"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.
2019.
Plant Physiology and
Biochemistry
135: 194-205.
Note:
Rapeseed oil is called
canola oil in the US,
and was formerly called
Canadian Oil, low acid.
CONCLUSIONS:
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
controlled-environment
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:
(1)
CURRENT CLIMATE (CC)
With day/night temperatures
maintained at 21/14 °C,
CO2 at 400 ppm
O3 at current ambient levels,
(2)
CURRENT CLIMATE + CO3 ozone
CC (1) plus O3 concentration,
at 180 µg m-3 higher,
(3)
FUTURE CLIMATE (FC)
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
(4)
FUTURE CLIMATE + CO3 ozone
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
mixed-culture.
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
mixed-culture,
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.