香根草对污染土壤水溶态重金属组分胁迫响应研究

为探讨香根草对污染土壤中水溶态重金属组分在时间尺度上的胁迫响应,以Pb和Cu复合污染土壤为研究对象,通过种子萌发试验和水培试验,模拟重金属水溶态组分对香根草种子萌发、幼苗生长情况及重金属积累特性的影响。结果表明,Pb和Cu水溶态组分显著降低香根草幼苗的根长、株高、鲜质量和干质量。其中,根长受抑制作用最显著,在第60 d,处理组根长比对照组低43.6%;香根草幼苗的重金属耐性指数(MTI)总体上随生长时间增加呈上升趋势,第60 d的MTI为70.2%;香根草幼苗可显著富集Pb和Cu,且主要累积在根部,其转运系数(TF)低至0.02和0.10,根部最大积累量分别达到763 mg·kg~(-1)和235 mg·kg~(-1),表明香根草属于根部积累性植物。由此可见,香根草幼苗对水溶态重金属组分的耐受能力随其生长时间的增加而逐渐增强,利用香根草进行重金属的植物固定具有较大潜力。

Response of Vetiveria zizanioides to the stress of water-soluble components of heavy metals in contaminated soil

This study investigated the response of vetiver grass(Vetiveria zizanioides)to the stress of water-soluble components of heavy metals in contaminated soil at a time scale. Seed germination and hydroponic experiments were conducted to simulate the effects of the water-soluble components of Pb and Cu in contaminated soil on seed germination, seedling growth, and heavy metal accumulation of vetiver. Results showed that the water-soluble components of Pb and Cu significantly reduced the root length, shoot height, fresh weight, and dry weight of the vetiver seedlings. Among the affected growth indexes, the inhibitory effect was most significant on the root length, which was as much as 43.6% shorter than in the control on the 60^th day. The metal tolerance index(MTI)of the vetiver seedlings increased with the growth time and reached 70.2% on the 60^th day. Furthermore, Pb and Cu were significantly absorbed and enriched by the vetiver seedlings; they were mainly accumulated in the roots, with a translocation factor(TF)as low as 0.02 and 0.10 for Pb and Cu, respectively. The maximum accumulations of Pb and Cu in the roots were 763 mg·kg^-1 and 235 mg·kg^-1, respectively, indicating that vetiver tends to accumulate metals in its roots instead of its shoots. Thus, it was determined that the tolerance of vetiver seedlings to water-soluble components of heavy metals increases with the growth time, suggesting their great potential for metal phytostabilization.