Zn in the nutrient solution （P〈0.05）. Cd concentration reached maximum when applied 100 μmol· L^-1 Zn, especially the shoot Cd concentration reached peak value 171.31μg·plant^-1 when Cd/Zn ratio was 100/100μmol ·L^-1 ,and it.decreased along with 500 μmol Zn · L^-1 （3）The application of Cd significantly influenced the shoot Zn concentration of S. nigrum seedlings. Zn concentrations of root, stem and leaf in S. nigrurn seedlings reached maximum when 50μmol ·L^-1 Cd was applied （P〈0. 05） ,and shoot Zn concentration in all treated plants reached the lowest when applied 200μmol ·L^-1 Cd in the solution. （4）Cd and Zn concentrations were related to different tissues of S. nigrum seedlings. From the view of total heavy metal concentrations,maximum shoot Cd concentration was 14.67-fold of that in root,and Zn concentration was 13.59-fold of that in root. In conclusion,Zn application could alleviate Cd toxic effect on the growth of S. nigrum seedlings and low concentration （≤100μmol ·L^-1 ） of Zn could promote the absorption and accumulation of Cd. Cd also could improve Zn tolerance and Zn absorption and accumulation in some extent.