不同氮形态对东南景天镉积累的影响

Effects of different nitrogen forms on cadmium accumulation of Sedum alfredii Hance

通过水培试验,研究不同氮形态对2种生态型东南景天生长和镉吸收积累的影响.结果表明,外加(NH4)2SO4、Ca(NO3)2或NH4NO3均能显著提高超积累生态型东南景天地上部生物量及叶绿素含量,且无论在低镉(10μmol·L-1)还是高镉(100μmol·L-1)条件下,以(NH4)2SO4处理的增幅最大.不同氮形态对2种生态型东南景天地上部镉含量没有显著影响,而在一定程度上提高了根系镉的含量.3种氮形态显著提高了2种生态型东南景天地上部和根系的镉积累量,对超积累生态型东南景天,无论在何种镉水平下,(NH4)2SO4处理效果明显好于Ca(NO3)2或NH4NO3处理.本研究结果表明不同氮形态对东南景天Cd积累的促进顺序为:NH4+-N>NO3--N,因此从植物修复角度考虑,在Cd污染土壤中施用适量的(NH4)2SO4提高超积累植物东南景天的生物量和地上部镉积累量具有重要的应用价值.

The effects of nitrogen form on plant growth and cadmium （Cd） accumulation in two ecotypes Sedum alfredii Hance were investigated using hydroponic culture. The results show that biomass （dry matter） of shoots and chlorophyll a, b content of hyperaccumulating ecotype （HE） increased markedly when plants were supplied with （NH4）2SO4, Ca（NO3）2 and NH4NO3, but the increase was greater with the treatment of （NH4）2SO4 under either low （10 μmol. L^-1） or high Cd （100 μmol. L^-1） level. Cadmium concentrations in the shoots of both ecotypes Sedum alfredii Hance were not significantly affected by the treatments of （NH4）2 SO4, Ca（NO3 ）2 and NH4 NO3, whereas the root Cd concentrations increased to a certain extent. Cadmium amount accumulated in the shoot and root of both ecotypes of Sedum alfredii Hance increased significantly when plants were supplied with different nitrogen form, as for hyperaccumulating ecotype treated with （NH4）2SO4, cadmium accumulation increased more than those treated with Ca（NOs ）z and NH4 NOs. Results above indicated that NH4^＋-N has greater ability to promote Cd accumulation in Sedum alfredii Hance than NO3ˉ-N, and the application of （NH4）2SO4 may be useful approach to enhance the Cd accumulation in hyperaccumulating ecotype Sedum alfredii Hanee for phytoremediation of the Cd-contaminated soil.