Wang, A., Lam, S.K., Hao, X.,
Li, F.Y., Zong, Y., Wang, H.
and Li, P.
2018
Elevated CO2 reduces
the adverse effects
of drought stress on a
high-yielding soybean
(Glycine max (L.) Merr.)
cultivar by
increasing water
use efficiency.
Plant Physiology and
Biochemistry 132: 660-665.
NOTE:
Many researchers have examined
how rising levels of CO2 help offset
the stress of drought that can
devastate crop yields.
Wang et al. (2018)
analyzed soybeans
(Glycine max, cv. Zhonghuang 35)
over two growing seasons
(2013 and 2014).
SUMMARY:
Wang et al. conclude that future
elevated CO2 concentrations
"would benefit soybean production
in the arid regions of northern China"
and elsewhere where drought is
a limiting factor to soybean
production and yield.
The authors report elevated CO2
increased net photosynthesis,
water use efficiency,
the effective
quantum yield
of PSII photochemistry,
soluble sugar content,
aboveground biomass
and seed yield.
Water stress (drought)
reduces these parameters,
except water use efficiency.
Elevated CO2
"enhanced the
resistance to drought
by improving the capacity
of photosynthesis and
water use efficiency
in soybean leaves,"
which benefits further
"alleviated drought-induced
negative effects on
aboveground biomass
and grain yield of this
soybean cultivar."
Elevated CO2
increased the
water use efficiency
of soybean by
approximately
+50% and +150%
under well-watered
and water-stressed
conditions (averaged
across both years).
Elevated CO2 stimulated
both the aboveground
biomass and yield of
soybean by
approximately
+15% and +50%
under well-watered
and water-stressed
conditions.
DETAILS:
The plants were grown
in pots in open-top
chambers at Shanxi
Agricultural University,
Taigu, Shanxi, China.
The two CO2 concentrations
were 400 ppm (ambient)
and 600 ppm (enriched).
Initially, all crops received
adequate water, with the
soil water content maintained
at 60-80% of relative water
content.
Then, 25 days after sowing
(the branching stage),
Wang et al. subjected
half of the plants
to water stress
(soil water content
maintained at 35-45%
of relative water content)
through the end of the
experiment at harvest.
Various measurements
were conducted to evaluate
plant growth and development
with and without water stress
as a function of atmospheric CO2.