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Crop responses to climate change

John R PorterFaculty of Life Sciences

University of Copenhagen Denmark

(jrp@life.ku.dk)

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Issues

Climate variability and crop growth:continuous and threshold responses

Crop quality and climate change

Conclusions

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CO2 and European Wheat Yields

Ewert et al. 2004

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Changes in temperature extremes

IPCC 2001

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2003 in Europe

Schar et al, 2004

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Wheat: critical temperatures

Ferris et al., 1998

<Udfyld sidefod-oplysninger her> Wollenweber & Porter 2002

Experimental analysis

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Changes in mean yield, % Changes in yield CV, %

Modelling analysis

Porter et al. 2006

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Denmark: anthesis temperatures

Tmax (oC) June 15-30: 1966-2005

0

5

10

15

20

25

30

35

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IPCC: 2100

1

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Quality

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Amount of protein

6

8

10

12

14

16

Grainproteincontent (%)

CookiesCakesPastries

Japanese noodlesFlat breadsChinese noodlesCrackers

Leavened breadPastaGluten and starch extraction

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NAO and wheat grain quality

Kettlewell et al 1999

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Changes in temperature extremes

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Yield and grain protein CV (%)

  Yield Grain Protein

Baseline 11.1 11.0

Mean T +2oC 10.9 9.7

Mean T +4oC 9.8 8.5

More variable T 14.0 12.5

Longer dry periods 17.6 19.1

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Conclusions

CO2 signal relatively weak for crop yields in Europe

Level and distribution of temperature and rainfall are more important

Critical thresholds need identification

Modelling and experimental studies needed

Quantity and quality

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