镉胁迫对玉米幼苗光合特性及活性氧代谢的影响

Effects of Cadmium Stress on Photosynthetic Characteristics and Active Oxygen Metabolism of Maize Seedling

为探究Cd^(2+)胁迫对玉米幼苗光合特性及活性氧代谢的影响,以玉米‘农大108’为试验材料,用0、100、200、400μmol·L^(-1)CdCl_(2)溶液处理玉米幼苗72 h。结果表明:Cd^(2+)在幼苗中快速积累,积累量为根>茎>叶;Cd^(2+)引起叶片萎蔫,单株干质量、叶绿素含量、净光合速率(Pn)、蒸腾速率(Tr)和气孔导度(Gs)急剧降低,叶间CO_(2)浓度(Ci)显著升高;Cd^(2+)胁迫引起叶片中SOD和CAT活性先升后降,GSH含量逐渐降低;叶片中H_(2)O_(2)和MDA含量随Cd^(2+)胁迫持续升高。综上,Cd^(2+)胁迫引起玉米叶片氧化胁迫和膜结构损伤,光合作用、呼吸作用和蒸腾作用受阻;叶片功能丧失,植株萎蔫甚至死亡。

To investigate the effects of Cd^(2+)on the photosynthetic characteristics and active oxygen metabolism of maize seedlings,seedlings(Zea mays L.,cv.'Nongda 108')were treated with 0,100,200 and 400μmol·L^(-1)CdCl_(2)solution for 72 h.The results showed that the bioaccumulation of Cd^(2+)in the seedlings increased significantly,and such bioaccumulation of various organs decreased in turn:the root>the stem>the leaf.Chlorophyll content,dry weight per plant,the net photosynthetic rate(Pn),transpiration rate(Tr)and stomatal conductance(Gs)were decreased sharply,but intercellular CO_(2)concentration(Ci)increased significantly after Cd^(2+)stress.The activities of SOD and CAT initially increased and subsequently decreased with the increasing of Cd^(2+)concentrations and stress time,correspondingly,the content of GSH decreased gradually.MDA level in leaves was increased,in association with increased H_(2)O_(2)content after continuous Cd^(2+)stress.In conclusion,Cd^(2+)stress causes oxidative stress and membrane structure damage,which causes loss of leaf function,plant wilting and even death.