rosenthal - crop fertilization
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David Rosenthal - Crop Fertilization in a CO2 enriched world: is it good to be C3? (presentation from Adaptation session at CCAFS Science Workshop, December 2010)TRANSCRIPT
Crop Fertilization in a CO2
enriched world: is it good to be C3
David M. RosenthalCCAFS Science Workshop, Cancun, Dec 1 and 2, 2010
Outline
• Plant responses to elevated CO2 and other agents of climate change at SoyFACE
• Why is photosynthesis of crop plants in the field stimulated less by CO2 than predicted by theory?
• Some approaches to optimize (adapt) photosynthesis to global change
Recent evidence indicates atmospheric [CO2] is increasing more rapidly than the most aggressive
IPCC AR4 projection .
How does elevated CO2 stimulate photosynthesis that is the basis for the projected increases in yield?
Rubisco is not the most efficient enzyme
Energy conversion in C3 and C4 plants
Zhu et al 2008
SoybeanMaize
SoyFACE Experiment
20 meters
350
550
750
0:00 6.00 12:00 18:00 0.00
Fumigation
On
96% of minute
averages within ±10%
[CO2] (µmol mol-1)
Time (h)
Increased photosynthesis in C3 crops grown at elevated CO2 increases yield
Long, Ainsworth, Leakey, Nosberger, Ort (2006) Science 312, 1918-21
Percent Change in Elevated [CO2]
-40 -20 0 20 40 60 80 100 120
Asat
A'
gs
ci/ca
Vcmax
Jmax
Rubisco
Narea
Sugar
Starch
Leaf #
Plant Height
LAI
SLA
Biomass
Crop Yield
Meta analysis of C3 crops grown at elevated CO2 in FACE experiments
Ainsworth and Long (2005) New Phyt. 165:351=-372
Gleadow et al. (2009) Plant Biol 11:79-82
No CO2 stimulation in Cassava Greehouse Experiment
Cassava an increasingly important crop
July 19, 2010
CassavaFACEcv 60444
July 2, 2010
June 7, 2010
August 9, 2010
April 5, 2010
April 15, 2010
Growth at elevated [CO2] at SoyFACE stimulates cassava photosynthesis
Rosenthal et al. unpublished
pla
nt
Ambient CO2 Elevated CO2
Cassava canopies are larger at elevated CO2
Rosenthal et al. unpublished
Rosenthal et al. unpublished
AmbientElevated
Cassava harvested after only 3.5
months !
Ambient CO2 Elevated CO2 Rosenthal et al. unpublished
Rubisco is down regulated at elevated CO2 in cassava
Cassava leaf Carbon/Nitrogen ratio declines at elevated CO2
Rosenthal et al. unpublished
Growth at elevated [CO2] does not increase leaf or tuber cyanide content at SoyFACE
Miller, Gleadow unpublished
Long, Ainsworth, Leakey, Nosberger, Ort (2006) Science 312, 1918-21
“[CO2] Fertilization” of C3 crop photosynthesis falls short of theory
Why is photosynthesis of crop plants in the field stimulated less by CO2 than
predicted by theory?
400
320
240
160
80
0
400 320 240 160 80 0
Time before present, 103 years
Current value
Years below 280 ppm, 395 000 (96%)
Years below 240 ppm, 280 000 (67%)
Years below 200 ppm, 83 500 (20%)
Various sources ; Luthi et al (2008) NATURE 453: 379-382
Zhu et al. (2007) Plant Physiol 145: 513-526
Tobacco over-expressing SBPase grown at elevated [CO2]
SBP 11WT SBP 30
Over expression of SBPase enhances photosynthesis at elevated [CO2]
Rosenthal et al. unpublished
Over expression of SBPase enhances biomass formation at elevated [CO2]
Rosenthal et al. unpublished
CO2
C HHO
CH2OPO32-
C
COO-
HHO
CH2OPO32-
COO-
PGA
PGA
CH2OPO32-
C
COO-
HHO
PGA
O2
CH2OPO32-
COO-
2-phospho-glycolate
CH2OPO32-
C
C
C
CH2OPO32-
OH
H OH
H
O
Ribulose-1,5-bisphosphate
Non-green
algae
Terrestrial
C3
C4
ProkaryotesMutants
Current C3 crop Rubisco
Increase ?
Decrease ?
There is a trade off between ability of Rubisco to discriminate between CO2 and O2 Rubisco catalytic rate
= -10%
Lowering increases light saturated leaf photosynthesis but lowers light limited photosynthesis
C3 Average
Adding „foreign‟ Rubisco
Species Ac' = CANOPY
PHOTOSYNTH.
(mmol m-2
day-1
)
ε c
(% inc.)
Asat
( mol m-2
s-1
)
Current average C3 crop
(kcc = 2.5, = 92.5)
1040
0%
14.9
Amaranthus edulis (C4)
(kcc = 7.3, = 82)
1250
17%
28.3
Amaranthus edulis/current
(kcc = 7.3/2.5, = 82/92.5)
1360
31%
28.3
(2004) Plant Cell and Environment, 27, 155-165
(UN-IPCC 2001)
2000 2020 2040 2060 2080 210040
60
80
Ozo
ne
–P
art
s P
er
Bil
lio
n o
f A
ir
Rising tropospheric ozone 0.5 – 2.5 % per year
Relationship between Soybean Yield & Ozone
Fishman et al.2010 Atmospheric Environment
Summary• Growth at elevated [CO2] stimulated cassava
photosynthesis.
• Rubisco was down regulated in cassava at elevated [CO2], consistent lower leaf N (no change in cyanide content).
• Fresh and dry tuber biomass significantly increased with [CO2], as did harvest index.
• Cassava responded similarly to other C3 plants treated with elevated [CO2].
• CO2 stimulation of photosynthesis is less than predicted by theory.
- lack of adaptation to rapid increase in [CO2]
- inhibition due to increasing levels of tropospheric O3
- increased rates of respiration in CO2-grown plants
- temperatures above optimum for photosynthesis.
SoyFACE 2010
CassavaFACE collaborators:Becky Slattery (UIUC)Kat Grennan (UIUC)Bec Miller (Monash U)Ros Gleadow (Monash U)Claude Fauquet (ILTAB)
SBPase overexpression collaboratorsChristine Raines (U Exeter)Anna Locke (UIUC)Stephen Long (UIUC)