Vegetative growth

The assimilation starts at GSI=1 for annuals and perennials calculated by any of the equations (5.6), (5.8)  or (5.9). The assimilated carbon, C_Atm→a, is moved to a temporary carbon storage pool, C_a. From this pool the assimilates are allocated to the roots, leaves and stem by:

                                                                                              (5.37)

                                                                                             (5.38)

                                                                  (5.39)

The allocation fraction to the roots, f_root, may be influenced by the shoot mass of plant, f(M), the nitrogen to carbon ratio in the leaf, f(CN_leaf ), and of the water stress, f(E_ta /E_tp ), in three different ways (see switch Root alloc combination):

•      Average response:
       (5.40)

•      Maximum response:
        (5.41)

•      Multiplicative response:
               (5.42)

The mass response, f(M), the leaf nitrogen to carbon ratio response, f(CN_leaf ) and the water stress response, f(E_ta /E_tp ), can in turn be calculated in three different ways respectively.

The mass response, f(M), can be calculated in the following three ways (see switch Root allocation mass):

•      Exponential function:
                              (5.43)

•      Independent:
                                              (5.44)

•      Linear function:
                                  (5.45)

where r_Mc1, r_Mc2 and r_Mc3 are parameters and M is the carbon content in the leaves and the stem. See viewing functions Allocation of carbon – exponential function and Allocation of carbon – linear function.

The nitrogen response, f(CN_leaf ), can be calculated in the following three ways (see switch Root allocation N leaf):

•      Exponential function:
                    (5.46)

•      Independent:
                                         (5.47)

•      Linear function:
                       (5.48)

 

where r_CNc1, r_CNc2 and r_CNc3 are parameters and CN_leaf is the leaf nitrogen response (see eq. (5.12)). See viewing functions Allocation of carbon – exponential function and Allocation of carbon – linear function.

The water stress response, f(E_ta /E_tp ), can be calculated in the following three ways (see switch Root allocation water):

•      Exponential function:
                   (5.49)

•      Independent:
                                        (5.50)

•      Linear function:
                   (5.51)

 

where r_Wc1, r_Wc2, and r_Wc3 are parameters, E_ta is the actual transpiration and E_tp is the potential transpiration. See viewing functions Allocation of carbon – exponential function and Allocation of carbon – linear function.

The allocation fraction to the leaves, f_leaf, can be calculated in four different ways (see switch Leaf allocation shoot):

•      Exponential:
                                      (5.52)

•      Independent:
                                                   (5.53)

•      Linear function:
                                        (5.54)

•      ExpFunc of Stem/Leaf:

                                                                    (5.55)

 

where l_c1, l_c2, and l_c3 are parameters and M stands for mass and is the carbon content in the stem and the leaves. See viewing functions Allocation of carbon – exponential function and Allocation of carbon – linear function.