重金属铅镉对洋葱根系生长的影响

针对土壤重金属污染影响作物生长和食品安全的问题，采取水培法，研究在不同种类和不同浓度重金属胁迫下，洋葱根系、根尖细胞有丝分裂、过氧化物酶(POD)和过氧化氢酶(CAT)活性等生理指标的变化，总结重金属对洋葱根系影响的机制。结果表明：铅和镉对洋葱根系的生长均有抑制作用，且随着浓度的增大而增强；在铅和镉胁迫下洋葱根尖细胞大部分处于有丝分裂的间期和前期；较高浓度的铅、镉使洋葱根尖细胞的细胞核畸变；POD酶、CAT酶活力随着镉浓度的增加而增加，随着铅浓度的增加而降低。洋葱根系能对重金属铅、镉的胁迫产生相应的生理响应机制，为重金属污染对植物影响的研究提供了理论基础和客观依据。

Effects of Heavy Metals Pb and Cd on Root Growth of Onion

In view of the impacts of heavy metal pollution of soil on crop growth and food safety, by adopting water culture method, the changes in physiological indexes such as mitosis, peroxidase (POD) and catalase (CAT) activities of onion roots and root tip cells under different kinds and concentrations of heavy metals were studied, with the mechanism of heavy metals on onion roots summarized. The results showed that Pb and Cd inhibited the growth of onion roots, which increased with the increase of the concentration. Under Pb and Cd stress, most of onion root tip cells were in the interphase and prophase of mitosis. Higher concentration of Pb and Cd made the nuclei of onion root tip cells distorted; The activities of POD and CAT increased with the increase of Cd concentration, but decreased with the increase of Pd concentration. Onion roots could produce corresponding physiological response mechanism to the stress of heavy metals of lead and cadmium, which provided theoretical basis and objective basis for the study of heavy metal pollution on plants.