商陆(Phytolacca acinosa Roxb.)的锰耐性和超积累

MANGANESE TOLERANCE AND HYPERACCUMULATION OF PHYTOLACCA ACINOSA ROXB.

超积累植物的确证对成功实施重金属污染环境植物修复是必不可少的。通过野外调查和营养液培养试验 ,研究超积累植物商陆 (PhytolaccaacinosaRoxb )的锰富集特性 ,结果表明 ,商陆对生长介质中的Mn具有很强的耐性和累积能力。商陆在锰含量高达 114× 10 3 mgkg-1的尾矿废弃地上依然生长良好 ,叶锰含量最高达 19 3× 10 3 mgkg-1。温室培养条件下 ,当生长介质中Mn浓度为 8 0 0 0mmolL-1时 ,虽然其生物量与对照相比有所降低 ,但植株仍能生长。随着生长介质中Mn浓度的升高 ,商陆叶和茎的Mn含量逐渐增加 ,生物富集系数则逐渐降低 ,但是地上部分锰积累量则先增加后减少。当Mn浓度为 5 0 0 0mmolL-1时 ,商陆地上部分锰积累量达到最大值 2 5 8 2mgplant-1;当Mn浓度为 12 0 0 0mmolL-1时 ,商陆仍能完成整个生命周期 ,叶锰含量达到最大值 36 4× 10 3 mgkg-1,生物富集系数为 5 5。不同锰供应水平下 ,商陆吸收的锰有87%～ 95 %被转移到地上部分。这进一步验证商陆的锰超积累特性 ,为利用超积累植物对大面积污染土壤实施植物修复提供了有力证据 。

Identification of new hyperaccumulators is of great importance to successful phytoremediation of the environment contaminated with heavy metal. A new manganese hyperaccumulator plant, Phytolacca acinosa Roxb., was found growing in Southern China through field surveys on Mn mine tailings dumps and greenhouse experiments. This species has not only remarkable tolerance to Mn, but also an extraordinary capacity for this element. With the maximum Mn concentration in the leaf reaching 19 300 mg kg -1, the plant grew well on Xiangtan Mn tailings dump with Mn concentration being as high as 114 000 mg kg -1. Under hydroponic conditions, the manganese concentration in the plant leaves could reach as high as 36 380 mg kg -1 with the bioaccumulation coefficient of 55 at a Mn supply level of 12.000 mmol L -1. P. acinosa could grow quite well hydroponically with Mn supplied at a level of 8.000 mmol L -1, although its biomass was less than the plant's in control with Mn supplied at 0.005 mmol L -1. With the Mn concentration in the media increasing, the manganese concentration in the shoots increased, but the bioaccumulation coefficient gradually decreased. The total Mn accumulated in the aerial parts of the plant rose first and then declined. At the Mn concentration in the solution reached 5.000 mmol L -1, the Mn accumulation in the aerial parts of the plant was the highest (258.2 mg plant -1). Partitioning of Mn between the aerial parts and the roots showed that 87%～95% of Mn was transported into the former in all the treatments of the experiment, demonstrating the great capacity of the plant transporting Mn from the roots to the aerial parts. P. acinosa therefore offers great potential for use in phytoremediation of Mn-contaminated soils and waters.