Growing Degree Days [2.0]

Updated by Travis Bates

IN THIS ARTICLE

The development of plants depends on the accumulation of heat. Accumulated Growing Degree Days/Hours (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/GDH. 

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.

Support

Growing Degree Days/Hours can be calculated from any temperature measurement.

  • ATMOS 41
  • ATMOS 41W
  • ATMOS 14
  • VP-4
  • VP-3
  • ECT

New Growing Degree Days/Hours

  • On the     Data page, select    New Data.
  • Select Heat Units (GDD/GDH) as the type.
  • Select one or more temperature data sources.
  • Edit the data stream color.
  • Edit the data stream name.
  • Click the temperature to change the model variant to Growing Degree Days or Growing Degree Hours.
  • Enter values for the Base temperature and the Maximum temperature. The maximum temperature value is optional.
  • Select Create to finish.
  • The new data stream(s) will now be in your data list.

Growing degree days

Model variants

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