重金属胁迫对白三叶种子萌发的影响

为了探讨重金属胁迫对白三叶(Trifolium repens)种子萌发的影响,本研究模拟4种不同浓度重金属离子(Zn²⁺、Pb²⁺、Cu²⁺、Cd²⁺)条件,测定种子的发芽率、发芽势、发芽指数和相对胚根(芽)长等相关指标。结果表明:白三叶种子对Cd²⁺的耐受能力最强,Zn²⁺和Cu²⁺次之,对Pb²⁺的耐受能力最弱。总体上,种子的发芽率、发芽势、发芽指数和相对胚根(芽)长随着重金属离子浓度的增加表现出不同程度的下降趋势。高浓度重金属离子对白三叶种子萌发及生长发育会产生严重的阻碍作用。然而,低浓度的Zn²⁺、Cu²⁺、Pb²⁺对胚的生长具有一定促进作用,表明白三叶对低浓度重金属环境有一定适应性。在本试验中,白三叶对Cd具有较强的耐受能力,5种不同浓度的Cd²⁺条件下种子的发芽率均高于50%,且Cd²⁺浓度为1mg/L时可促进种子的萌发。此外,进行过重金属处理的种子会表现出相对胚根长小于相对胚芽长,表明重金属胁迫首先影响种子根部的生长发育,从而抑制白三叶的生长。综上所述,白三叶对低浓度的Zn²⁺、Pb²⁺、Cu²⁺、Cd²⁺和高浓度Cd²⁺具有较好的耐受能力,可作为上述环境的绿化植被,并且在重金属Cd土壤污染中有良好修复前景。

Effects of Heavy Metal Stress on Germination of Trifolium repens

In order to investigate the effect heavy metal stress on the seed germination of Trifolium repens ,this study simulated the conditions of four different concentrations of heavy metal ions (Zn^2+,Pb^2+,Cu^2+,Cd^2+)and determined the germination rate,germination potential,germination index and relative radicle (germ) length.The results showed that the strongest tolerance of Trifolium repens seed was Cd 2+,followed by Zn^2+ and Cu^2+,and the weakest tolerance was Pb^2+.In general,the germination rate,germination potential,germination index and relative radicle (germ) length of seed showed different degrees of decline with the increase of heavy metal ion concentration.At high concentrations,heavy metal ions could concentration seriously hinder the germination and growth of Trifolium repens seeds.However,low concentrations of Zn^2+,Cu^2+ and Pb^2+ had a certain promoting effect on embryo growth,indicated that Trifolium repens had certain adaptability to low concentration heavy metal environment. In this experiment, Trifolium repens had strong tolerance to cadmium environment.The germination rate of seeds were all higher than 50%,when the environmental concentration was 5 different concentrations of Cd^2+.And seed germination would be promoted under the Cd^2+ concentration was 1 mg/L.In addition,the seeds treated with heavy metal showed a relative radicle length less than the relative embryo length,it means that the heavy metal stress first affected the growth of the seed roots,and thereby inhibiting the growth of the Trifolium repens .In summary, Trifolium repens had good tolerance to low concentrations of Zn^2+,Pb^2+,Cu^2+,Cd^2+ and high concentrations of Cd^2+,which could be used as a green vegetation for the above environment,and had a good prospect for restoration in heavy metal Cd soil pollution.