Parvin, S., Uddin, S.,
Tausz-Posch, S.,
Fitzgerald, G.,
Armstrong, R. and
Tausz, M.
2019
Elevated CO2
improves yield
and N2 fixation
but not grain
N concentration
of faba bean
(Vicia faba L.)
subjected to
terminal drought.
Environmental and
Experimental Botany 165: 161-173.
NOTE:
Parvin et al. (2019)
studied the response
of faba bean
(Vicia faba cv. Fiesta)
to a +150 ppm
CO2 enrichment
under well-watered, and
water-stressed conditions.
SUMMARY:
Rising atmospheric CO2
greatly stimulated growth
and yield of faba beans,
especially in regions
prone to water-stress.
CO2-induced enhancements
in plant water-use efficiencies
mean the quality of faba bean
harvest may also improve,
especially in water-stressed
regions.
The positive effects
of elevated CO2
were powerful enough
to fully mitigate
the growth retarding
influences of drought,
in terms of total
plant biomass,
seed yield,
pod number,
seed number
and harvest index,
resulting in levels
not significantly
different than plants
in the control treatment,
of well-watered conditions,
and the ambient CO2 level.
As shown in the chart below:
Under well-watered conditions
elevated CO2 increased
faba bean pod number,
seed number,
total biomass,
and seed yield by
+44%, +40%,
+29% and +59%,
respectively.
Terminal drought
had a negative impact
on plant growth and yield
attributes, but under
such water-stressed
conditions,
elevated CO2
still improved
the pod number,
seed number,
total biomass,
and seed yield by
+ 47%, +40%,
+16% and +24%,
respectively.
The nitrogen (N) response
(content and concentration)
of the faba bean plants
across the different treatments:
Elevated CO2
increased total N content,
under both well-watered,
and water-stressed
conditions, by
+39% and +19%,
respectively.
DETAILS:
Work was conducted at the
Agriculture Victoria Research
Plant Breeding Center in Horsham,
Victoria, Australia in 2016.
Using free-air CO2 enrichment
(FACE) technology, six scientists
exposed faba bean crops
to ambient (400 ppm)
or elevated (550 ppm)
CO2 levels under well-watered
(soil maintained at 80% field capacity)
until the reproductive phase.
Then they induced
terminal drought
in half the crops
in each CO2 treatment
by withholding water
until 30% field capacity
was reached, maintaining
this level of water stress
through harvest.
