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Table 2 Summary of sub-ambient CO2 effects on daily canopy gas exchange parameters and water use efficiency (WUE) from December 26 to January 8

From: A whole canopy gas exchange system for the targeted manipulation of grapevine source-sink relations using sub-ambient CO2

  

CO2 exchange (g vine−1 day−1)

Water use (L vine− 1 day− 1)

WUE (g C02 L− 1 H2O)

 

Average [CO2]

Day

Night

Net

Day

Night

Total

 

10 day treatment period

 Ambient

412 ppm

69.0

−3.8

65.2

9.0

0.53

9.5

7.1

 Sub-ambient

235 ppm

33.2

−3.1

30.0

10.1

0.48

10.5

3.0

 Change

 

−52%

− 20%

−54%

+ 12%

− 11%

+ 11%

−58%

4 day treatment period

 Ambient

408 ppm

77.4

−3.0

74.4

9.0

0.50

9.5

7.9

 Sub-ambient

408 ppm

76.6

−2.6

74.0

8.9

0.55

9.5

7.9

 10 days

Treatment

0.003

0.100

0.005

ns

0.086

ns

0.002

 

Day

< 0.001

0.012

< 0.001

< 0.001

< 0.001

< 0.001

< 0.001

 

Treatment x Day

0.008

ns

0.007

ns

0.023

ns

< 0.001

 4 days

Treatment

Ns

ns

ns

ns

ns

ns

ns