Kannojiya, S., Singh, S.D.,
Prasad, S., Kumar, S.,
Malav, L.C. and
Kumar, V.
2019
Effect of elevated
temperature and
carbon dioxide
on wheat
( Triticum aestivum )
productivity
with and without
weed interaction.
Indian Journal of
Agricultural Sciences 89:
751-756.
Kannojiya et al. (2019), say:
"many reports
are indicating
that rising
carbon dioxide
concentration and
projected changes
in climate could
favor the growth and
development of
weeds over crops,"
which they say could
"have negative
consequences
for agricultural
productivity."
The six Indian researchers
devised an experiment
to examine the interactive
effects of CO2 and temperature
in the presence or absence
of weeds.
The study was performed at the
ICAR-Indian Agricultural Research
Institute in New Delhi, India.
Wheat plants
(Triticum aestivum, cv. HD 2967)
were sown in the field
in temperature gradient
tunnels that maintained
the air temperature
at either ambient temperature
(Ta),
ambient temperature
plus 1.5°C,
or ambient temperature
plus 3.0°C.
CO2 concentrations
were sustained at either
400 ppm (ambient) or
550 ppm (elevated)
throughout the duration
of the growing season.
Kannojiya et al.
sowed two weeds
(Phalaris minor and
Chenopodium murale)
at the beginning of
the growing season
in half of each
temperature and
CO2 treatment
combination.
The impact of these three
factors (CO2, temperature
and weed presence
or absence) on wheat
grain yield is illustrated
in the figure below.
Rising temperatures
and the presence of weeds
both had a negative impact
on wheat grain yield.
Elevated CO2 had
a positive effect.
In most cases
elevated CO2
offset the
two stresses and
enabled grain yields
that were similar to
or greater than that
observed under
ambient CO2,
ambient temperature
and no weeds present.
As shown in the chart:
Grain yield
of wheat plants
grown under
different
combinations of
atmospheric CO2,
temperature and
weeds or no weeds.
ACO2 = ambient CO2
(400 ppm),
ECO2 = elevated CO2
(550ppm),
Ta = ambient temperature.
The percentages shown
in red text indicate the
improvement of grain yield
due to elevated CO2
at a given temperature
and weed regime.
