Photosynthesis in field conditionss

Pertti Hari

Role of photosynthesis

Dominating source of raw material

Source of energy

Photosynthesis

Light reactions capture of light energy formation of ATP and NADPH

Dark reactions capture of CO2

synthesis of sugar using ATP and NADPH

Chamber Measurements

Chamber is closed for measurements

Mass balance equation for determination of the flux

d(Vc Cc )

dtg qCc qCr

Chamber in action

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Models For Gas Exchange

p(t, x) f (I(t, x),T (t, x), a, b)

p is gas exchange

t timex space coordinatesI light intensityT temperature

a and b parameters

Measuring precission

Can be measured

Compare measurements of the some flux

Chamber measurements for CO2 exchange

During one closure several measurements of CO2 exchange

Comparision of Measurements of CO2 exchange during 10 s at SMEAR I

Precission can be determined as residual of the regression

CO

2 exc

hang

e du

ring

10

s st

arti

ng 3

0 s

afte

r cl

osur

e

CO2 exchange during 10 s starting 20 s after closure

Measured and Modelled CO2 exchange at SMEAR I 1999

Time, rel units Time, rel units

CO

2 exc

hang

eC

O2 e

xcha

nge

Comparision of measured and modelled CO2 exchange summer

1999

Measured CO2 exchange

Modelled CO2 exchange