Degree days (DD) and Growing degree days (GDD)
- At a given location, the period between planting and harvesting is not a specific number of calendar days but rather a summation of energy units, which may be represented as degree-days.
- A degree-day for a given crop is defined as a day on which the mean daily temp is one degree above the zero temperature (that is the minimum temperature for growth) of the plant.
- GDD or accumulated day degrees is also called as Effective Heat Unit.
- This is an arithmetic accumulation of daily mean temperature above certain threshold temperature. This is computed by using the formula suggested by IWATA (1984).
List of GDD for various crops
|
Crop |
Number of GDD baseline 100C |
|
Dry beans |
1100-1300 GDD to maturity depending on cultivar and soil conditions |
|
Sugar beet |
130 GDD to emergence and 1400-1500 GDD to maturity |
|
Barley |
125-162 GDD to emergence and 1290-1540 GDD to maturity |
|
Wheat |
143-178 GDD to emergence and 1550-1680 GDD to maturity (there may be confusion and Fahrenheit, 1680 is probably Fahrenheit) |
|
Corn (maize) |
800 to 1400 GDD to crop maturit |