For Tomato, the timing of growth stage progressions through the season is dependent on both the variety and environmental cues such as day length, or temperature. The Tomato growing degree day model developed as part of the CROPTIME project at Oregon State University, uses heat units and time as a method to estimate plant phenological stages through the growing season. This can be helpful as a crop management tool, or to predict harvest timing.
Calculating Growing Degree Days
For this model, a lower temperature threshold of 45F and an upper threshold of 92F is used to calculate growing degree day accumulation beginning at the time of planting. Growing degree days can be calculated from daily high and low temperatures, or via the Pest Prophet app, which uses hourly temperature data for a given field. This can be used to predict flowering and harvest time for the following varieties: Big Beef, Indigo Rose, Monica, or New Girl, based on growing degree day accumulation.
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