A comparison of the effect of temperature on grapevine phenology between vineyards

The variability of grapevine phenological stages under climate change has been studied in many winegrowing regions, with many reporting an advancement of the major phenological stages, particularly flowering, veraison and harvest. This study aimed to compare these regional patterns to integrate our understanding of grapevine responses. Average daily January–March (JFM) mean temperatures were correlated with day of year budburst (DBUD) and average daily springtime March–May (MAM) maximum temperatures were correlated with day of year flowering (DFLO), day of year veraison (DVER) and day of year harvest (DHAR) for 17 vineyards and showed an advancement of the associated phenological stage with increased temperature for each index. There were significant differences between vineyard groups for the rate of advancement of DBUD, DVER and DHAR which suggests that the response of phenological stage to temperature is not linear and varies between cultivars. Only the interval between DBUD and DFLO showed a significant shortening as related to MAMMax, suggesting that the advancement of grape maturity as related to increasing springtime maximum temperature is largely due to the shortening of the DBUD to DFLO interval.