Tolerance of Portulaca grandiflora to Individual and Combined Application of Ni, Pb and Zn N. Mihailovic • G. Andrejic ´ • Z ˇ . Dz ˇeletovic ´ Received: 14 April 2014 / Accepted: 3 November 2014 / Published online: 7 November 2014 Ó Springer Science+Business Media New York 2014 Abstract In the present study, metal accumulation capacity and tolerance of Portulaca grandiflora were investigated. Plants were grown under greenhouse condi- tions in pots on soil amended with Ni, Pb and Zn to the final concentration of 2 mmol kg -1 for each metal. Results show considerable accumulating capacity and translocation of Ni and Zn, as well as significant accumulation of Pb in roots. A slight decrease of biomass with Zn and of chlo- rophyll content with Zn and Ni were observed, as well as an increase of proline content with each of the metals. Combinations of metals revealed mutual interference affecting both the uptake and translocation of the metals and their impact on physiological parameters. Results suggest that Portulaca grandiflora, although not a hyper- accumulator, shows a good tolerance and accumulation capacity for Ni, Pb and Zn, but, for the purposes of remediation, interference of the metals must be taken into account. Keywords Metal accumulation Á Metal combination Á Physiological parameters Á Translocation Products of human activities, such as mine tailings, industrial effluents, sewage sludge, traffic, and power plant ash dumps are increasingly contaminating soils with met- als. In Serbia, for instance, excessive concentrations of metals are frequently found in urban and industrial soils (e.g. up to 436 mg kg -1 of Pb) (Slavkovic et al. 2004). In areas surrounding mines or smelters, like the one in Bor, up to 2,540, 230 and 260 mg kg -1 of Cu, Pb and As, respectively, were reported (Nikolic et al. 2011). One of the potentially least expensive and environmental-friendly method for cleaning such areas is phytoremediation. Investigations of accumulating potentials of various plants suitable for this purpose are currently in progress. Some representatives of the genus Portulaca showed resistance towards various stresses. It had been demon- strated that P. oleracea was tolerant towards moderate drought (Rahdari and Hoseini 2012) and salinity (Yazici et al. 2007; Teixeira and Carvalho 2009). Populations of P. tuberosa and P. oleracea naturally growing on soils pol- luted with industrial effluents demonstrated simultaneous hyperaccumulation of several metals including Cd, Cr and As (Tiwari et al.2008) as well as Cu, Ni, Hg and Pb (Dwivedi et al. 2012). P. grandiflora, a common decorative plant, was investigated to a lesser degree as a potential hyperaccumulator of metals. Cho-Ruk et al. (2006) found P. grandiflora tolerant to Pb-contaminated soils but inferior to other selected local species in Pb accumulating capacity. Along with high accumulating potential, plants suitable for phytoremediation must fulfill other requirements to make the process cost-efficient, such as adaptability to various climate conditions, high biomass yield and toler- ance to various simultaneous stresses. The primary effect of most metals is the impairment of cell membranes (Maksymiec et al. 2006). Decrease of chlorophyll con- centration (as an indicator of disrupted photosynthetic system integrity) and increase of malondialdehyde (MDA) concentration (as an indicator of non-enzymatic lipid per- oxidation) are common findings in stressed plants. Proline accumulation is often stimulated in stressed plants and the increase of this protective factor had been confirmed in N. Mihailovic (&) Á Z ˇ . Dz ˇeletovic ´ Institute for the Application of Nuclear Energy (INEP), University of Belgrade, Banatska 31b, 11080 Zemun, Serbia e-mail: nmihailovic@inep.co.rs; nevena.prole@gmail.com G. Andrejic ´ Institute of Botany and Botanical Garden ‘‘Jevremovac’’, University of Belgrade, Takovska 43, 11000 Belgrade, Serbia 123 Bull Environ Contam Toxicol (2015) 94:103–107 DOI 10.1007/s00128-014-1418-z