Effects of heavy metal ions on seeds germination and radicle growth of Brassica napus

Heavy metals had different effects on seed germination and radicle growth.Toxicity of five types of heavy metal ions (Hg2+,Cd2+,Ni2+,Co2+ and Zn2+) on the initial growth of Brassica napus and whether the application of K+,Mg2+ and Ca2+ could alleviate the effects of heavy metals on the seeds germination and radicle growth of B.napus were investigated.The results showed that radicle growth was more sensitive to heavy metals than seed germination.Zn2+ was not very toxic to seed germination but was to radicle growth.Hg2+ was the most toxic metal for plant growth and development.K+ and Ca2+ slightly alleviated the toxicity of Ni2+,Zn2+ and Co2+ to seed germination,while slightly increased the toxicity of Hg2+ and Cd2+.Mg2+ was effective to reduce the toxicity of Ni2+,Zn2+,Cd2+ and Co2+ on seed germination,but was not influence to Hg2+.The toxicity of Ni2+,Hg2+,Cd2+ and Co2+ on radicle growth was partially enhanced in the present of 5 mmol/L K+ and Mg2+ while Ca2+ partially restored the inhibition of Zn2+,Ni2+ and Co2+.The researches are helpful for further research on elucidating fundamental mechanism of heavy metal tolerance and cultivating plants on heavy-metal-contaminated soil