title: Excreting and non-excreting grasses exhibit different salt resistance strategies.
abstract: The combination of traits that makes a plant successful under saline conditions varies with the type of plant and its interaction with the environmental conditions. Knowledge about the contribution of these traits towards salt resistance in grasses has great potential for improving the salt resistance of conventional crops. We attempted to identify differential adaptive response patterns of salt-excreting versus non-excreting grasses. More specifically, we studied the growth, osmotic, ionic and nutrient (carbon/nitrogen) relations of two salt-excreting (Aeluropus lagopoides and Sporobolus tremulus) and two non-excreting (Paspalum paspalodes and Paspalidium geminatum) perennial C4 grasses under non-saline and saline (0, 200 and 400 mM NaCl) conditions. Growth and relative growth rate decreased under saline conditions in the order P. geminatum > S. tremulus = A. lagopoides > P. paspalodes. The root-to-shoot biomass allocation was unaffected in salt-excreting grasses, increased in P. paspalodes but decreased in P. geminatum. Salt-excreting grasses had a higher shoot/root Na(+) ratio than non-excreting grasses. K(+), Ca(2+) and Mg(2+) homoeostasis remained undisturbed among test grasses possibly through improved ion selectivity with rising substrate salinity. Salt-excreting grasses increased leaf succulence, decreased ψs and xylem pressure potential, and accumulated proline and glycinebetaine with increasing salinity. Higher salt resistance of P. paspalodes could be attributed to lower Na(+) uptake, higher nitrogen-use efficiency and higher water-use efficiency among the test species. However, P. geminatum was unable to cope with salt-induced physiological drought. More information is required to adequately document the differential strategies of salt resistance in salt-excreting and non-excreting grasses.
authors.affiliation: Institute of Sustainable Halophyte Utilization (ISHU), University of Karachi, Karachi 75270, Pakistan.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Moinuddin
authors.affiliation: Institute of Sustainable Halophyte Utilization (ISHU), University of Karachi, Karachi 75270, Pakistan.
authors.forename: Salman
authors.initials: S
authors.lastname: Gulzar
authors.affiliation: Institute of Sustainable Halophyte Utilization (ISHU), University of Karachi, Karachi 75270, Pakistan.
authors.forename: Muhammad Zaheer
authors.initials: MZ
authors.lastname: Ahmed
authors.affiliation: Institute of Sustainable Halophyte Utilization (ISHU), University of Karachi, Karachi 75270, Pakistan.
authors.forename: Bilquees
authors.initials: B
authors.lastname: Gul
authors.affiliation: Institute of Plant Ecology, Justus-Liebig University Gießen, Gießen D-35392, Germany.
authors.forename: Hans-Werner
authors.initials: HW
authors.lastname: Koyro
authors.affiliation: Shell Professorial Chair of Sustainable Development, Department of International Affairs, College of Arts and Sciences, Qatar University, PO Box 2713, Doha, Qatar ajmal.khan@qu.edu.qa.
authors.forename: Muhammad Ajmal
authors.initials: MA
authors.lastname: Khan
keywords: C–N balance; Na+ flux; compatible solutes; halophytic grasses; ion homoeostasis; nitrogen-use efficiency.