Abstract: The study on the toxicity of heavy metals Hg²⁺,Cd²⁺,Cu²⁺ and Pb²⁺ to Arabidopsis seed germination and seedling growth showed that the test heavy metals had a stronger toxicity on seedling growth than on seed germination.The toxicity on seedlings was in order of Cu²⁺>Hg²⁺>Cd²⁺/Pb²⁺,while on seeds was Hg²⁺>Cd²⁺>Pb²⁺/Cu²⁺.Seed germination rate was decreased with increasing stress duration,and different heavy metals showed different toxicity at different stress duration.For example,Hg²⁺ displayed a stronger toxicity at 12～24 h stress,while Cd²⁺ was at 0～12 h stress.It seemed that seed coat played an important role in seed tolerance to heavy metals.The interaction between non-toxic ions and heavy metal ions on seed germination showed that Ca²⁺,Mg²⁺,K⁺ and Na⁺ at 5 mmol·L^-1could enhance the toxicity of Hg²⁺,but did not affect Cd²⁺ toxicity.For seedling growth,Ca²⁺,Mg²⁺,K⁺ and Na⁺ might enhance the toxicity of Hg²⁺,Ca²⁺ might alleviate the toxicity of Cd²⁺ but enhance the toxicity of Cu²⁺,and K⁺ might alleviate Pb²⁺ toxicity.The mechanism of heavy metals injury was discussed in the paper.

Key words: Seed germination, Seedling growth, Arabidopsis