采用水培法,对 Pb 和 Cd 单一及复合胁迫(500 mg· L^-1 Pb、25 mg· L^-1 Cd、500 mg· L^-1 Pb-25 mg· L^-1 Cd)条件下溪荪(Iris sanguinea Donn ex Horn.)幼苗不同部分的生长及 Pb、Cd、Zn、Cu、K 和 Na 积累状况进行了研究。 结果显示:在 Pb 单一胁迫条件下,溪荪幼苗地下部分干质量较对照降低了 18. 2% ,地上部分干质量和耐性指数均与对照无显著差异;在 Cd 单一胁迫条件下,地下部分与地上部分的干质量较对照分别降低了 16. 4% 和 14. 1% ,耐性指数降低了 7% ;在 Pb-Cd 复合胁迫条件下,溪荪幼苗不同部分的干质量以及耐性指数均与对照无显著差异。 在 Pb单一及 Pb-Cd 复合胁迫条件下,幼苗不同部分的 Pb 含量均明显高于对照, Pb 单一胁迫处理组幼苗地上部分和地下部分的 Pb 含量分别比 Pb-Cd 复合胁迫处理组高 19. 8% 和 16. 0% 。 在 Cd 单一及 Pb-Cd 复合胁迫条件下,幼苗不同部分的 Cd 含量均明显高于对照,Pb-Cd 复合胁迫处理组幼苗地上部分和地下部分的 Cd 含量分别为 Cd 单一胁迫处理组的 2. 02 和 5. 74 倍。 经 Pb 和 Cd 单一及复合胁迫后,幼苗不同部分的 Zn、Cu 和 Na 含量均明显高于对照,而 K 含量则低于对照;地上部分的 Zn、K 和 Na 含量均高于地下部分,但 Cu 含量在幼苗不同部分的变化趋势则有所不同。 比较结果表明:Pb-Cd 复合胁迫对溪荪幼苗的 Pb 积累有促进作用、对 Cd 积累有抑制作用,表现出拮抗作用;溪荪对 Pb 胁迫的耐性相对更强,对 Pb 和 Cd 及其他金属元素有一定的积累能力,可用于 Pb 污染环境尤其是湿地 Pb 污染环境的修复。

 

The status of growth and accumulations of Pb, Cd, Zn, Cu, K and Na in different parts of Iris sanguinea Donn ex Horn. under single and combination stresses of Pb and Cd (500 mg· L^-1 Pb, 25 mg· L^-1 Cd, 500 mg· L^-1Pb-25 mg· L^-1Cd) were studied by water culture method. The results show that dry weight of under-ground part under Pb single stress decreases by 18. 2% compared with the control, while dry weight of above-ground part and tolerance index have not significant difference with the control. Under Cd single stress, dry weights of under- and above- ground parts decrease by 16. 4% and 14. 1% , and tolerance index decreases by 7% , respectively, compared with the control. Under Pb-Cd combination stress, all of dry weights of different parts and tolerance index of I. sanguinea seedlings are not significantly different with the control. Pb content in different parts of seedlings under Pb single and Pb-Cd combination stresses is obviously higher than that of the control. And Pb content in above- and under- ground parts of seedlings in Pb single stress group increases by 19. 8% and 16. 0% , respectively, compared with that in Pb-Cd combination stress group. Cd content in different parts of seedlings under Cd single and Pb-Cd combination stresses is obviously higher than that of the control. And Cd content in above- and under- ground parts of seedlings in Pb-Cd combination stress group is 2. 02 and 5. 74 times, respectively, to that in Cd single stress group. Under single and combination stresses of Pb and Cd, contents of Zn, Cu and Na in different parts of seedlings are obviously higher but K content is lower than those of the control. And contents of Zn, K and Na in above-ground part are higher than those in under- ground part, while change trend of Cu content in different parts of seedlings is different. The comparison results indicate that Pb-Cd combination stress may promote Pb accumulation and inhibit Cd accumulation of I. sanguinea seedlings, appearing an antagonism effect. I. sanguinea has a relatively stronger tolerance to Pb, and also has a certain accumulation ability to Pb and Cd as well as other metal elements. Therefore, I. sanguinea can be used for remediation of Pb pollution environment especially marsh Pb pollution environment.