Arena, C. and Vitale, L.
2018
"Chilling-induced
reduction of
reduction of
photosynthesis
is mitigated by
exposure to
elevated CO2
concentration"
Photosynthetica 56: 1259-1267
NOTE:
Multiple research studies
have shown that elevated levels
of atmospheric CO2 can alter
important physiological processes
to help lessen or fully ameliorate
the negative impacts of
high temperature stress
on plants.
Very little research has been
conducted on the ability of
higher levels of CO2 to reduce
the negative impacts
of cold temperature stress.
Arena and Vitale (2018) say
cold temperature stress
"represents a critical
environmental stress
that limits
plant productivity
and distribution
in many regions
of the world."
SUMMARY:
In response to chilling stress,
plants in the elevated CO2 treatment
exhibited higher values of CO2 fixation,
photochemical activity and
Rubisco amount than plants
exposed to ambient CO2.
Arena and Vitale say the reason
for this difference was:
(1)
Under ambient conditions,
the "increase of thermal
dissipation processes
was not adequate
to guarantee the PSII
photoprotection and
the phososynthetic
recovery after chilling,"
but
(2)
"The elevated CO2 concentration
in combination with low temperature
exerted a mitigating effect
on reduction of Rubisco content
induced by chilling,"
which allowed leaves
"to maintain higher
photosynthetic rates
and reduce the adverse effect
of low temperature on
Rubisco oxygenase activity,
upon return to
prechilling conditions."
Arena and Vitale conclude
that their study reveals
"the positive effect
of elevated CO2
in mitigating
chilling stress."
DETAILS:
Chilling adversely impacts
key physiological processes.
Even a small
drop in temperature,
which does not produce
visible damage to a plant,
can "induce up to [a]
50% reduction
of plant productivity"
by altering a plant's
"water uptake, mineral nutrition,
photosynthesis, respiration,
and total metabolism."
Given the large volume
of research that demonstrates
the benefits of elevated levels
of atmospheric CO2
on these processes,
the two Italian researchers
set out to examine
"the role of elevated CO2
concentrations in mitigating
chilling-induced photosynthetic
depression in Beta vulgaris L.,
a winter crop widely cultivated
in the Mediterranean
ago-ecosystems."
Arena and Vitale grew chard
( B. vulgaris cv. Cicla )
in a controlled-environment
at the Department of Biology
of the University of Naples
Federico II, Italy, under
well-watered and fertilized
conditions.
Goups of plants were exposed
to one of four five-hour treatments:
(1)
ambient CO2 (360 ppm)
and ambient temperature (25°C),
(2)
elevated CO2 (700 ppm)
and ambient temperature (25°C),
(3)
ambient CO2 (360 ppm)
and low temperature (4°C),
and
(4)
elevated CO2 (700 ppm)
and low temperature (4°C).
During and following
the short-term treatment,
multiple measurements
were made on key processes
relating to photosynthesis
to determine if elevated CO2
was able to reduce the impacts
of chilling stress.