README to use the VK- and VKR-model and the biophysically detailed two-sink water and sucrose transport model as described by van den Herik & ten Tusscher (2021)  

1. VK-model
The VK-model can be solved and plotted using the script potato_VK. Standard, paramaters as used for figure 2, 3 and 4 are included, but these can easily be adjusted.

2. VKR-model
The VKR-model can be solved and plotted using the script potato_VKR. Standard, equal sink parameters are included for a source concentration varying between 10 and 2500mM. These global parameters 
can be adjusted to vary sink characteristics. Standard, the script runs a for-loop to vary the source concentration. The equations solved are taken from Bancal & Soltani (2001) as discussed 
in more detail in the article. 

3. Biophysically detailed model
3.1. Model Implementation
Below the scripts needed for the simulations and their respective functions are given:
- potato_main includes options to change loss_mode and timestep, as well as the set of implemented differential equations
- potato_init, defines model architecture and initial conditions
- potato_parameters, defines the used parameters
- potato_unloading, defines sink properties
- potato_transport_phloem_xylem, calculates transport in the phloem and xylem
- potato_loss_retieval, calculates loss, retrieval and removal from phloem and apoplast

3.2. Running the model
Running potato_main as supplied online simulates a two-sink system with the standard potato parameters as decribed in the manuscript and in more detail in van den Herik et al. (2020).
The results from the ODE solver are stored in the t (time) and y(variables) matrices. These can be saved (save('YOURNAME.mat') or exported afterwards.
Standard the model is run multiple times to create the partitioning coefficient figures from figures 2,3,4 in the manuscript. 

3,3. Loss modes, xylem addition, and parameter variation
To include efflux, retrieval or removal we included three options in potato_main:
1 = No-Leakage, 2 = loss-only, 3 = loss-Retrieval, 
by setting 'loss_mode' to 1, 2 or 3 the mode can be changed.

Xylem dynamics can be turned on by changing 'Xyl', with 0 being off, i.e. constant water potential of 0, and with 1 being on.

The sink characteristics can be changed using the structure 'sc', which includes vmax, Km and pathway length.