Maximum assimilation rate

For the calculation of gross instantaneous assimilation rate, firstly a maximum value for the leaf CO2 assimilation rate has to be assigned. This value is crop specific and dependent on the development stage code. An AFGEN table is then used for deriving this variable. The shape of the leaf CO2 assimilation rate in response to development stage is shown in the figure below:

Then, a reduction factor temperature-dependent is calculated with another AFGEN table, starting from average daily temperature, as shown in the figure below.

Next step the maximum leaf CO2 assimilation rate is multiplied to the reduction factor according to the following equation:

where Amax is maximum leaf CO2 assimilation rate (kg ha-1 h-1), Amaxtot is maximum leaf CO2 assimilation rate without temperature-dependent reduction factor (kg ha-1 h-1) and Tlim is temperature-dependent reduction factor (unitless).

Then the initial light use efficiency (kg ha-1 h-1/J m-2 s-1) is calculated with an AFGEN table. It is assumed, that the initial light use efficiency is always higher than 2.0 [kg ha-1 leaf h-1].

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