Comparison of different methods of grapevine yield Prediction in the time window Between fruitset and veraison

Aim: To compare grape yield prediction methods to determine which provide the best results in terms of earliness of prediction in the growing season, accuracy and precision. Methods and results: The grape yields predicted by six models ? one for use at fruitset (FS), two for use at veraison (V1 and V2), and three for use during the lag phase (LP40, LP50 and LP60) ? were compared to fieldmeasured yields. Regressions for the yield predicted by each model were constructed. The V1 and V2 models had the highest R2 (0.75) and efficiency index (EF; 0.67-0.71) and the lowest RMSE values (±16-17%, or <0.5 kg per mof row). The FS model had the same or similar R2 (0.58), EF (0.06) and RMSE (±30%, or