Validated model for apple flowering prediction in the Mediterranean area in response to temperature variation

Abstract

Forceasting the phenological stages of fruit trees have a great meaning in term of making decisions about agricultural practices in orchards. Phenological modeling is one of prediction approches that play this role when it concerns flowering stages, particularly in the context of global warming mostly uncertain and continuously in change and the difficult adaptation of fruit trees to the future climatic trends. This study was aimed to develop and select a sequential model with best fit in three contrasting Mediterranean locations, including Moroccan sites characterized by mild climate in order to compare them with European sites (temperate climate), where phenological models were previously developed. Full flowering is the phenological stage investigated in this study. Statistical analysis of mean temperature during the period from October to April showed a significant difference between Moroccan and European sites. Consequently, full flowering dates observed in all locations demonstrated different behaviors in response to temperature variation during winter and spring period. Modeling process showed a sequential model with good fit to account for the full flowering stage observations with RMSE of 4.4 days of the validated data. Output of the fitted model revealed a delayed date of breaking dormancy and consequently a long endodormancy period in Morocco, intermediate in France and short in Italy, showing a gradient from the south (Morocco), where apple trees showed difficulty of adaptation due to lack of chilling, to the north areas.