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Saturday, May 11, 2019

Kaciene et al. (2019) -- Positive Influence of elevated CO2 and ozone on plant growth

"O3 pollution 
in a future climate 
increases the competition 
between summer rape 
and wild mustard. "

Kaciene, G., Miskelyte, D., 
AbdElgawad, H., Beemster, G., 
Asard, H., Diksaityte, A.,
Zaltauskaite, J., Sujetoviene, G., 
Januskaitiene, I. and Juknys, R.


Plant Physiology and 
135: 194-205.

Rapeseed oil is called 
canola oil in the US, 
and was formerly called 
Canadian Oil, low acid.

The growth 
of oilseed rape,
used for canola oil
(there is no "canola" plant)
will be enhanced 
as temperatures warm,
and atmospheric 
CO2 concentrations 
rise in the future, 
regardless of 
ozone (O3) levels,
and oilseed rape
will become more 
competitive against 
the invasive wild 
mustard weed too !

Kaciene et al. (2019) examined
the impact of elevated CO2, 
elevated temperature, and 
elevated ozone (O3), 
on the growth of oilseed rape 
(Brassica napus), 
an important 
agricultural crop, 
and wild mustard 
(Sinapis arvensis), 
a weed often found 
growing in competition 
with oilseed rape.

Seedlings of the 
two species 
were grown in a
at Vytautas Magnus 
University, Lithuania, 
under the four conditions 
over a three week period.

The authors say their results
"revealed that elevated CO2 
and temperature stimulated 
rape's growth: biomass of root 
and shoot, leaf area as well as 
accumulation of soluble sugars 
significantly increased." 

Oilseed rape biomass 
was reduced by 
weed competition 
from wild mustard in the 
FC and FC+O3 treatments.

But the authors report that 
"the competitiveness of rape 
increases more than that 
of the wild mustard"
(with elevated CO2 & temperature)
indicating this important 
agricultural crop will have 
a greater competitive advantage 
over wild mustard in the future"

Cause of competiveness increase: 
Higher CO2 and temperature
led to "better anti-oxidative 
protection, particularly elevated 
total anti-oxidative capacity 
and activities of peroxidase 
and ascorbate peroxidase."

The four growing conditions:

With day/night temperatures 
maintained at 21/14 °C, 
CO2 at 400 ppm
O3 at current ambient levels, 

CC (1) plus O3 concentration,
at 180 µg m-3 higher, 

Higher temperature 
CO2 doubled
O3 normal (ambient)
Temperatures maintained 
at day/night values 
of 25/18 °C, 
CO2 elevated to 800 ppm and  
O3 at ambient levels

FC (3) plus O3 concentration,
at 180 µg m-3 higher.

Species grown in each of  
these four treatments included 
monoculture oilseed rape, 
monoculture wild mustard, 
and a mixed-culture of 
8 wild mustard and 
16 oilseed rape seedlings.

Elevated CO2 and 
elevated temperature 
increased the shoot 
and root biomass 
of oilseed rape 
in both mono- and 

Elevated O3 had 
no significant impact 
on those parameters. 

In contrast, 
for monoculture 
wild mustard (a weed),
shoot biomass 
was only slightly augmented 
in the FC treatment 
(relative to CC) 
and root biomass was 
significantly reduced. 

Elevated O3 had both a 
negative and positive 
effect on monoculture 
wild mustard (weed)
shoot and root biomass 
(negative when 
comparing +O3 with CC 
and positive when 
comparing FC+O3 with FC). 

When grown in 
wild mustard (weed) 
root and shoot biomass 
under the CC+O3, FC
and FC+O3 treatments 
were all lower than that 
observed under control 
CC treatment conditions.