Degree day model of table grape (vitisvinifera l.) phenology in mediterranean temperate climates

Vine phenology, like many other cultivated species, is highly determined by temperature and solar radiation. This relationship can be modeled using simple numerical expressions to quantify the effect of these climatic variables upon the development rate. This study validated the concept of thermal time, expressed by the concept of degree-days, for predicting the phenological evolution of several table grape cultivars (Vitisvinifera L.). To model vine phenology we used the Mitscherlich monomolecular equation and the Eichorn& Lorenz sequence. Phenology was evaluated for three cultivars throughout the growing season in several sites located in the climatic gradient ranging from a desertic to subhumid climates of Central Chile. Upon comparison, the resulting models for different cultivars showed a high degree of coincidence, especially during the embryogenic phase, which suggest the possibility of using a unique model, adapted to the characteristics of each cultivar.