Journal of Plant Physiology 182 (2015) 1–12 Contents lists available at ScienceDirect Journal of Plant Physiology journal h om epage: www.elsevier.com/locate/jplph Physiology Salt sensitivity in chickpea: Growth, photosynthesis, seed yield components and tissue ion regulation in contrasting genotypes Hammad Aziz Khan a,b , Kadambot H.M. Siddique b , Rushna Munir a,b , Timothy David Colmer a,b,∗ a School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia b UWA Institute of Agriculture, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia a r t i c l e i n f o Article history: Received 21 March 2015 Received in revised form 30 April 2015 Accepted 13 May 2015 Available online 19 May 2015 Keywords: Chickpea (Cicer arietinum L.) Salt stress Ion exclusion and tissue tolerance Photosynthesis Photosystem II Vegetative/reproductive phases a b s t r a c t Chickpea is a relatively salt sensitive species but shows genotypic variation for salt tolerance, measured as grain yield per plant in mild-to-moderately saline soil. This experiment was designed to evaluate some physiological responses to salinity in three contrasting genotypes. One tolerant (Genesis836), one mod- erately tolerant (JG11) and one sensitive (Rupali) genotype were grown for 108 d in non-saline nutrient solution (controls) and two levels of salinity treatment (30 and 60 mM NaCl). No plants survived to matu- rity in the 60 mM NaCl treatment; however, Genesis836 survived longer (87 d) than JG11 (67 d) while Rupali died after 27 d; only Genesis836 flowered, but no pods were filled. At 30 mM NaCl, Genesis836 produced a few filled pods, whereas JG11 and Rupali did not. Genotypic differences in plant dry mass at the vegetative stage were evident only at 60 mM NaCl, while at maturity differences were evident at 30 mM NaCl. Photosynthesis was maintained to different degrees by the three genotypes (e.g. at 30 mM NaCl, 35–81% of controls; highest in Genesis836); photosynthesis was restricted predominately due to non-stomatal limitations as the intercellular CO 2 concentration was only modestly affected (94–99% of controls). Photosystem II damage was evident in the less tolerant genotypes (e.g. at 30 mM NaCl, actual quantum efficiency of photosystem II values were 63–96% of controls). Across treatments, shoot dry mass was negatively correlated with both Na + and Cl - shoot concentrations. However, the sensitive genotype (Rupali) had equal or lower concentrations of these ions in green leaves, stems or roots compared to toler- ant genotypes (JG11 and Genesis836); ion ‘exclusion’ does not explain variation for salt tolerance among these three chickpea genotypes. The large difference between Rupali (sensitive) and Genesis836 (toler- ant) in the salt-induced reduction in net photosynthesis via non-stomatal limitations and the assessed damage to photosystem II, but with similar leaf ion concentrations, provides evidence that variation in ‘tissue tolerance’ of Na + and/or Cl - in leaves contributes to the differential salt tolerance of these chickpea genotypes. © 2015 Elsevier GmbH. All rights reserved. Introduction Chickpea (Cicer arietinum L.) is an important cool-season pulse crop particularly in the Indian subcontinent and some other countries. Salinity is a major environmental stress limiting crop productivity in arid and semi-arid regions worldwide which is where chickpea is widely grown (Ryan, 1997). Chickpea is a salt sensitive species with an estimated worldwide yield loss of 8–10% due to salinity and complete crop failure can occur in the ∗ Corresponding author at: School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Crawley 6009, WA, Australia. Tel.: +61 8 6488 1993; fax: +61 8 6488 1108. E-mail address: timothy.colmer@uwa.edu.au (T.D. Colmer). worst-affected soils (Flowers et al., 2010). Salinity impairs shoot growth of chickpea while reproductive processes are considered even more sensitive (Lauter and Munns, 1986; Vadez et al., 2012). Nonetheless, the causes of salt sensitivity in chickpea at different growth stages are not clear (Flowers et al., 2010). Considerable variation in salt sensitivity/tolerance in chickpea was observed in salinized soils in pot experiments with plants grown to maturity (Turner et al., 2013; Vadez et al., 2007); how- ever, there is need to understand salt sensitivity of chickpea as well as the tolerance mechanisms. Salt stress results in high accu- mulation of ions (mainly Na + and Cl - ) in different tissues which impairs cellular functioning and restricts plant growth and ulti- mately yield is reduced (Munns, 2002). Growth reductions in chickpea in saline conditions have been associated with accumula- tion of high Na + and/or Cl - in shoots (Flowers et al., 2010); however, http://dx.doi.org/10.1016/j.jplph.2015.05.002 0176-1617/© 2015 Elsevier GmbH. All rights reserved.