IPhase

Represents a single developmental phase in the APSIM NG phenology module.
IPhase defines the contract that every phase model (e.g. Sowing → Emergence, Emergence → Floral Initiation) must obey so that the phenology engine can advance crop development in a modular, interchangeable way.

Overview

In APSIM NG, crop development is broken into discrete phases.
Each phase knows when it starts, when it ends, how fast it is progressing, and when it has finished.

Models that implement IPhase plug into the core Phenology model; the latter calls DoTimeStep() in every simulation step (i.e. day) to update development and query FractionComplete to determine when to hand control to the next phase.

Inputs

Name Type Source Purpose
Start string .apsimx file / UI The phenological stage at which this phase begins.
End string .apsimx file / UI The phenological stage at which this phase ends.
PropOfDayToUse ref double Phenology engine Proportion of today that can be used by this phase; set to 0 when the phase finishes.

(Implementations will usually read additional daily meteorological or crop‑state variables, but those are outside the scope of the interface itself.)

Methodology

  1. Progress calculation

Each concrete phase overrides DoTimeStep(ref PropOfDayToUse) to accumulate development using its own algorithm (thermal time, photoperiod, vernalisation, etc.).

When the cumulative progress reaches its target, the method returns a non‑zero value and sets PropOfDayToUse to the unused fraction of the day so the next phase can continue.

  1. Fraction complete

FractionComplete exposes the running total as a value in \[[0,1]\], enabling other models (e.g. Leaf growth) to scale processes smoothly across phase boundaries.

  1. State management
  • ResetPhase() allows a simulation (or a new season) to restart the phase from scratch.
  • IsEmerged lets other models know whether the crop has emerged above the soil surface (i.e. this phase is happening above ground), which is critical for processes such as light interception or grazing.

Events

Events Listened For

No events are listened by this function.

Events Raised To

No events are raised by this function.

Properties

Configurable and Reportable Properties

Property Type Description
Start string Name of the phenological stage that marks the start of this phase.
End string Name of the phenological stage that marks the end of this phase.

Read‑Only Reportable Properties

Property Type Description
FractionComplete double Fractional progress through the phase \(0 \le F \le 1\).
IsEmerged bool True once the crop has emerged from the soil.

User Interface

IPhase implementations can be added as children of a Phenology node in the APSIM NG model tree.
Right‑click Phenology → Add Model… and search for the desired phase (e.g. Germination, Floral Initiation).

Practical Example

No practical example is available for this function.

See Also