不同钙镁比处理对三种超富集植物生长及吸收重金属的影响

通过水培实验研究了不同钙镁比(Ca/Mg=0.2、0.5、1.0、2.0、4.0、6.0)对Zn/Cd超富集植物东南景天(Sedum alfredii)、Zn/Cd/Ni超富集植物遏蓝菜(Noccaca caerulescens)和Ni超富集植物庭荠属(Alyssum murale)在20 mg Zn·L~(-1)、18 mg Ni·L~(-1)、10 mg Pb·L~(-1)和0.5 mg Cd·L~(-1)胁迫下生长和吸收重金属的影响。研究结果显示:A.murale具有很强的将Ni从地下部转移至地上部的能力(转移系数TF达5.98~11.19)和较高的地上部Ca/Mg比(2.45~16.74);N.caerulescens对Mg转移能力(TFMg为1.43~3.70)大于Ca(TFCa为0.77~1.38);S.alfredii对Mg的转移能力与Ca相似。N.caerulescens在正常营养液(Ca/Mg=2)条件下获得最好的生长和地上部最大Zn/Cd/Ni含量,增加Ca或Mg的供给都会产生抑制作用;A.murale在高Ca(Ca/Mg=6)供给时获得最大的生物量和Ni含量,增Ca有助于地上部Ni的累积,但增Mg降低了地上部Ni含量;增加Ca的供给会增加S.alfredii地上部和地下部的Zn含量,增加Ca或Mg的供给都会增加S.alfredii地下部Cd的含量,但S.alfredii在Ca/Mg=0.2时获得最大的生物量和最大的Zn和Cd含量。S.alfredii、A.murale和N.caerulescens地上部分别在Ca/Mg比为6、0.2、1.0时获得最大的Pb含量,其他Ca/Mg比对三种超富集植物地上部吸收Pb均没有产生显著影响。Ca/Mg比对超富集植物富集重金属能力的影响因植物种类和元素而异。

Effects of Ca/Mg ratios on growth and heavy metal uptake of three hyperaccumulators

Enhancing biomass and heavy metal uptake of hyperaccumulators would improve soil phytoremediation efficiencies. In this study, we investigated the effects of Ca/Mg ratios(0.2, 0.5, 1.0, 2.0, 4.0, and 6.0) on growth and metal uptake by Sedum alfredii(Zn and Cd hyperaccumulator), Noccaea caerulescens(Zn, Cd and Ni hyperaccumulator) and Alyssum murale(Ni hyperaccumulator) under hydroponic system spiked with 20 mg Zn·L^-1, 18 mg Ni·L^-1, 10 mg Pb·L^-1 and 0.5 mg Cd·L^-1. Results indicated that significant high transfer coefficient of Ca(TF, 5.98~11.19) from roots to shoots and Ca/Mg ratio in shoots(2.45~16.74) were found in A. murale. The TF of Mg(1.43~3.70) was higher than that of Ca(0.77~1.38) for N. caerulescens, while TF of Mg(1.24~1.45) was similar to that of Ca(0.88~1.66) for S. alfredii. For N. caerulescens, the greatest growth and Zn/Cd/Ni accumulation of shoots was obtained in normal nutrient solution(Ca/Mg 2.0), but plant growth and metal accumulation were restrained under increased Ca or Mg supply. For A. murale, the highest biomass and Ni accumulation of shoots was observed at the highest Ca/Mg ratio(Ca/Mg 6.0). Increasing Ca supply promoted but increasing Mg supply decreased Ni accumulation in the shoots. For S. alfredii, Zn accumulation in shoots and roots increased with increasing Ca supply, and Cd concentration in roots increased with Ca or Mg supply, but the best growth and the highest Zn and Cd concentrations in shoots were observed at the lowest Ca/Mg ratio(Ca/Mg 0.2). Our results suggest that the effect of Ca/Mg ratio on hyperaccumulators depends on both plant and metal species.