镉胁迫下增施氮对白三叶草生长的影响和镉毒害的缓解效应研究

摘要

为了解镉(Cd)胁迫下施加外源氮对植物生长生理的影响及解毒机理,本研究采用盆栽试验,以白三叶草为材料,研究了在重金属镉(CdCl2·2.5H2 O)胁迫下施加氮[CO(NH2)2]对其生长、叶绿素含量、抗氧化酶活性、镉含量、谷胱甘肽(GSH)和植物络合素(PCs)含量的影响.结果表明,单独的Cd处理显著抑制白三叶草生长及叶绿素的合成;而镉胁迫下施加氮显著促进了白三叶草的生长,其生物量和叶绿素含量显著提高.同时,镉胁迫下增施氮显著提高了植株过氧化物酶(POD)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性及白三叶草植株体内镉含量.单独镉处理显著增加了PCs含量,GSH含量显著降低;而镉胁迫下增施氮使GSH和PCs含量均显著增加.由此说明,外源氮素在植物对重金属镉的解毒过程起到了重要的作用,缓解了镉对白三叶草的毒害.%We investigated the effect of exogenous nitrogen on the growth of white clover (Trifolium repens) under cadmium stress and on Cd toxicity.White clover plants grown in pots were treated with N and/or Cd,and their growth,biomass,chlorophyll content,antioxidant enzyme activity,Cd content,glutathione (GSH) content,and phytochelatins content were determined.Treatment with Cd significantly inhibited the growth and decreased the chlorophyll content of white clover.However,applications of both Cd and N to the soil promoted white clover biomass and chlorophyll content,as compared with the control.The addition of N under Cd stress enhanced plant growth and chlorophyll content,and increased the activities of peroxidase,superoxide dismutase,and catalase,as well as increasing the Cd content.Treatment with Cd alone increased the phytochelatins content and significantly reduced the GSH content.Treatment with N increased the GSH and phytochelatins contents under Cd stress.These results indicated that exogenous N can effectively alleviate Cd toxicity to white clover.