Copper Phytoextraction in Tandem with Oilseed Production Using Commercial Cultivars and Mutant Lines of Sunflower

Abstract

Use of sunflower (Helianthus annuus L.) for Cu phytoextraction and oilseed production on Cu-contaminated topsoils was investigated in a field trial at a former wood preservation site. Six commercial cultivars and two mutant lines were cultivated in plots with and without the addition of compost (5% w/w) and dolomitic limestone (0.2% w/w). Total soil Cu ranged from 163 to 1170 mg kg⁻¹. In soil solutions, Cu concentration varied between 0.16– 0.93 mg L⁻¹. The amendment increased soil pH, reduced Cu exposure and promoted sunflower growth. Stem length, shoot and capitulum biomasses, seed yield, and shoot and leaf Cu concentrations were measured. At low total soil Cu, shoot Cu mineralomass was higher in commercial cultivars, i.e., Salut, Energic, and Countri, whereas competition and shading affected morphological traits of mutants. Based on shoot yield (7 Mg DW ha⁻¹) and Cu concentration, the highest removal was 59 g Cu ha⁻¹. At high total soil Cu, shoot Cu mineralomass peaked for mutants (e.g., 52 g Cu ha⁻¹ for Mutant 1 line) and cultivars Energic and Countri. Energic seed yield (3.9 Mg air-DW ha⁻¹) would be sufficient to produce oil. Phenotype traits and shoot Cu removal depended on sunflower types and Cu exposure.

KEY WORDS:

• compost
• field experiment
• Helianthus annuus L.
• liming
• phytoremediation
• soil solution

ACKNOWLEDGMENTS

This work was supported by ADEME, Department of Polluted Soils and Sites, Angers, France (Mrs F. Cadière as supervisor) and the University of Bordeaux 1, Department of International Relationships, through European Commission Erasmus Mundus Lot 6. Special thanks to Jean-Paul Maalouf, Lilian Marchand, Yuliya Vystavna, and Galina Brutcova for their help. Authors are grateful to Dr. Christophe Barnier, Dr. Michel Franceschi, and Dr. Olivier Atteia, Institut EGID University Bordeaux 3, Pessac, France for their help in analysing total organic carbon in the samples of soil pore water.

Notes

^aControl soil (Mench and Bes 2009).

^bBL: background levels; for As, mean of frequent As values for all French soil types; for other elements, median and upper whisker values in French sandy soils (Baize 1997; Baize and Tercé 2002). Bold letters indicate concentrations exceeding (>10%) background levels in French sandy soils.

^aSource: http://meteo.canejan.free.fr/basededonnees.htm.

^apot experiment

^baided phytoextraction using chemical chelators

^cPhytotoxic ranges for most plants (in mg Cu kg⁻¹): 15–30 (MacNicol and Beckett 1985), 25–40 (Chaney 1989), 10–70 (Gupta and Gupta 1998).