Emerging
The Emerging phase in Wheat represents the developmental period from Germination to Emergence. It is influenced by sowing depth, a lag period before coleoptile elongation, and the elongation rate of the shoot.
Overview
The EmergingPhase model simulates the time between the Germination and Emergence stages.
- This phase starts at Germination and ends at Emergence, when the seedling is considered to have emerged from the soil.
- The model uses daily Thermal Time, retrieved from the
[Phenology].ThermalTimefunction. - The Target thermal time to complete this phase is defined as:
\[ \text{Target} = \text{ShootLag} + (\text{SowingDepth} \times \text{ShootRate}) \]
Where:
- ShootLag is a lag when coleoptile starting to elongate (°Cd) with default value of 40.0 °Cd,
- ShootRate is the rate of shoot elongation (°Cd/mm) with default value of 1.5 °Cd/mm,
- SowingDepth is the depth at which the seed is sown (mm), taken from
[Plant].SowingData.Depth.
Deeper sowing results in longer emergence delays due to greater thermal time requirement.
Cultivar-Specific Parameters
| Name | Description | Default Value |
|---|---|---|
| [Phenology].Emerging.ShootLag.FixedValue | Lag before coleoptile starts to elongate (°Cd) | 40.0 |
| [Phenology].Emerging.ShootRate.FixedValue | Rate of shoot elongation (°Cd/mm) | 1.5 |
Practical Example
This table illustrates deeper sowing delays emergence due to higher thermal time requirements.
| Sowing Depth (mm) | ShootLag (°Cd) | ShootRate (°Cd/mm) | Target Thermal Time (°Cd) |
|---|---|---|---|
| 40 | 40.0 | 1.5 | 100.0 |
| 50 | 40.0 | 1.5 | 115.0 |
| 60 | 40.0 | 1.5 | 130.0 |