Growing Degree Days
Updated
by
Travis Bates
The development of plants depends on the accumulation of heat. Accumulated Growing Degree Days (GDDs) can be used to predict when a crop will reach a particular growth stage.
Two methods are presented by McMaster and Wilhelm (1997). Method 2 is used in the ZENTRA Cloud environmental model for GDD.
Method 2 implements a value check against the maximum (Tx) and minimum (Tn) temperatures before calculating Tavg.
Formula: Tavg = (Tx* + Tn*) / 2
Tx* and Tn* are the adjusted maximum and minimum temperatures.
- If Tx is greater than the upper temperature limit then Tx* is set to equal the upper temperature limit.
- If Tx is smaller than the base temperature then Tx* is set to equal the base temperature.
- If Tn is greater than the upper temperature limit then Tn* is set to equal the upper temperature limit.
- If Tn is smaller than the base temperature then Tn* is set to equal the base temperature.
METER Sensors that support GDD:
GDD
- Click the environmental model icon.
- Select Growing Degree Days.
- Enter a name for the model and a name for the chart.
- Enter values for the Maximum and Minimum(i.e. Base) temperature.
- A default air temperature measurement will be selected. Select a different measurement if desired.
- Optional: Enter the target GDD.
- Click Create.
Accumulated GDD
- Click the Vertical Ellipse icon.
- Select Stats.
- Toggle the desired measurements.
- Click Accept.
