Start | Index | Overview • PREV | UP | The phenological development of some crops and in particular the formation of flowers (transition from vegetative to generative phase) is sensitive to daylength or it requires the occurence of a certain period of low temperatures. VernaliasationAndPhotoresponse.java modifies the crop specific effective temperature between emergence and anthesis calculated by the SimComponent WeatherTransformer to be accounted for when calculating the temperature sum (TSUM) in the SimComponent LintulPhenology. The modification takes into account both the crop specific daylength as well as vernalisation requirements as defined in the crop property file.
The crop-specific vernalisation requirement is defined by inputting the maximum days for vernalisation (DayVernalMax) and the upper and lower temperature limits (Thigh and Tlow) necessary for vernalisation. If the daily mean temperature (DAVTEMP) is between Thigh and Tlow, the day is fully considered as a vernalisation day (VernalDay). If DAVTEMP is above Thigh or is below Tlow, only a fraction of the day is considered for vernalisation. Vernalisation is achieved when VernalDay exceeds the threshold set by DayVernalMax.
The SimComponent calculates daylength for each day with the function "calculateDAYL" based on the latitude (cLatitude) of the simulated location. Then the daylength is compared with the crop requirements in the user-defined photo response table (cPhotoresponse).
== response to vernalisation and daylength ===
Changes in daylength and vernalisation modify the daily rate of effective temperature (rTSUMEFF_BaseAnt, rTSUMEFF_BaseMat). The modification is calculated by multiplying rTSUMEFF_BaseAnt (rTSUMEFF_BaseMat) with either the photoresponse factor (PhotoresponseFactor) or the vernalisation factor (vernFactor) whichever is smaller.
Before anthesis:
\[ \begin{eqnarray} RTSUM & = & rTSUMEFF_BaseAnt \cdot Min(PhotoresponseFactor, vernFactor) \end{eqnarray} \]After anthesis:
\[ \begin{eqnarray} RTSUM & = & rTSUMEFF_Mat \cdot Min(PhotoresponseFactor, vernFactor) \end{eqnarray} \]After anthesis, no daylength effects are taken into account (Photoresponsefactor = 1).
References: Goudriaan, H.H. Van Laar, 1994. Modelling Potential Crop Growth Processes, Kluwer Academic Publishers, Dordrecht (1994) 238 pp
Class is stateful by keeping the vernalDays in the instance.| Content Type | Name | Description | Data Type | Unit | Min Value | Max Value | Default Value |
|---|---|---|---|---|---|---|---|
| constant | cApplyPhotoresponse | Flag to activate photo response (True: daylength sensitive crops) | BOOLEAN | 1 | - | - | true |
| constant | cApplyVernalisation | Flag to activate vernalisation (True: crops requiring vernalisation for flower initialisation | BOOLEAN | 1 | - | - | true |
| constant | cLatitude | Latitude of the simulated location | DOUBLE | ° | 0.0 | 90.0 | 60.0 |
| constant | cPhotoresponseTable | Crop specific photo response table as function of daylength in hours | DOUBLEARRAY | 1 | - | - | [Ljava.lang.Double;@4c5da4f9 |
| constant | cThigh | Upper temperature threshold for vernalisation; days with higher mean air temperature are not fully considered as a vernalisation day | DOUBLE | °C | -40.0 | 50.0 | 10.0 |
| constant | cThighCritical | Upper temperature threshold for vernalisation; days with higher mean air temperature don't contribute at all for vernalisation day | DOUBLE | °C | -40.0 | 50.0 | 17.0 |
| constant | cTlow | Lower temperature threshold for vernalisation, days with lower mean air temperature are not fully considered as a vernalisation day | DOUBLE | °C | -40.0 | 50.0 | 3.0 |
| constant | cTlowCritical | Lower critical temperature threshold for vernalisation, days with lower mean air temperature don't contribute at all for vernalisation day | DOUBLE | °C | -40.0 | 50.0 | -4.0 |
| constant | cVernalDaysMax | Crop specific maximum number of days required for vernalisation | INT | K | 0 | 400 | 70 |
| constant | cVernalDaysMin | Crop specific minimum number of days required for vernalisation | INT | K | 0 | 100 | 10 |
| input | iDAVTMP | Daily mean air temperature | DOUBLE | °C | 0.0 | 50.0 | - |
| input | iDevStage | Development stage of the crop (1.0=anthesis, 2.0=physiological maturity) | DOUBLE | 1 | 0.0 | 3.0 | - |
| input | iDoSow | true if sowing day | BOOLEAN | 1 | - | - | false |
| input | iTSumBaseAnt | Daily effective temperature before anthesis | DOUBLE | K | 0.0 | 10000.0 | - |
| input | iTSumBaseMat | Daily effective temperature after anthesis | DOUBLE | K | 0.0 | 10000.0 | - |
| state | sPhotoresponseArray | Photo response array as function of daylength in minutes | DOUBLEARRAY | 1 | 0.0 | 20.0 | - |
| state | sVernalDays | actual Vernal Days | DOUBLE | 1 | 0.0 | 400.0 | 0.0 |
| DayLength | Day Length in minutes | INT | min | null | |||
| PhotoresponseFactor | daily photoresponse factor | DOUBLE | 1 | null | |||
| RTSUM | Daily effective temperature used to calculate the temperature sum and development stage at a given day | DOUBLE | K | null | |||
| VernalisationFactor | daily vernalisation factor | DOUBLE | 1 | null |