Shoot Cadmium Accumulation and Photosynthetic Performance of Barley Plants Exposed to High Cadmium Treatments

Abstract

Barley (Hordeum vulgare L., cv. Ribeka) plants grown in sand culture were exposed for 10 days to high cadmium (Cd) treatments in order to study both shoot Cd accumulation and photosynthetic performance. Cadmium inhibited root dry mass and induced changes in biomass allocation pattern without any effect on biomass accumulation at the whole plant level. The maximal shoot Cd concentration—41 ± 8 mg Cd kg⁻¹ DW—without any visual toxicity symptoms on the shoots was found at 28 mg Cd kg⁻¹ sand. Reduced leaf gas exchange, photosynthetic pigments content and electron transport activity but not altered lipid peroxidation status of thylakoids was, however, detected at the highest treatment—42 mg Cd kg⁻¹ sand. The results indicated good tolerance of barley growth and photosynthetic machinery to Cd, but the shoot Cd accumulation achieved even in the artificial conditions was considered insufficient for short-term phytoextraction.

Keywords:

• Barley
• Cadmium
• Chlorophyll a fluorescence
• Leaf gas exchange
• Lipid peroxidation
• Photosynthetic electron transport
• Photosynthetic pigments

Acknowledgments

The authors thank Tech. Eng. Carlos S. Carvalho and Ana P. Ramos for technical assistance, Engs. José M. Semedo and Nuno C. Marques (all from EAN, Oeiras, Portugal) for help with gas-exchange measurements as well as the Dept. Plant Physiology in EAN for the working facilities provided. The authors also thank Prof. J. Vangronsveld (Limburgs University Centrum, Diepenbeek, Belgium) and Dr. P. Kettlewell (Harper Adams Agricultural College, England) for the critical reading of the manuscript and the valuable corrections. The European Scientific Foundation (GPoll Programme) is gratefully acknowledged for providing a grant to A. Vassilev.