Sakai, H., Tokida, T., Usui, Y.,
Nakamura, H. and Hasegawa, T.
2019
Yield responses to elevated
CO2 concentration among
Japanese rice cultivars
released since 1882.
Plant Production Science 22: 352-366.
NOTE:
Increasing atmospheric
CO2 concentrations
"will offer opportunities
to increase crop productivity
because CO2 is a substrate
for photosynthesis and
increases photosynthesis rates
and yields".
They note that
"significant intra-specific
variation in the yield response
to elevated CO2 [has been]
found in major food crops."
Therefore,
"screening for
or breeding elevated
CO2-responsive cultivars
offers an effective way
to adapt crops to
global climate change."
Five Japanese scientists
investigated the impacts
of elevated CO2 on
five key rice cultivars
released in Japan
since 1882.
SUMMARY:
Rising atmospheric CO2
will greatly benefit rice yields
in the future.
The best of the five Japanese
varieties to grow in the future
is Koshihikari or Akidaware,
which both produced about
the same yield values
under elevated CO2.
Under ambient CO2 conditions,
the three most recently released
rice cultivars (Koshihikari,
Akihikari and Akidawara)
were approximately +19%
higher than the two oldest
cultivars (Aikoku and Norin 8).
Under elevated CO2 conditions,
the two-year averaged yields
increased by +19.3%, +30.3%,
+15.9%, +3.4% and +19.0%
for Aikoku, Norin 8,
Koshihikari, Akihikari and
Akidawara, respectively,
The two earliest cultivars
tended to be the most
responsive cultivars
to atmospheric CO2
enrichment in terms
of yield.
Elevated CO2 also stimulated
other growth parameters
across the years and cultivars,
including light-saturated
net photosynthesis (+27.9%),
shoot and root dry weights,
total dry weight
at heading (+12.8%),
total dry weight
at maturity (+15.9%),
total nitrogen uptake
at heading (+4.6%)
and maturity (+9.2%),
spikelet density (+10.6%),
panicle number,
spikelets per panicle,
percentage of
ripened grain
and harvest index.
DETAILS:
The five examined cultivars
(commercial release years in parentheses)
were Aikoku (1882),
Norin 8 (1934),
Koshihikari (1956),
Akihikari (1976) and
Akidawara (2009).
Samples of each cultivar
were grown in the field
in 2010 and 2011
in a free-air CO2
enrichment (FACE)
environment located in
Tsukubanirai City,
Ibaraki Prefecture,
Japan.
The season-long
daytime average
CO2 concentration
in the ambient treatment
was 385 ppm in 2010
and 379 ppm in 2011,
whereas it was 585 ppm
and 560 ppm in the
elevated CO2 treatment,
respectively.
