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Saturday, May 18, 2019

Juozapaitiene et al. (2019) Effects of Elevated CO2 and Temperature on Summer Rape

Juozapaitiene, G., Diksaityte, A., 
Sujetoviene, G., Aleinikoviene, J. 
and Juknys, R. 


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 

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 
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."