Interactions between the Hyperaccumulator Noccaea caerulescens and Brassica juncea or Lupinus albus for Phytoextraction

Abstract

Trace-element-contaminated soils cause environmental concern and represent a source of contamination for surrounding areas. Phytoremediation uses plants to diminish the environmental risks associated with this contamination. When the final aim is the extraction of the pollutants, this technique requires the use of plants that are able to accumulate high concentrations of the target elements in their aerial part, while producing high plant biomass. Here, pot experiments were carried out in order to determine the interaction between a hyperaccumulator (Nocaea caerulescens) and a metal excluder (Lupinus albus) or an accumulator (Brassica juncea) species regarding their trace element accumulation/exclusion capacity when sharing the rhizosphere. The plants were grown alone or were cocultivated in soils with different levels of trace element contamination. The Zn concentration in N. caerulescens plants was lower in cocultivation with B. juncea than when they were grown alone, indicating competition between the two species for Zn uptake. Contrastingly, when grown with L. albus, the Zn concentrations in N. caerulescens plants were higher than when grown alone. Therefore, under climatic conditions adequate for N. caerulescens growth, cocultivation with L. albus could favor Zn phytoextraction, while in the case of B. juncea, crop rotation rather than cocultivation is recommended for efficient phytoextraction.