Table 2.
CRootBox parameter values used for the reconstruction of the rice root system of NERICA4 grown under contrasting conditions. P availability comprised three levels: NoP, SubP and PlusP, while water included two levels: field capacity (FC) vs. drying cycles (DP)
| FC | DP | |||||
|---|---|---|---|---|---|---|
| NoP | SubP | PlusP | NoP | SubP | PlusP | |
| Nodal roots | ||||||
| Number of nodals* (–) | 60 | 69 | 100 | 43 | 55 | 69 |
| Nodal diameter* (cm) | 1.080 | 1.075 | 1.350 | 1.045 | 1.055 | 1.250 |
| Emerging coefficient† (d–1) | 12 | 8.5 | 13.5 | 10 | 5 | 12.5 |
| Maximal root length‡ (cm) | 90 | 90 | 90 | 90 | 90 | 90 |
| Initial elongation rate† (cm d–1) | 2 | 2 | 2 | 2 | 2 | 2 |
| Length of basal zone§ (cm) | 1 | 1 | 1 | 1 | 1 | 1 |
| Length of apical zone§ (cm) | 1 | 1 | 1 | 1 | 1 | 1 |
| Insertion angle† (rad) | 0.7 | 0.8 | 0.8 | 0.7 | 0.8 | 0.8 |
| Tropism type§ (–) | 1 | 1 | 1 | 1 | 1 | 1 |
| Tropism strength* (–) | 0.7 | 0.7 | 0.7 | 0.7 | 0.7 | 0.7 |
| Root flexibility§ (cm–1) | 0.2 | 0.2 | 0.2 | 0.2 | 0.2 | 0.2 |
| First-order lateral root distribution (on the nodal roots) | ||||||
| Lateral type transition steepness, s Eqn 7 S2† (cm–1) | 0.3 | 1.5 | 1.5 | 0.3 | 0.3 | 1.5 |
| Lateral type transition depth, z0 Eqn 7 S2† (cm) | –12 | –20 | –20 | –15 | –18 | –15 |
| Inter-branch distance at proximal end of nodal roots* (i.e. only S-types) (cm) | 0.35 | 0.19 | 0.21 | 0.35 | 0.30 | 0.27 |
| Inter-branch distance scaling factor at distal end of nodal roots, ks,∞ Eqn 8 S2† (–) | 1.6 | 1.85 | 2.3 | 1.8 | 1.9 | 1.65 |
| Inter-branch distance transition depth, z0 Eqn 8 S2† (cm) | –13 | –20 | –20 | –25 | –15 | –20 |
| Inter-branch distance slope, s Eqn 8 S2† (cm–1) |
1.5 | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 |
| S-type lateral roots (do not create second-order laterals) | ||||||
| S-type radius* (µm) | 131.3 | 118.8 | 106.3 | 118.8 | 112.5 | 100.0 |
| Maximal root length‡ (cm) | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 |
| Initial elongation rate§ (cm d–1) | 1 | 1 | 1 | 1 | 1 | 1 |
| Tropism type§ (–) | 1 | 1 | 1 | 1 | 1 | 1 |
| Tropism strength§ (–) | 3.5 | 3.5 | 3.5 | 3.5 | 3.5 | 3.5 |
| Root flexibility§ (cm–1) | 1 | 1 | 1 | 1 | 1 | 1 |
| L-type lateral roots (create second-order laterals) | ||||||
| L-type radius* (µm) | 187.5 | 175.0 | 168.8 | 206.3 | 150.0 | 209.4 |
| Maximal root length† (cm) | 6.5 | 4 | 4 | 6.5 | 4 | 4 |
| Initial elongation rate† (cm d–1) | 1.5 | 1 | 1 | 1.5 | 1 | 1.5 |
| Length of basal zone† (cm) | 0.5 | 0.5 | 0.5 | 0.5 | 0.4 | 0.37 |
| Length of apical zone† (cm) | 0.5 | 0.5 | 0.5 | 0.5 | 0.4 | 0.37 |
| Inter-branch distance* † (cm) | 0.7 | 0.7 | 0.6 | 0.5 | 0.4 | 0.37 |
| Insertion angle§ (rad) | 1.2 | 1.2 | 1.2 | 1.2 | 1.2 | 1.2 |
| Tropism type§ (–) | 1 | 1 | 1 | 1 | 1 | 1 |
| Tropism strength§ (–) | 3.5 | 3.5 | 3.5 | 3.5 | 3.5 | 3.5 |
| Root flexibility§ (cm–1) | 0.2 | 0.2 | 0.2 | 0.2 | 0.2 | 0.2 |
| Second-order lateral roots (branching from L-type laterals) | ||||||
| Maximal root length‡ (cm) | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 |
| Initial elongation rate‡ (cm d–1) | 1.5 | 1 | 1 | 1.5 | 1.5 | 1.5 |
| Tropism type§ (–) | 1 | 1 | 1 | 1 | 1 | 1 |
| Tropism strength§ (–) | 1 | 1 | 1 | 1 | 1 | 1 |
| Root flexibility§ (cm–1) | 0.2 | 0.2 | 0.2 | 0.2 | 0.2 | 0.2 |
*Parameters from direct measurements in the laboratory experiment.
†Manually calibrated parameters to fit the measured root mass fractions in each soil section.
‡Parameters set to match the generally observed rice root systems (derived from pictures and/or few measurements).
§Standard parameters from CRootBox.