Variation of tolerance and accumulation to excess iron in 24 willow clones: Implications for phytoextraction

Abstract

Willows (Salix spp.) are characterized by having large biomass, high tolerance to flooding, and strong metal accumulation ability, exhibiting great promise in the phytoremediation of iron (Fe) from contaminated sites. In this study, the variation of Fe tolerance and accumulation in 24 willow clones was investigated with two levels of Fe(II)-EDTA, 0.025 mM (control) and 2.0 mM (treatment) by hydroponic system for 21 days in a greenhouse. Visual symptoms of Fe toxicity were observed in the leaves and roots of Fe sensitive clones. Clonal comparisons showed a great variation in Fe tolerance, and the high levels of Fe reduced biomass productions of most clones. Tolerance indexes (TIs) varied about five-fold based on shoot dry biomass and about six-fold based on root dry biomass among clones. Clones also exhibited a wide variation in Fe concentrations (mg g^–1 DW), ranged from 0.80 to 3.41 in leaves, from 5.40 to 10.51 in stems, and from 3.25 to 17.10 in roots under Fe treatments among clones. Large differences varied in the transport of Fe from roots to aerial parts among clones. The results highlighted the selection of Salix clones with high resistance to Fe toxicity and high Fe accumulation to improve phytoremediation efficacy.

Keywords:

• Salix spp.
• iron toxicity
• tolerance
• accumulation
• phytoremediation

Acknowledgments

The authors would like to thank Zhang Huaxian for her excellent technical assistance.

Additional information

Funding

This work was funded by the Natural Science Foundation of China (Grant No. 31100513), the Key International Cooperative Project of CN-USA (Grant No. 2010DFB33960), the key project from Zhejiang Science and Technology Bureau (Grant No. 2011C13015), and the Fundamental Research Funds for Central Universities.