CultivarRateParams

A data structure that stores cultivar-specific vernalisation rate parameters in APSIM Next Generation. These parameters define how vernalisation genes (Vrn1, Vrn2, Vrn3) respond to temperature and photoperiod cues during cereal development, enabling genotype-specific simulation of flowering time.

Overview

The CultivarRateParams class is a parameter container that holds vernalisation-related coefficients for a specific genotype or cultivar. These values quantify the rates and thresholds for vernalisation gene expression under different photothermal conditions, including baseline expression rates, cold-induced upregulation, and photoperiod sensitivity.

This class is not a computational model itself but serves as a data structure populated by the CalcCAMPVrnRates function based on controlled environment final leaf number (FLN) observations. The parameters are then used by the CAMP model to simulate genotype × environment interactions that influence flowering time in cereals such as wheat and barley.

Model Structure

This section describes how this model is positioned within the APSIM framework. It outlines the broader structural and computational components that define its role and interactions in the simulation system.

This model inherits structural and functional behaviour from the following core APSIM components:

Connections to Other Components

This section describes how the model interacts with other components in the APSIM Next Generation framework.
These connections allow the model to exchange information—such as environmental conditions, developmental stage, or physiological responses—with other parts of the simulation system. For a general overview of how model components are connected in APSIM, see the Connections Overview.

This data structure is used by:

Component Model Connection Type Description
CAMP CAMP Used by Main phenology model that uses these parameters to simulate vernalisation.
CalcCAMPVrnRates CalcCAMPVrnRates Populated by Calculates and populates these parameters from FLN data.

Model Variables

This section lists the key variables that describe or control the behaviour of this component. Some variables can be adjusted by the user to modify how the model behaves (configurable), while others are calculated internally and can be viewed as model outputs (reportable). For a general explanation of variable types and how they are used within the APSIM Next Generation framework, see the Model Variables Overview.

Configurable and Reportable Properties

The following parameters represent physiological and regulatory coefficients used to simulate flowering development:

  • BaseDVrnVeg (\(\Delta V_{\text{base, veg}}\)): Baseline rate of vernalisation gene expression (Vrn1) in the vegetative phase at high temperatures (e.g., >20°C).
  • MaxDVrnVeg (\(\Delta V_{\text{max, veg}}\)): Maximum upregulation of Vrn1 under cold conditions (e.g., 0°C).
  • BaseDVrnER (\(\Delta V_{\text{base, ER}}\)): Baseline rate of Vrn1 expression during early reproductive phase without photoperiod upregulation.
  • MaxDVrnER (\(\Delta V_{\text{max, ER}}\)): Maximum rate of Vrn1 expression during early reproductive phase under long photoperiod.
  • PpVrn3FactVeg (\(F_{\text{Pp, Vrn3, veg}}\)): Enhancement factor for Vrn1 expression in vegetative phase due to Vrn3 upregulation under long days.
  • PpVrn3FactER (\(F_{\text{Pp, Vrn3, ER}}\)): Enhancement factor for Vrn1 expression in early reproductive phase due to Vrn3 under long days.
  • MaxVrn2 (\(V_{\text{max, Vrn2}}\)): Maximum Vrn2 expression level under long photoperiods, which must be suppressed before full Vrn1 expression can proceed.
  • MethalationThreshold (\(M_{\text{threshold}}\)): Threshold level of cold-induced Vrn1 expression needed to enable persistent Vrn1 activation (methalation).
  • ColdVrn1Fact (\(C_{\text{Vrn1}}\)): Factor by which cold temperatures increase the rate of Vrn1 expression compared to the baseline.

These parameters are essential for simulating genotype × environment interactions that influence time to floral initiation and flowering in cereal crops.

Property Type Description
BaseDVrnVeg double Baseline Vrn1 expression rate in vegetative phase (>20°C)
MaxDVrnVeg double Max Vrn1 expression rate at 0°C during vegetative phase
BaseDVrnER double Baseline Vrn1 expression rate in early reproductive phase
MaxDVrnER double Max Vrn1 expression rate in early reproductive phase under long day
PpVrn3FactVeg double Relative increase in Vrn1 expression by Vrn3 in vegetative phase
PpVrn3FactER double Relative increase in Vrn1 expression by Vrn3 in early reproductive phase
MaxVrn2 double Maximum expression of Vrn2 in long days
MethalationThreshold double Cold requirement before persistent Vrn1 expression occurs
ColdVrn1Fact double Relative cold-induced increase in Vrn1 expression

Read-Only Reportable Properties

No read-only properties are available for this model.

User Interface

This data structure is not directly user-configurable through the UI. It is populated automatically by the CalcCAMPVrnRates function based on genotype-specific FLN observations and controlled environment data.

Practical Example

No practical example is available for this model.

See Also