TITLE:
Monitoring the Short-Term Response to Salt Exposure of Two Genetically Distinct Phragmites australis Clones with Different Salinity Tolerance Levels
AUTHORS:
Luciana Achenbach, Hans Brix
KEYWORDS:
Osmotic Stress; Salt Stress Response; Photosynthesis; Common Reed
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.5 No.8,
March
26,
2014
ABSTRACT:
Aims: Two genetically distinct clones of Phragmites
australis were used to investigate
the immediate response induced by
osmotic stress. The study aimed at elucidating if the response
time, the inhibition rate and the recovery from salinity stress vary between
these two genotypes. The experimental work was conducted at the laboratory of
the Institute of Bioscience, Aarhus University, Denmark. Methods: The
light-saturated photosynthetic rate (Pmax),
stomata conductance (gs)
and transpiration rate (E) were
measured over different periods of salt exposure (15, 70 and 240 minutes) and
at different salt concentrations (20 and 40 parts per thousand salinity). Important
findings: The osmotic stress induced stomata closure and reduction of Pmax and E for both clones. The clone-specific responses as measured through
physiological parameters were negatively correlated with exposure time
and salt concentration. During the 4-hour exposure at 20 ppt, the two clones
were inhibited at different rates. The salt-sensitive Land-type showed an
immediate reduction
of Pmax, gs and E. No recovery was observed after removing the salt solution. At
the same salt concentration, the reduction of Pmax gs and E of the Greeny-type was lower
and immediate recovery
was observed when the root zone was rinsed. Both clones were irreversibly
inhibited after 4 hours of exposure to 40 ppt. Recovery was primarily related
to exposure time, as Pmax, gs and E rates of both clones recovered
completely after fresh-water rinsing in the 15-minute experiment. The
Greeny-type also recovered after the 70-minute exposure, but not the Land-type.
We