Juozapaitiene, G., Diksaityte, A.,
Sujetoviene, G., Aleinikoviene, J.
and Juknys, R.
2019
Above-ground and below-ground
carbon allocation of summer rape
under elevated CO2 and air temperature.
Agricultural and Food Science 28: 1-8.
This experiment shows
future CO2 enhanced
plant growth
will be improved
by a temperature rise
at the same time.
Citing the work of
Long and Drake (1991),
Juozapaitiene et al.
explaining their
beneficial outcome
by noting that
"the optimal temperature
for many C3 plants
may increase by
approximately +5 °C,
as CO2 increases
by 300 ppm,
as was the case
in the current
experiment."
As future atmospheric
CO2 concentrations rise,
so will the optimum
temperature (Topt)
of plant photosynthesis
in summer rape.
And because the CO2-induced rise
in Topt is generally much greater
than predictions of future
temperature rise, summer rape
growth and yield will be enhanced,
not compromised.
The good news results
of the experiment
will disappoint
always gloomy
climate alarmists:
Measurements revealed
a CO2-induced stimulation
of plant photosynthesis
in the ambient temperature
and elevated CO2 (EC)
treatment that was +29% higher
than that observed in the
ambient temperature
and ambient CO2
(CON - control) treatment.
Rather than declining
in the elevated
temperature
and elevated CO2
(ETC) treatment,
the photosynthetic rate
increased even higher,
to a value that
was +75% greater
than that measured
in the CON environment
( see chart below ).
For plant biomass;
total plant dry weight
of Brassica napus
was enhanced by 1.3x times
in the EC treatment, and
by a much larger 2.4x times
in the ETC treatment.
Working with summer rape
(Brassica napus cv. Fenja)
five Lithuanian researchers
exposed seedlings of this
important European crop
to two temperature
and two CO2 treatments
for a period of four weeks
in controlled-environment
chambers at Vytautas Magnus
University, Kaunas, Lithuania.
The experiment conditions:
(1) CON
ambient temperature
(day/night regime of 25/18 °C)
and ambient CO2 (400 ppm),
(2) EC
ambient temperature
and elevated CO2 (800 ppm)
(3) ETC
elevated temperature
(day/night regime of 25/18 °C)
and elevated CO2.
After four weeks
the authors measured
various plant photosynthetic
and growth-related parameters.
Juozapaitiene et al. write
that good results are
"explained by
[an increase in]
optimal temperature
for plant growth
(Long and Drake, 1991;
McMurtrie and Wang, 1993)
and net photosynthesis
(Bernacchi et al., 2006;
Alonso et al., 2009)
under elevated CO2."