Scientia Horticulturae 203 (2016) 224–230 Contents lists available at ScienceDirect Scientia Horticulturae journal homepage: www.elsevier.com/locate/scihorti Physiological responses of Pistacia vera L. versus Pistacia atlantica Desf. to water stress conditions under arid bioclimate in Tunisia Samouna Ben Hamed a,b,∗ , Elkadri Lefi a,b , Mohamed Chaieb b a Laboratory of plant ecophysiology, Faculty of Sciences of Gafsa, S. A. Zarroug City, Gafsa, Tunisia b U.R Biodiversity and Ecosystems in Arid Environments, Faculty of Sciences, University of Sfax, Sfax, Tunisia a r t i c l e i n f o Article history: Received 17 December 2015 Received in revised form 9 March 2016 Accepted 16 March 2016 Keywords: Arid bioclimate Leaf water potential Leaf gas exchanges Pistachio Total chlorophyll content Water stress a b s t r a c t Water stress represents the major factor that affects the growth and development of plants in the arid and semi-arid areas. To improve crop management, the selection of better yielding species under such condi- tion is a principal strategy. In this study, the responses of two pistachio species were studied after water stress followed by re-watering. Indeed, the leaf water potential, relative water content, total chlorophyll content and leaf gas exchanges were assessed during water stress and re-watering. The results showed that, under water stress, Pistacia atlantica Desf. maintained water status, leaf gas exchanges and total chlorophyll content stable compared to Pistacia vera L., which experienced a great decrease. After rehy- dration, P. atlantica showed fast recovery of stomatal parameters, compared to P. vera, suggesting a good tolerance to water stress. The variation of P. vera and P. atlantica responses to water stress and re-watering suggested the higher adaptation of P. atlantica to water stress compared to P. vera. © 2016 Elsevier B.V. All rights reserved. 1. Introduction Water stress is one of the most important environmental fac- tors limiting plant growth and production, especially in arid and semi-arid areas (Gorai et al., 2015). It is known to induce many physiological changes in plants. It has been reported that water stress often reduces leaf water status through a decline in leaf water potential, relative water content. This effect depends largely on plant species and water stress severity (Rahimi et al., 2010; Rostami and Rahemi, 2013; Aref et al., 2013). Consequently, the leaf water status affects photosynthesis through the limitation of the efficiency of the photosystem II (PSII) activity (Fini et al., 2013). Water stress results in photosynthesis disturbances (Mwanamwenge et al., 1999; Yordanov et al., 2000). The decrease in photosynthetic rate may result from stomatal and biochemical limitations (Wise et al., 1992; Angelopoulos et al., 1996; Flexas and Medrano, 2002; Lawlor and Cornic, 2002; Yordanov et al., 2003). The stomatal limitation of photosynthesis is a primary event (Lefi et al., 2004), which is then followed by the adequate changes of photosynthetic reactions (Zlatev and Yordanov, 2004). Indeed, the plant reacts to water deficit with a rapid closure of stomata to avoid further loss of water through transpiration (Cornic, ∗ Corresponding author at: U.R Biodiversity and Ecosystems in Arid Environments, Faculty of Sciences, University of Sfax, Sfax, Tunisia. E-mail address: benhamed22010@yahoo.fr (S. Ben Hamed). 2000; Lawlor, 1995; De Souza et al., 2013). As a consequence, the input and diffusion of CO 2 into the leaf is limited (Flexas et al., 2006). The biochemical limitations of photosynthesis has been attributed to reduced carboxylation efficiency (Jia and Gray, 2003), reduced ribulose-1,5-bisphosphate (RuBP) regeneration (Tezara and Lawlor, 1995), reduced amount of functional Rubisco, ATP synthase (Tezara et al., 1999; Nogués and Baker, 2000), adenosine triphosphate (ATP) synthesis, or to the inhibited functional activity of PSII. Concomitantly, inhibition or damages in the primary pho- tochemical and biochemical processes may occur (Lawlor, 2002). The factor limiting photosynthesis during water stress can vary according to species (Galmés et al., 2007), the degree of induced stress. Therefore, the ability to maintain photosynthesis under water stress is of major importance in water stress tolerance (Li et al., 2011). Under arid conditions, plants can respond to water stress by morphological and physiological changes with modifications that allow the plant either to avoid the stress or increase its tolerance (Chaieb et al., 1992). These adaptations depend largely on species. Plants have developed various mechanisms to withhold or partially reduce the negative effect of drought (Allakhverdiev and Murata, 2004; Kalaji and Loboda, 2009). Examples include the escape from water stress by fast vegetative growth, dehydration avoidance by maintaining hydration or development of physiological toler- ance to water stress (Levitt, 1980; Kozlowski et al., 1991; Jones, 1992; Larcher, 1995; Valladares et al., 2008; Berger et al., 2010). http://dx.doi.org/10.1016/j.scienta.2016.03.019 0304-4238/© 2016 Elsevier B.V. All rights reserved.