不同形态氮肥施用对鱼腥草吸收转运Pb的影响

Effects of Nitrogenous Fertilizers on Accumulation and Transfer of Lead by Houttuynia cordata Thunb

通过土培试验研究了不同形态氮肥施用对鱼腥草吸收转运Pb的影响。结果表明,在相同浓度Pb处理下,施用铵态氮肥可促进鱼腥草生长,从而降低重金属Pb对鱼腥草的毒害;施用硝态氮肥时,更有利于鱼腥草体内的Pb2+由根部向茎部转移。低浓度Pb处理时,增加硝态氮肥施用量可降低鱼腥草对Pb的积累能力;高浓度Pb处理时,铵态氮的施用则对鱼腥草积累Pb量具有一定的抑制作用。

Rational application of fertilizer can promote the growth of plant, also enhance its yield and improve its quality. Meanwhile, it is one of the main techniques for enhancing the efficiency of phytoremediation. Pot experiment studies were conducted on soil treated by lead to probe the effect of different concentrations and forms of nitrogen fertilizers （NH^＋ 4-N and NO^- 3N） on the accumulation and distribution of lead in Houttuynia cordata Thunb. The results indicated that under the same concentration of Pb, the application of NH^＋ 4-N fertilizer could promote the growth of Houttuynia cordata Thunb better than that NO^- 3N, and, thus lessening the toxicity of Pb. When the application rate of NH^＋ 4-N was 250 mg· kg^-l, the root weight, shoot weight and leaf weight ofHouttuynia cordata Thunb were higher than those under other treatments. Meanwhile, applying NO^- 3-N was better for the transportation of Pb^2＋ from root to shoot in Houttuynia cordata Thunb, and increased the accumulation amount of Pb in above ground. These results varied with treatment concentrations of Pb： under the low concentration of Pb, increasing the application of NO3-N could reduce the accumulation ability of Houttuynia cordata Thunb to Pb, with the smallest enrichment coefficient of Pb in Houttuynia cordata Thunb at 150 mg· kg^-1 of NO^- 3-N, while, under the high concentration of Pb, applying NH^＋ 4-N could inhibit the accumulation amount of Pb in Houttuynia cordata Thunb to some degree, with the smallest enrichment coefficient of Pb at 250 mg· g^-l of NH^＋ 4-N. This research is important to direct the reasonable exploitation of the Chinese herbal medicine Houttuynia cordata Thunb.