Flora - Morphology, Distribution, Functional Ecology of Plants
Combined effect of NaCl-salinity and hypoxia on growth, photosynthesis, water relations and solute accumulation in Phragmites australis plants
Introduction
Common reed, Phragmites australis (Cav.) Trin. ex Steudel (synonymous to P. communis Trin.), is a widespread species in the temperate regions of the word (Den Hartog et al., 1989). It’s typical habitats are fresh and brackish water areas of swamps, riversides, and lakesides. In the coastal Mediterranean region of Tunisia, P. australis is the main emergent plant species occupying shallow marshes and fringes of lagoons. It is often the key-species in wetland ecosystems and propagates in several ways, by seed dispersion and vegetative from vertical and horizontal rhizomes and stolons. P. australis is well adapted to waterlogging due particularly to the physiological tolerance of its rhizome to anoxia (Brändle and Crawford, 1987; Engloner, 2009; Wijte and Gallagher, 1996) and its aeration capabilities (Armstrong and Armstrong, 1990; Armstrong et al., 1999; Brix, 1990; Gries et al., 1990; Weisner, 1988). Variability of water depth may affect the performance of P. australis by constraining oxygen supply to the below-ground parts of the plant (White and Ganf, 2002). However, reed plants have adapted to terrestrial habitats and various ecotypes have evolved with resistance to drought, salinity and low temperature (Engloner, 2009; Gorai et al., 2007; Haslam, 1975; Matoh et al., 1988; Pagter et al., 2005; Wang et al., 1998; Zheng et al., 2000). Among these, salinity is a well-known stressor of P. australis, leading to reduced vigor and success in brackish and salt marshes (Burdick et al., 2001). According to the literature limits of salt tolerance of reed plants vary widely (Gorai et al., 2007; Hellings and Gallagher, 1992; Hootsmans and Wiegman, 1998; Lissner and Schierup, 1997), but differing levels of salt tolerance among ecotypes have been reported, which might be due to high plasticity and/or genetic factors (Brix, 1999; Clevering and Lissner, 1999).
In wetland habitats, several environmental constraints may influence plant growth and physiological attributes. Factors that can vary spatially within wetlands include salinity and hypoxia. Determination of species-specific salt and waterlogging tolerance and the responsible mechanisms will contribute to an understanding of common patterns of colonization and zonation of the plants occurrences and the dynamics in saline environments. The experiments reported here represent a contribution to this approach. The aim of the present research was to investigate, for P. australis seedlings grown under hydroponic conditions, whether combination of hypoxia with increasing osmolality of nutrient solution was related to growth, water relations, leaf gas exchange and solute accumulation. Our primary hypothesis stated that plant growth and solute accumulation were the most important factors related to the specific effects of ions under NaCl-salinity. To test this, we determined dry matter partitioning, relative growth rate and inorganic and organic solute composition of hydroponically grown reed plants. A second hypothesis proposes that leaf gas exchange and plant–water relations are intimately related with plant growth.
Section snippets
Plant material and culture conditions
Seeds of P. australis were collected in November 2003 from a location near Gabès (southeast Tunisia). Seeds were surface sterilized in 0.58% (w/v) sodium hypochlorite solution for 1 min and germinated on filter paper in 90 mm Petri dishes at controlled conditions (Gorai et al., 2006). Seedlings were transferred to 3 L-plastic tanks for hydroponic growth, using aerated Hewitt nutrient solution (Hewitt, 1966), containing macronutrients (mM): MgSO4 (1.5), KH2PO4 (1.6), K2HPO4 (0.4), KNO3 (3), NH4NO3
Growth and chlorotic status
Three-month-old reed plants were grown hydroponically with continuous air bubbling, at which time a 21 days hypoxic treatment (H) was applied by arrest of air bubbling. Shoots were always maintained in air. As shown in Fig. 1, oxygen levels were maintained at about 20% in the aerated solutions while oxygen levels in the hypoxic solutions rapidly decreased to 8% within 1 day and by 2 day had stabilized to about 4%. There was no gradient of oxygen between 5 and 15 cm below the surface.
P. australis
Discussion
Hypoxia and salinity are two key environmental factors (stresses) of estuarine ecosystems. The ability to overcome multiple and simultaneous stresses is of great importance for the plant growth and survival in such environments (Lichtenthaler, 1996). This study evaluated the physiological response of P. australis grown under interactive effects of salinity and hypoxia in nutrient solution.
The reed plants grew optimally under hypoxia control conditions and at moderate salinity in comparison with
Acknowledgements
The authors are grateful to Prof. Rainer Lösch and anonymous referees for their critical reading and revision of the manuscript.
References (68)
- et al.
Phragmites australis: effects of shoot submergence on seedling growth and survival and radial oxygen loss from roots
Aquat. Bot.
(1999) Some important physiological selection criteria for salt tolerance in plants
Flora
(2004)- et al.
Variation in soil salinity associated with expansion of Phragmites australis in salt marshes
Environ. Exp. Bot.
(2001) - et al.
Carbon isotope composition of Phragmites australis in a constructed saline wetland
Aquat. Bot.
(2005) - et al.
Taxonomy, chromosome numbers, clonal diversity and population dynamics of Phragmites australis
Aquat. Bot.
(1999) - et al.
Reed: a common species in decline
Aquat. Bot.
(1989) Structure, growth dynamics and biomass of reed (Phragmites australis) – a review
Flora
(2009)- et al.
Effects of NaCl-salinity on amino acid and carbohydrate contents of Phragmites australis
Aquat. Bot.
(2001) - et al.
Four helophyte species growing under salt stress: their salt of life?
Aquat. Bot.
(1998) Vegetation stress: an introduction to the stress concept in plants
J. Plant Physiol.
(1996)
Effects of salinity on the growth of Phragmites australis
Aquat. Bot.
Effect of climate on salt tolerance of two Phragmites australis populations. I. Growth, inorganic solutes, nitrogen relations and osmoregulation
Aquat. Bot.
Effect of climate on salt tolerance of two Phragmites australis population. II. Diurnal CO2 exchange and transpiration
Aquat. Bot.
Submergence-induced damage of photosynthetic apparatus in Phragmites australis
Aquat. Bot.
Tolerance and physiological responses of Phragmites australis to water deficit
Aquat. Bot.
Osmotic and ionic effects of NaCl and Na2SO4 salinity on Phragmites australis
Aquat. Bot.
Factors affecting the internal oxygen supply of Phragmites australis in situ
Aquat. Bot.
A comparison of the morphology, gas space anatomy and potential for internal aeration in Phragmites australis under variable and static water regimes
Aquat. Bot.
Light-enhanced convective throughflow increases oxygenation in rhizomes and rhizosphere of Phragmites australis (Cav.) Trin. ex Steud.
New Phytol.
Crop production in artificial solutions and in soils with special reference to factors affecting yields and absorption of inorganic nutrient
Soil Sci.
Responses of some newly evolved salt-tolerant genotypes of spring wheat to salt stress. 2). Water relations and gas exchange
Acta Bot. Neerl
Rapid determination of free proline for water-stress studies
Plant Physiol.
Genetically engineered plants resistant to soil dry and salt stress: how to interpret osmotic relations?
Plant Physiol.
Stomatal behavior and water relations of waterlogged tomato plants
Plant Physiol.
Rhizome anoxia tolerance and habitat specialization in wetland plants
Osmoregulation in halophytic higher plants: a comparative study of soluble carbohydrates, polyols, betaines and free proline
Plant Cell Environ.
Gas exchange through dead culms of reed, Phragmites australis
Aquat. Bot.
Genetic diversity, ecophysiology and growth dynamics of reed (Phragmites australis)
Aquat. Bot.
Water stress induces different photosynthesis and electron transport rate regulation in grapevine
Plant Cell Environ.
Effects of drought on photosynthesis in grapevines under field conditions: an evaluation of stomatal and mesophyll limitations
Funct. Plant Biol.
Seed germination characteristics of Phragmites communis: effects of temperature and salinity
Belg. J. Bot.
The effect of sodium chloride salinity on the growth, water status, and ion content of Phragmites communis Trin
Pak. J. Biol. Sci.
Effects of NaCl on flows of N and mineral ions and NO3− reduction rate within whole plants of salt-sensitive bean and salt-tolerant cotton
Plant Physiol.
Mechanisms of salt tolerance in nonhalophytes
Ann. Rev. Plant Physiol.
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