Ecological Engineering 102 (2017) 636–640 Contents lists available at ScienceDirect Ecological Engineering jo ur nal home p ag e: www.elsevier.com/locate/ecoleng Short communication Germination of Atriplex halimus seeds under salinity and water stress Mandana Shaygan a,∗ , Thomas Baumgartl a , Sven Arnold b a Centre for Mined Land Rehabilitation, Sustainable Minerals Institute, University of Queensland, Brisbane, Australia b Centre for Water in the Minerals Industry, Sustainable Minerals Institute, University of Queensland, Brisbane, Australia a r t i c l e i n f o Article history: Received 10 December 2015 Received in revised form 17 February 2017 Accepted 18 February 2017 Keywords: Germinability Halophyte Hydrotime model Mean germination time Osmotic potential a b s t r a c t Direct seeding is an effective approach for plant re-establishment and revegetation of post-mining areas. However, germination of seeds is influenced by environmental stressors such as soil water conditions and salinity, eventually affecting revegetation success. In this study, we conducted laboratory experiments to evaluate the effect of water stress and salinity on the germination of Atriplex halimus seeds. We exposed seeds to various solutions of NaCl and Polyethylen Glycol (PEG) ranging from soil saturation (0 MPa) to permanent wilting point (−1.5 MPa). We measured the germinability and mean germination time to quantify seed germination. Based on the measured germination data, we estimated the parameters of the hydrotime model, which is a critical tool to predict timing and success of seed emergence. At an osmotic potential of −1.5 MPa, 31% or 3% of the seeds germinated when exposed to PEG or NaCl solution, respectively. This indicates that Atriplex halimus seeds are highly tolerant to water stress, but less tolerant to salinity stress. The results of this study suggest that direct seeding of Atriplex halimus may be an effective path for revegetation of post-mining landscapes where salinity and water stress are predominant features of the environment. © 2017 Elsevier B.V. All rights reserved. 1. Introduction Land revegetation can occur either through passive regenera- tion (Musselman et al., 2012), the transplanting of seedlings (Bouzid and Papanastasis 1994), or direct seeding (Brofas and Karetsos 2002; Doust et al., 2006; Doust et al., 2008; Millsom 2002). The latter may be an effective and economic path for land revegeta- tion on a large spatial scale (Abbad et al., 2004; Engel and Parrotta 2001), but it is potentially limited by environmental factors such as water availability. In this regard, seed germination is a signifi- cant indicator of revegetation success since it initially drives plant establishment and plant community dynamics (Abbad et al., 2004; Arnold et al., 2014a). Seed germination is influenced by environ- mental stressors such as salinity and periods of water deficit (Abbad et al., 2004; Arnold et al., 2014a; Cavallaro et al., 2014), particularly in arid and semi-arid environments. Under rare and erratic rainfall conditions, seed germination may be successful only once in several years (Breckle 1995). Hence, estimating the time and extent of seed germination under water and salinity stress is an essential integral part of any land rehabilitation planning, which is commonly sup- ∗ Corresponding author. E-mail addresses: m.shaygan@uq.edu.au (M. Shaygan), t.baumgartl@uq.edu.au (T. Baumgartl), s.arnold@uq.edu.au (S. Arnold). ported by numerical modelling (Bradford 2002; Bullied et al., 2012; Cavallaro et al., 2016; Köchy and Tielbörger, 2007). In arid and semi-arid environments, post-mining lands can be revegetated using halophytes (Al-Nasir 2009; Chaudhri et al., 1964; Devi et al., 2008; Keiffer and Ungar 2001; Keiffer and Ungar 2002) that can survive, live and complete their life cycle in high concen- trations of salt (∼200 mM NaCl) (Flowers et al., 1986; Khan and Gul 2006). Particularly Atriplex halimus is considered desirable due to its high fodder quality and being a perennial plant species (Abbad et al., 2004). However, while several authors (Abbad et al., 2004; Bajji et al., 2002; Katembe et al., 1998; Khan and Rizvi 1994; Ungar 1996) reported the tolerance of Atriplex species to high levels of salinity and water stress, literature still lacks of any quantitative informa- tion regarding the effects of osmotic pressure (water stress) and ion toxicity (salinity stress) on the germination of Atriplex halimus seeds. Therefore, the primary aim of this study was to evaluate the germination response of Atriplex halimus seeds to salinity and water stress. Based on a germination study on Acacia harpophylla (Arnold et al., 2014a,b), we hypothesized that, under low to moderate levels of salinity, germination is primarily controlled by the osmotic effect rather than ion toxicity. We also aimed to estimate the parameters of the hydrotime model for Atriplex halimus for the purpose of eval- uating the extent and timing of germination in relation to soil water potential and salinity. http://dx.doi.org/10.1016/j.ecoleng.2017.02.050 0925-8574/© 2017 Elsevier B.V. All rights reserved.