halophytic plants l.
Skip this Video
Download Presentation
Halophytic Plants

Loading in 2 Seconds...

play fullscreen
1 / 22

Halophytic Plants - PowerPoint PPT Presentation

  • Uploaded on

Halophytic Plants. Biology 561 Barrier Island Ecology. Niceties. 80% of the earth is covered by saline water Very few plants are able to tolerate saline conditions without serious damage Plants that survive in saline environments are termed halophytes (c.f., glycophytes)

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
Download Presentation

PowerPoint Slideshow about 'Halophytic Plants' - libitha

Download Now An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
halophytic plants

Halophytic Plants

Biology 561 Barrier Island Ecology

  • 80% of the earth is covered by saline water
  • Very few plants are able to tolerate saline conditions without serious damage
  • Plants that survive in saline environments are termed halophytes (c.f., glycophytes)
  • Most halophytes prefer saline conditions but can survive in freshwater environments
  • Most halophytes are restricted to

saline environments

what is a halophyte
What is a halophyte?
  • The term “halophyte” has not been precisely defined in the literature:
    • Plants capable of normal growth in saline habitats and also able to thrive on “ordinary” soil (Schimper, 1903).
    • Plant which can tolerate salt concentrations over 0.5% at any stage of life (Stocker, 1928).
    • Plants which grow exclusively on salt soil (Dansereau, 1957).
what is a halophyte4
What is a halophyte?
  • Categories of halophilism:
    • Intolerant Plants grow best at low salinity and exhibit decrease in growth with increase in salinity
    • Facultative Optimal growth at moderate salinity and diminished growth at both low and high salinities
    • Obligate Optimal growth at high or moderate salinity and no growth at low salinity
hypothetical glycophyte halophyte growth in various salinities
Hypothetical Glycophyte/Halophyte Growth in Various Salinities

Facultative Halophyte


Growth 

Obligate Halophyte


Salinity 

halophytism in higher plants
Halophytism in Higher Plants
  • Early plants developed in oceanic (i.e., high salinity) environments
    • Marine algae
    • Phytoplankton
    • Cyanobacteria
  • Land plants seem to have lost the

ability to thrive under high salt

conditions; most land plants are glycophytes

Marine algae (Codium sp.) grow and reproduce in waters with elevated salt content


Nostoc sp.

angiosperm halophyte types
Angiosperm Halophyte Types
  • Marine angiosperms
  • Mangroves
  • Coastal strand
  • Salt marshes
saline soils
Saline Soils
  • Possess large quantities of Na+
  • Na+ adsorption on clay particles reduces Ca++ and Mg++ content of soils
  • Marsh soils are typically:
    • Low in oxygen
    • High in carbon dioxide
    • High in methane
  • Marsh soils are constantly changing due to the ebb and flow of the tides
water potential
Water Potential
  • Water potential is a measure of the free energy (or potential energy) of water in a system relative to the free energy of pure water
  • The water potential symbol is psi, 
  • Unit of measure (pressure) = megapascals (Mpa) (10 Mpa = 1 bar [approx. 1 atmosphere])
  • Pure, free water w= 0 (the highest water potential value)
components of water potential
Components of Water Potential
  • w total water potential
  • m matric potential
  • s osmotic (solute) potential
  • p pressure (turgor) potential
  • g gravitational potential
  • Total water potential (w) = m+s+p+ g
typical glycophyte
Typical Glycophyte

w = m + s + p + g


w = 0 + (-0.2) + 0.5 + 0

w = -0.3


w = m + s + p + g


w = 4.0 + (-0.2) + 0 + (-4.0)

w = -0.2

typical halophyte
Typical Halophyte

w = m + s + p + g


w = 0 + (-4.5) + 1.0 + 0

w = -3.5


w = m + s + p + g


w = 4.0 + (-3.0) + 0 + (-4.0)

w = -3.0

regulation of salt content in shoots
Regulation of Salt Content in Shoots

Leaf surface containing salt gland of Saltcedar (Tamarix ramiosissima)

  • Secretion of salts
    • Salt exported via active

transport mechanism

    • Excretion includes Na+ and Cl- as well as inorganic ions

Two celled salt gland of Spartina

Photograph and schematic diagram of salt gland of Aeluropus litoralis

salt glands in black mangrove avicennia marina
Salt Glands in Black Mangrove (Avicennia marina)


(a) sunken gland on upper epidermis; (b) elevated gland on lower epipermis


Concentrations of secreted salts is typically so high that under dry atmospheric conditions, the salts crystallize

regulation of salt content in shoots17
Regulation of Salt Content in Shoots
  • Salt leaching
    • Not well understood, but results from transport of salts to the near epidermis of leaves; precipitation leaches salts
  • Salt-saturated leaf fall
    • Leaves shed after accumulation of salts
    • Occurs in Hydrocotyle bonariensis and others
responses to increased salts
Responses to Increased Salts
  • Succulence Plant organs are thickened due to increased cellular water content
  • Increased growth Reduces cellular solute concentrations
seed dispersal in halophytes
Seed Dispersal in Halophytes
  • Most seeds of halophytes are buoyant
    • Examples are glasswort (Salicornia sp.), coconut (Cocos nucifera), sea rocket (Cakile sp.), and suaeda (Suaeda maritima)
  • Marine angiosperm seeds are not buoyant
    • Examples are Thalassia and Halophila
germination in halophytes
Germination in Halophytes
  • Germination inhibited by high salt concentrations
  • Chlorides are very toxic to germinating plants
  • Optimum germination is in freshwater
  • Germination response in salt water not necessarily correlated to later growth of a plant species under saline conditions
  • Higher temperatures slow germination in salt water
physiological response in halophytes
Physiological Response in Halophytes
  • Switch from Carbon-3 photosynthesis to CAM (crassulacean acid metabolism)
    • Stomates closed during

the day

    • CO2 fixation during

the night

    • Sugars accumulate in cells
  • Decrease osmotic pressure with organic ions (proteins)