title: Effects of salinity and ascorbic acid on growth, water status and antioxidant system in a perennial halophyte.
abstract: Salinity causes oxidative stress in plants by enhancing production of reactive oxygen species, so that an efficient antioxidant system, of which ascorbic acid (AsA) is a key component, is an essential requirement of tolerance. However, antioxidant responses of plants to salinity vary considerably among species. Limonium stocksii is a sub-tropical halophyte found in the coastal marshes from Gujarat (India) to Karachi (Pakistan) but little information exists on its salt resistance. In order to investigate the role of AsA in tolerance, 2-month-old plants were treated with 0 (control), 300 (moderate) and 600 (high) mM NaCl for 30 days with or without exogenous application of AsA (20 mM) or distilled water. Shoot growth of unsprayed plants at moderate salinity was similar to that of controls while at high salinity growth was inhibited substantially. Sap osmolality, AsA concentrations and activities of AsA-dependant antioxidant enzymes increased with increasing salinity. Water spray resulted in some improvement in growth, indicating that the growth promotion by exogenous treatments could partly be attributed to water. However, exogenous application of AsA on plants grown under saline conditions improved growth and AsA dependent antioxidant enzymes more than the water control treatment. Our data show that AsA-dependent antioxidant enzymes play an important role in salinity tolerance of L. stocksii.
authors.affiliation: Institute of Sustainable Halophyte Utilization (ISHU), University of Karachi, Karachi 75270, Pakistan.
authors.forename: Abdul
authors.initials: A
authors.lastname: Hameed
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: Irfan
authors.initials: I
authors.lastname: Aziz
authors.affiliation: Institute of Sustainable Halophyte Utilization (ISHU), University of Karachi, Karachi 75270, Pakistan.
authors.forename: Tabassum
authors.initials: T
authors.lastname: Hussain
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: Centre for Sustainable Development, College of Arts and Sciences, Qatar University, PO Box 2713, Doha, Qatar ajmal.khan@qu.edu.qa.
authors.forename: M Ajmal
authors.initials: MA
authors.lastname: Khan
keywords: Antioxidant; Limonium stocksii; exogenous ascorbic acid application; halophyte; salt tolerance