柽柳对镉胁迫的生理生态响应  

ECOPHYSIOLOGICAL RESPONSE OF TAMARIX LAXA TO CADMIUM STRESS

作　　者：丁效东[1] 高东瑞[1] 冯固[1] 

机构地区：[1]中国农业大学资源与环境学院,教育部植物-土壤相互作用重点开放实验室,北京100094

出　　处：《植物生态学报》2007年第1期145-149,共5页Chinese Journal of Plant Ecology

基　　金：教育部科学技术研究重点项目(105012)

摘　　要：在温室条件下采用营养液培养的方法研究了营养液中Cd^2＋浓度为0、10、50、200和500μmol·L^-1时，柽柳（短穗柽柳（Tamarix laxa））对重金属镉的吸收和分泌特点。研究结果表明：与对照相比，较低浓度（10μmol·L^-1）镉处理对柽柳的生长量、含水率均没有显著变化，两周培养期间内没有出现镉中毒症状；Cd^2＋浓度增加至50μmol·L^-1时对柽柳产生了较强的毒害作用，柽柳的生长量、植株含水率均明显下降，在加镉处理第十二天时营养枝开始发黄，出现镉中毒症状。柽柳不同器官镉积累量由大到小依次为：根系〉新生营养枝〉枝条。研究还发现，柽柳盐腺能够分泌镉，分泌镉的量占营养枝中镉含量的0．5％左右；在较低浓度（0～50μmol·L^-1）时柽柳对镉的分泌量随着培养液中Cd^2＋浓度的增加而增加，并在50μmol·L^-1镉处理时，分泌物中Cd^2＋浓度达到本试验中的最高点，然后镉的分泌量开始下降。这一结果说明，尽管泌盐盐生植物——柽柳的盐腺能够分泌重金属镉，但是其数量在植株累积的镉总量中所占甚少，对短穗柽柳耐镉毒害能力贡献不大。Aims Excretion of salt by gland had been studied, but the response of salt glands to heavy metals was rarely explored. A hydroponic cultivation experiment was conducted in glasshouse with excretohalophyte to investigate ： 1） if salt gland is able to excrete Cd^2＋ ions, 2） extent of Cd^2＋ tolerance for secretohalophyte, and 3） possible mechanisms by which the excretohalophyte is able to resist Cd^2＋ stress. Methods Branches of Tamarix laxa plants were cut into 15 cm sections and propagated for 3 months. They were then transferred into hydroponic cultivation with a Hoagland＇ s nutrient solution for 20 days and treated with 0, 10, 50, 200 and 500 μmol·L^-1 Cd^2＋ for 2 weeks to determine the uptake and excretion of Cd^2＋ . Important findings There were no significant differences in the relative growth rate or water content of the plants between the treatment with 10 μmol·L^-1 Cd^2＋ and the control. When Cd^2＋ levels exceeded 50 μmol·L^-1, the shoots of T. laxa suffered toxicity. Cd^2＋ excretion through salt glands was detected in all Cd^2＋-added treatments, but the total amount was lower, although the amount of secreted Cd^2＋ from salt gland was increased with increasing of Cd^2＋ levels. Salt glands excreted Cd^2＋ , but the secretion plays less important role in Cd^2＋ toxic resistance for excretohalophyte.

关 键 词：短穗柽柳 镉 盐腺 分泌 

分 类 号：Q945.78[生物学—植物学]