Towards the automatic simulation of fruit trees phenology: assessment of weather forecast data for calculating thermal time

Changes in the occurrence of meteorological events directly affect agricultural production. The increase in temperature has been linked to phenological changes in grapevines, which could have an impact on the cultural practices of several cultivars, as well as on fruit production. Then, the application of phenology models using the growing-degree days (GDD) has emerged as an easily accessible alternative for scheduling practices throughout the growing season. This study assessed weather forecast data from an ensemble of three global numerical models with weather stations, weather radar, and satellite data. The reference data were obtained from information recorded by automatic weather stations from six localities in central Chile (O’Higgins Region). The GDD was computed with a simple sine model, and the simulation presented values of root mean square error (RMSE) and mean absolute error (MAE) ranging between 4 – 8 °C, and 2.7 – 3.7 °C, respectively. Moreover, the index of agreement (d) presented values from 0.20 to 0.50, suggesting a low to medium agreement between observed and simulated data.