Growth and survival of Halimione portulacoides stem cuttings in heavy metal contaminated soils L. Andrades-Moreno ⇑ , J. Cambrollé, M.E. Figueroa, E. Mateos-Naranjo Departamento de Biología Vegetal y Ecología, Facultad de Biología, Universidad de Sevilla, Apartado 1095, 41080 Seville, Spain article info Keywords: Halimione portulacoides Photosynthesis Phytoremediation Stem cuttings Wetlands restoration abstract The halophytic shrub Halimione portulacoides demonstrates a high tolerance to heavy metal contamina- tion and a capacity for accumulating metals within its tissues. On the Iberian Peninsula, this species has colonized habitats with high levels of metal pollution. The aim of this study is to analyze the response of H. portulacoides stem cuttings to this pollution. Growth, photosynthesis and metal uptake were examined in H. portulacoides through an experiment in which stem cuttings were replanted in metal-contaminated soil. This condition decreased growth and lowered both photosynthetic rate and stomatal conductance. Reduced photosynthetic performance was largely due to the reduced concentration of photosynthetic pigments. Despite these responses, there was some important evidence suggesting the phytoremediatory potential of Halimione stem cuttings. The results of our study indicate that this salt-marsh shrub may rep- resent a biotool of value in the restoration of polluted areas. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction Planting of cuttings has specific advantages over seed sowing for restoration programmes. Cuttings may theoretically be taken at any time of the year from natural stocks while seeds are only available for relatively short periods and for some species a suffi- cient supply of seeds, and thus seedlings, is not always available (Huiskes, 1979; Woodhouse, 1982; Gomes Neto et al., 2006). Although potentially efficient, this system is limited in practice by the capability of cuttings to develop a well-structured root sys- tem under stressful conditions. The ability to regenerate from stem cuttings should be considered an important characteristic of me- tal-tolerant plants as it can enhance fast and continuous biomass production, which is an ideal property for phytoremediation. In this way, the selection of species capable of rapid establishment from cuttings in highly polluted soils could contribute to the im- proved success of restoration projects in heavy metal-contami- nated areas. Halimione portulacoides (L.) Aellen is a halophytic shrub fre- quently found on sandy and muddy coastlines and salt marshes around the coasts of Europe, North Africa and South–West Asia. It is frequently the physiognomically dominant species on well- drained and upper marshes, and often fringes channels and pools that are flooded at high tide (Chapman, 1950). Several recent stud- ies have demonstrated that H. portulacoides is highly tolerant to elevated concentrations of heavy metals (Almeida et al., 2009; Duarte et al., 2007; Sousa et al., 2008; Cambrollé et al., 2012a,b). Although stem cuttings of H. portulacoides have been shown to regenerate both roots and aerial plant tissues in a sterile distilled water medium, there have been no studies exploring the ability of cuttings of this species to establish in metal polluted soils. The aim of the present study was to evaluate the regeneration potential of stem cuttings of H. portulacoides in the presence of high concen- trations of heavy metals, by analyzing the survival, growth and photosynthetic response following replantation in highly metal- contaminated soils. 2. Materials and methods 2.1. Plant material and soil sample collection Seeds of H. portulacoides were collected in the salt marshes of ‘‘La Mata-Torrevieja’’ (Alicante, SE Spain). This salt marsh area does not present elevated levels of heavy metals. The collected seeds were subsequently germinated in perlite moistened with distilled water and maintained at 25 °C for 30 days. The resulting seedlings 0025-326X/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.marpolbul.2013.08.015 Abbreviations: A, net photosynthetic rate; Chl a, chlorophyll a; Chl b, chlorophyll b; C i , intercellular CO 2 concentration; Cx+c, carotenoids; F 0 , minimal fluorescence level in the dark-adapted state; F m , maximal fluorescence level in the dark-adapted state; F v , variable fluorescence level in the dark-adapted state; F v /F m , maximum quantum efficiency of PSII photochemistry; UPSII, quantum efficiency of PSII; Gs, stomatal conductance; NPQ, non-photochemical quenching; RGR, relative growth rate. ⇑ Corresponding author. Address: Departamento Biología Vegetal y Ecología, Facultad de Biología, Universidad de Sevilla, Av Reina Mercedes s/n, 41012 Seville, Spain. Tel.: +34 95 4554795; fax: +34 95 4615780. E-mail address: andrades@us.es (L. Andrades-Moreno). Marine Pollution Bulletin 75 (2013) 28–32 Contents lists available at ScienceDirect Marine Pollution Bulletin journal homepage: www.elsevier.com/locate/marpolbul