Roots growth

Dry weight of roots (living and dead) can be calculated using partitioning factors to roots (see topic Partitioning factors) and total biomass rate (see topic Total biomass rate).

Firstly, an AFGEN table is used for deriving the relative death rate of roots in function of development stage (Fdeadroots, Kg Kg-1 d-1). In the figure below there is the pattern of this relationship for a rice cultivar.

Then the dry weight rate of dead roots can be calculated as:

where Bdeadroots is daily rate of dry weight of dead roots (Kg ha-1 d-1), Blivroots,s is daily state of dry weight of living roots at time step s (Kg ha-1 d-1) and Fdeadroots is the relative death rate of roots in function of development stage (from AFGEN table, Kg Kg-1 d-1).

Then, the total biomass rate of the crop (Btot, Kg ha-1 d-1, see topic Total biomass rate) is multiplied to the partitioning factor of roots (see topic Partitioning factors), for obtaining the dry matter growth rate of roots (Bbelow)

where Bbelow is the dry matter growth rate of roots (Kg ha-1 d-1), Btot is the total biomass rate of the crop (Kg ha-1 d-1) and Proots is partitioning factor of roots (unitless).

Then the dry weight of living roots is calculated:

where Blivroots is daily rate of dry weight of living roots (Kg ha-1 d-1), Bbelow is the dry matter growth rate of roots (Kg ha-1 d-1), Proots is partitioning factor of roots (unitless) and Bdeadroots is daily rate of dry weight of dead roots (Kg ha-1 d-1).

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