Actual Growth

The plant growth factor quantifies the fraction of potential growth achieved on a given day and is calculated:

$\gamma_{reg}=1-max(wstrs,tstrs,nstrs,pstrs)$ 5:3.2.3

where $\gamma_{reg}$ is the plant growth factor (0.0-1.0), $wstrs$ is the water stress for a given day, $tstrs$ is the temperature stress for a given day expressed as a fraction of optimal plant growth, $nstrs$ is the nitrogen stress for a given day, and $pstrs$ is the phosphorus stress for a given day.

The potential biomass predicted with equation 5:2.1.2 is adjusted daily if one of the four plant stress factors is greater than 0.0 using the equation:

$\Delta bio_{act}=\Delta bio*\gamma_{reg}$ 5:3.2.1

where $\Delta bio_{act}$ is the actual increase in total plant biomass on a given day (kg/ha), $\Delta bio$ is the potential increase in total plant biomass on a given day (kg/ha), and $\gamma_{reg}$ is the plant growth factor (0.0-1.0).

The potential leaf area added on a given day is also adjusted daily for plant stress:

$\Delta LAI _{act,i}=\Delta LAI_i*\sqrt{\gamma _{reg}}$ 5:3.2.2

where $\Delta LAI _{act,i}$ is the actual leaf area added on day $i, \Delta LAI_i$ is the potential leaf area added on day $i$ that is calculated with equation 5:2.1.16 or 5:2.1.17, and $\gamma _{reg}$ is the plant growth factor (0.0-1.0).