铅和镉胁迫对黄瓜种子萌发期间的毒害效应

以津研四号黄瓜为材料,研究0.5、1.5、2.5、4.0 mmol/L Pb(NO3)2和0.5、1.0、1.5、2.0 mmol/L CdCl2处理对其种子萌发期间的毒害效应。结果表明:与对照(去离子水处理)相比,随着Pb、Cd浓度的增高,黄瓜胚根及胚芽生长受到的抑制显著加大;同一浓度的Pb、Cd处理,胚根生长受到的抑制作用较胚芽更为明显;Pb、Cd胁迫7 d后,黄瓜幼苗平均长度、平均鲜重及子叶中叶绿素含量随Pb、Cd浓度的增大而明显降低;透射电镜观察表明,Pb、Cd处理4 d后,幼苗根尖细胞超微结构变化异常明显,主要表现为细胞间隙增大、核染色质外溢、线粒体数量和脊突明显减少直至消失,细胞内部各细胞器膜系统结构严重破坏直至解体消失,细胞壁部分断裂,细胞结构解体,由镉引起的毒害效应较铅更为严重。

Poison effect of Pb and Cd stress on cucumber seeds during the course of germination

"Number four jinyan" seeds were chosen to study the poison effect of 0.5,1.5,2.5,4.0 mmol/L Pb(NO3)2 and 0.5,1.0,1.5,2.0 mmol/L CdCl2 on cucumber seeds during the course of germination.The results showed compared to the CK,the inhibition on growth of radicle and germ significantly increased with increasing concentration of Pb and Cd.The growth of the radicle was more significantly inhibited by Pb and Cd stress.After seven days of stress,the average length,fresh weight of seedling and the chlorophyll content of cotyledons obviously decreased with the increase of the concentration of Pb and Cd.The result observed through transmission electron microscope showed ultrastructural changes of root tip cells of seedling were unusually apparent after four days of stress,which were characterized by cell gap increasing,chromatin spilling,reducing and eventually disappearing of the mitochondria and crest.Inside the cells,the membrane structure of each organelle was severely damaged until disintegrated and disappeared.The cell wall was partly fractured and the cell structure was collapsed.The poisoning effect caused by Cd was more serious than that caused by Pb under the same experimental conditions.