Although recent studies show that the iron oxides do not enter or accumulate in plants, they may preclude the transport of water and nutrients in the plants through/as a consequence of their aggregation on the surface of the roots. The feasibility of using iron oxide nanoparticles to modify the availability of trace elements (TEs) to Helianthus annuus in the soil as well as their interference with the plant response during an imposed water deficiency stress were studied in a pot experiment. Plants were grown in a compost pre-amended contaminated soil with and without nano-maghemite (NM) and later exposed to drought. The nano-amendment promoted the growth of H. annuus (higher (25 %) dry weight than in the same soil without NM), mainly due to the insolubilisation of pore water Zn in the soil and the consequent reduction of its availability to the plants. During the water stress, NM did not cause an increase in the accumulation of proline or total amino acids in the plants, which are normally used as drought stress indicators, compared to the control plants without NM. In conclusion, NM could be useful soil amendments during phytoremediation procedures, since it can immobilise TEs in the soil without disrupting the plant water balance.

Domingo Martínez-Fernández is grateful for the financial support from the European project Postdok ČZU (ESF/MŠMT CZ.1.07/2.3.00/30.0040). This work was partially co-funded by the Spanish Ministry of Economy and Competitiveness (MINECO) and the EU through FEDER funds (CTM2013-48697-C2-1-R), the Czech Science Foundation (GAČR 503/11/0840) and the Internal Grant Agency of Czech University of Life Sciences Prague (CIGA 20154202).

Peer reviewed