Cultivar-level crop parameters

This section describes the JSON properties used to configure cultivar-level crop parameters in MONICA.

Cultivar parameters describe characteristics that may differ between cultivars of the same species. They complement, but do not replace, the corresponding species parameters.

JSON conventions

Number means a JSON number and may contain an integer or decimal value.
Integer means a whole-number JSON value.
Stage-dependent arrays must contain one entry for each developmental stage defined by the species parameters.
Organ-dependent matrix rows must contain one entry for every species organ.

Organ IDs in yield components are one-base:

1. root
2. leaf
3. steam or shoot
4. storage organ, such as fruit, grain, or ear

Numeric values may be written directly:
```
"MaxCropHeight": 0.83
```
They may also contain unit metadata:
```
"MaxCropHeight": [0.83, "m"]
```

Stage-dependent arrays may similarly contain unit metadata:

"StageTemperatureSum": [[148, 284, 380, 180, 420, 25], "°C d"]

MONICA reads the numeric value or array but does not validate the unit string or perform unit conversion. Values must already use the units documented below.

General and crop-cycle parameters

Parameter Name	Type	Description	Example
`type`	String	Serialization metadata identifying the object as cultivar parameters	`"type": "CultivarParameters"`
`CultivarName`	String	Identifier or name of the cultivar	`"CultivarName": "winter wheat"`
`Description`	String	Optional textual description of the cultivar	`"Description": ""`
`Perennial`	Boolean	Indicates whether the cultivar is perennial	`"Perennial": false`
`WinterCrop`	Boolean	Indicates whether the cultivar is treated as a winter crop. This flag is used by operations that distinguish winter and non-winter crops.	`"WinterCrop": true`

Photosynthesis and crop-size parameters

Parameter Name	Type	Unit	Description	Example
`MaxAssimilationRate`	Number	kg CO2 ha-1 leaf h-1	Maximum leaf-area-based CO₂ assimilation rate	`"MaxAssimilationRate": 30`
`LightExtinctionCoefficient`	Number		Beer–Lambert light-extinction coefficient used to calculate the fraction of radiation intercepted by the crop canopy	`"LightExtinctionCoefficient": 0.8`
`MaxCropHeight`	Number	m	Maximum potential crop height	`"MaxCropHeight": [0.83,"m"]`
`CropHeightP1`	Number		Slope parameter of the sigmoid crop-height development function	`"CropHeightP1": 6`
`CropHeightP2`	Number		Relative-development position parameter of the sigmoid crop-height function	`"CropHeightP2": 0.5`
`CropSpecificMaxRootingDepth`	Number	m	Cultivar-specific maximum potential rooting depth. The effective rooting depth may also be constrained by soil properties.	`"CropSpecificMaxRootingDepth": 1.3`

Development-stage parameters

The outer index of every stage-dependent array corresponds to a developmental stage.

Parameter Name	Type	Unit	Description	Example
`StageTemperatureSum`	Number (Array)	°C d	Thermal-time requirement thath must be accumulated in each developmental stage before the crop advances to the next stage	`"StageTemperatureSum": [[148,284,380,180,420,25],"°C d"]`
`OptimumTemperature`	Number (Array)	°C	Stage-specific upper temperature used when calculating effective thermal-time accumulation	`"OptimumTemperature": [[30,30,30,30,30,30],"°C"]`
`BaseDaylength`	Number (Array)	h	Stage-specific base or reference day length used with `DaylengthRequirement` to calculate the photoperiod development factor	`"BaseDaylength": [[0,0,7,7,0,0],"h"]`
`DaylengthRequirement`	Number (Array)	h	Stage-specific critical day length. Positive values select the long-day response, negative values select the short-day response, and zero disables photoperiod limitation for that stage.	`"DaylengthRequirement": [[0,20,20,20,0,0],"h"]`
`VernalisationRequirement`	Number (Array)	effective d	Stage-specific effective vernalization-day requirement. A value of zero disables vernalization limitation for that stage.	`"VernalisationRequirement": [0,50,0,0,0,0]`
`DroughtStressThreshold`	Number (Array)		Stage-specific threshold for the ratio of actual to potential transpiration. Below this threshold this threshold, drought responses can affect development, photosynthesis, fertility, and biomass calculation.	`"DroughtStressThreshold": [1,0.9,1,1,0.9,0.8]`
`SpecificLeafArea`	Number (Array)	ha leaf kg-1 leaf DM	Stage-specific leaf area per unit leaf dry-matter biomass	`"SpecificLeafArea": [[0.002,0.0018,0.0017,0.0016,0.0015,0.0015],"ha kg-1"]`
`StageKcFactor`	Number (Array)		Stage-specific crop coefficient used in crop evapotranspiration and interception calculations	`"StageKcFactor": [[0.4,0.7,1.1,1.1,0.8,0.25],"1;0"]`

Biomass allocation and senescence

The outer array index represents the developmental stage. Each inner array uses the species organ order: root, leaf, stem/shoot, and storage organ.

Parameter Name	Type	Unit	Description	Example
`AssimilatePartitioningCoeff`	Number (Array of Arrays)	fraction	Fraction of available assimilates allocated to each organ during each developmental stage. Fractions should normally sum to `1` in active growth stages.	`"AssimilatePartitioningCoeff": [[0.5,0.5,0,0],[0.2,0.2,0.6,0],[0.13,0.2,0.67,0],[0,0,0.03,0.97],[0,0,0,1],[0,0,0,0]]`
`OrganSenescenceRate`	Number (Array of Arrays)	d-1	Daily senescence rate of each organ during each developmental stage	`"OrganSenescenceRate": [[0,0,0,0],[0,0,0,0],[0,0,0,0],[0,0,0,0],[0,0.05,0,0],[0,0.05,0,0]]`
`ResidueNRatio`	Number		Ratio of residue nitrogen concentration to primary-yield nitrogen concentration	`"ResidueNRatio": 0.5`

Heat-stress parameters

Parameter Name	Type	Unit	Description	Example
`CriticalTemperatureHeatStress`	Number	°C	Temperature threshold above which reproductive heat damage begins	`"CriticalTemperatureHeatStress": [31,"°C"]`
`BeginSensitivePhaseHeatStress`	Number	°C d	Cumulative thermal time at which the heat-sensitive reproductive phase begins	`"BeginSensitivePhaseHeatStress": [620,"°C d"]`
`EndSensitivePhaseHeatStress`	Number	°C d	Cumulative thermal time at which the heat-sensitive reproductive phase ends	`"EndSensitivePhaseHeatStress": [740,"°C d"]`

Frost and winter-survival parameters

Parameter Name	Type	Unit	Description	Example
`LT50cultivar`	Number	°C	Cultivar-specific temperature at which 50% frost mortality is expected	`"LT50cultivar": -24`
`FrostHardening`	Number	°C-1 d-1	Coefficient controlling the daily decrease in LT50 caused by cold acclimation	`"FrostHardening": 0.014`
`FrostDehardening`	Number	°C-1 d-1	Coefficient controlling the daily increase in LT50 caused by deacclimation	`"FrostDehardening": 5.05`
`RespiratoryStress`	Number	°C-1 d-1	Coefficient controlling the increase in L50 caused by respiratory stress under snow cover.	`"RespiratoryStress": 0.54`
`LowTemperatureExposure`	Number	°C-1	Coefficient intended to control additional LT50 changes caused by extreme low-temperature exposure. The corresponding model calculation is currently disabled, so this parameter currently has no effect.	`"LowTemperatureExposure": 0.654`

Irrigation parameters

Parameter Name	Type	Unit	Description	Example
`HeatSumIrrigationStart`	Number	°C d	Accumulated crop thermal time at which automatic irrigation may begin	`"HeatSumIrrigationStart": 461`
`HeatSumIrrigationEnd`	Number	°C d	Accumulated crop thermal time at which automatic irrigation ends	`"HeatSumIrrigationEnd": 1676`

Yield and cutting components

OrganIdsForPrimaryYield, OrganIdsForSecondaryYield, and OrganIdsForCutting contain yield-component objects.

Parameter Name	Type	Description	Example
`OrganIdsForPrimaryYield`	YieldComponent (Array)	Organ fractions included in the primary harvested product	`"OrganIdsForPrimaryYield": [{"organId":4,"type":"YieldComponent","yieldDryMatter":0.86,"yieldPercentage":0.85}]`
`OrganIdsForSecondaryYield`	YieldComponent (Array)	Organ fractions included in the secondary harvested product	`"OrganIdsForSecondaryYield": [{"organId":2,"type":"YieldComponent","yieldDryMatter":0.86,"yieldPercentage":0.85},{"organId":3,"type":"YieldComponent","yieldDryMatter":0.86,"yieldPercentage":0.9}]`
`OrganIdsForCutting`	YieldComponent (Array)	Organ fractions included in the default cutting or mowing yield. An empty array means that no default cutting yield components are configured.	`"OrganIdsForCutting": []`

Each YieldComponent contains:

Parameter Name	Type	Unit	Description	Example
`type`	String		Serialization metadata identifying the object as a yield component	`"type": "YieldComponent"`
`organId`	Integer		Species organ referenced by the component	`"organId": 4`
`yieldPercentage`	Number	fraction	Fraction of the organ biomass included in the harvested or cut yield	`"yieldPercentage": 0.85`
`yieldDryMatter`	Number	kg DM kg-1 FM	Dry-matter fraction used to convert dry-matter yield into fresh-matter yield	`"yieldDryMatter": 0.86`

organId must be between 1 and the number of species organs. yieldPercentage and yieldDryMatter should normally lie in the internal [0,1].

Optional temperature-response parameters

Leaf-expansion response

These parameters apply only when temperature-dependent leaf expansion (__enable_T_response_leaf_expansion__) is enabled in sim.json.

Parameter Name	Type	Unit	Description	Example
`EarlyRefLeafExp`	Number	°C	Reference temperature for the early-stage leaf-expansion temperature response	`"EarlyRefLeafExp": 12`
`RefLeafExp`	Number	°C	Reference temperature for the later-stage leaf-expansion temperature response	`"RefLeafExp": 20`

The species parameter TransitionStageLeafExp determines when MONICA changes from the early-stage response to the later-stage response.

Wang-Engel phenology response

These parameters apply only when the optional Wang-Engel phenological temperature response (__enable_Phenology_WangEngelTemperatureResponse__) is enabled in sim.json.

Parameter Name	Type	Unit	Description	Example
`MinTempDev_WE`	Number	°C	Minimum temperature for phenological development	`"MinTempDev_WE": 0`
`OptTempDev_WE`	Number	°C	Optimum temperature for phenological development	`"OptTempDev_WE": 0`
`MaxTempDev_WE`	Number	°C	Maximum temperature for phenological development	`"MaxTempDev_WE": 0`

Legacy parameters

Parameter Name	Type	Unit	Description	Example
`LatestHarvestDoy`	Integer	day of year	Legacy cultivar-level latest-harvest value. It is currently not consumed by the automatic harvest calculation.	`"LatestHarvestDoy": -1`

Example: `winter-wheat.json`

The following example shows a complete cultivar parameter file for winter wheat.

{
  "CultivarName":"winter wheat",
  "WinterCrop": true,
  "AssimilatePartitioningCoeff":[
    [
      0.5,
      0.5,
      0,
      0
    ],
    [
      0.2,
      0.2,
      0.6,
      0
    ],
    [
      0.13,
      0.2,
      0.67,
      0
    ],
    [
      0,
      0,
      0.03,
      0.97
    ],
    [
      0,
      0,
      0,
      1
    ],
    [
      0,
      0,
      0,
      0
    ]
  ],
  "BaseDaylength":[
    [
      0,
      0,
      7,
      7,
      0,
      0
    ],
    "h"
  ],
  "BeginSensitivePhaseHeatStress":[
    620,
    "°C d"
  ],
  "CriticalTemperatureHeatStress":[
    31,
    "°C"
  ],
  "CropHeightP1":6,
  "CropHeightP2":0.5,
  "CropSpecificMaxRootingDepth":1.3,
  "DaylengthRequirement":[
    [
      0,
      20,
      20,
      20,
      0,
      0
    ],
    "h"
  ],
  "Description":"",
  "DroughtStressThreshold":[
    1,
    0.9,
    1,
    1,
    0.9,
    0.8
  ],
  "EndSensitivePhaseHeatStress":[
    740,
    "°C d"
  ],
  "FrostDehardening":5.05,
  "FrostHardening":0.014,
  "HeatSumIrrigationEnd":1676,
  "HeatSumIrrigationStart":461,
  "LT50cultivar":-24,
  "LatestHarvestDoy":-1,
  "LowTemperatureExposure":0.654,
  "MaxAssimilationRate":30,
  "MaxCropHeight":[
    0.83,
    "m"
  ],
  "OptimumTemperature":[
    [
      30,
      30,
      30,
      30,
      30,
      30
    ],
    "°C"
  ],
  "OrganIdsForCutting":[],
  "OrganIdsForPrimaryYield":[
    {
      "organId":4,
      "type":"YieldComponent",
      "yieldDryMatter":0.86,
      "yieldPercentage":0.85
    }
  ],
  "OrganIdsForSecondaryYield":[
    {
      "organId":2,
      "type":"YieldComponent",
      "yieldDryMatter":0.86,
      "yieldPercentage":0.85
    },
    {
      "organId":3,
      "type":"YieldComponent",
      "yieldDryMatter":0.86,
      "yieldPercentage":0.9
    }
  ],
  "OrganSenescenceRate":[
    [
      0,
      0,
      0,
      0
    ],
    [
      0,
      0,
      0,
      0
    ],
    [
      0,
      0,
      0,
      0
    ],
    [
      0,
      0,
      0,
      0
    ],
    [
      0,
      0.05,
      0,
      0
    ],
    [
      0,
      0.05,
      0,
      0
    ]
  ],
  "Perennial":false,
  "ResidueNRatio":0.5,
  "RespiratoryStress":0.54,
  "SpecificLeafArea":[
    [
      0.002,
      0.0018,
      0.0017,
      0.0016,
      0.0015,
      0.0015
    ],
    "ha kg-1"
  ],
  "StageKcFactor":[
    [
      0.4,
      0.7,
      1.1,
      1.1,
      0.8,
      0.25
    ],
    "1;0"
  ],
  "StageTemperatureSum":[
    [
      148,
      284,
      380,
      180,
      420,
      25
    ],
    "°C d"
  ],
  "VernalisationRequirement":[
    0,
    50,
    0,
    0,
    0,
    0
  ],
  "type":"CultivarParameters"
}