ISSN 10214437, Russian Journal of Plant Physiology, 2010, Vol. 57, No. 6, pp. 887–891. © Pleiades Publishing, Ltd., 2010.
A distribution of species with respect to elevation is
characteristic of salt marshes . Such zonation is
determined to a great extent by each species physio
logical tolerance to abiotic environmental factors .
Among these, light regime has been identified as play
ing an important role in salt marsh zonation, deter
mining germination responses , survivorship ,
and damage to the photosynthetic apparatus . The
radiation intensity and photoperiod experienced by
the plant are affected by factors such as tidal move
ment and vegetation cover and change throughout the
tidal frame. Thus salt marshes are ideal for examining
adaptive responses of plants to light regime.
Four taxa of perennial halophytes belonging to the
cooccur in European salt marshes,
colonizing the whole tidal frame from low to high ele
(Miller) A.J. Scott ssp.
is an intertidal macrophyte that grows in regu
larly flooded and open low marshes ;
This text was submitted by the authors in English.
(Lag.) Castroviejo grows in salt pans at high lev
els in the tidal frame ;
(L.) A.J. Scott
which is normally found in high topographical posi
tions exposed to high vegetation cover [7, 8], and a hybrid
which colonizes and domi
nates a habitat intermediate in elevation between those
usually occupied by its parental species .
We hypothesize that these four closely related taxa
will demonstrate different responses to
light intensity. Thus, this paper aims to quantify and
compare the photosynthetic assimilation of
stomatal responses through a wide interval of radia
, and pigment concentra
tions, under laboratory conditions. The discussion
relates the physiological responses to the distribution
and habitat characteristics of the four taxa.
MATERIALS AND METHODS
Adult plants were collected in Janu
ary 2003 in three salt marsh ecosystems in the Gulf of
Cadiz (SW Iberian Peninsula). Clumps of
(Miller) A.J. Scott and the hybrid
were collected in Odiel marshes
A.J. Scott clumps were collected from Piedras marshes
Photosynthetic Responses to Light Intensity
S. RedondoGómez and E. MateosNaranjo
Departamento de Biología Vegetal y Ecología, Facultad de Biología, Avda, Reina Mercedes s/n, 41012 Sevilla, Spain;
fax: +34954615780; email: email@example.com
Received July 20, 2009
—Salt marshes show a characteristic zonation of species distribution, which is correlated with marsh ele
vation. Radiation intensity and photoperiod change throughout the tidal frame. Photosynthetic response to light
s), was determined in the laboratory for four closely related halophytic taxa of the
(Chenopodiaceae), which inhabit different positions in the tidal frame.
which germinates below vegetation cover and is found at high levels in the tidal frame, had the lowest maximum
net photosynthetic rate and stomata conductance values. The two
subspecies demonstrated intermedi
ate maximum net photosynthetic rates but
reached light saturation point at higher light inten
, found in the lowest elevations of the marshes, spends a significant proportion of its
time submerged and therefore needs to take full advantage of available light.
is exposed to very
high light intensities in open salt pans at high elevations. The hybrid,
S. perennis x fruticosa
, which is currently found
at intermediate elevations with less frequent inundation, had the highest net photosynthetic rate and chlorophyll
content. The ability to cope with high light levels may help to explain one of the environmental parameters, which
affects distribution of four taxa throughout the tidal frame and also raise intriguing questions about the future role
of the hybrid in the successive development of these marsh systems.
Keywords: Sarcocornia fruticosa, Sarcocornia perennis
. perennis, S. perennis x fruticosa, S. perennis
, photosynthesis, pigment concentrations, salt marsh.
—net photosynthetic rate; Chl—chlorophyll;
matal conductance; PPFD—photosynthetic photon flux density.