Relationships between Changes in Air Temperature and Development of ‘Delaware’ Grape for the Past 48 Years in Habikino, Osaka, Japan

To understand the influence of yearly changes in air temperature on the development of grapes, we analyzed the records of air temperature and phenological events (budding, blooming) of ‘Delaware’ grape under open field conditions from 1963 to 2010 in Habikino, Osaka Prefecture, Japan using a generalized linear model (GLM) and model selection with Akaike Information Criterion (AIC). In this study area, the average temperature tended to rise over the 48 years. The dates of budding and full bloom became earlier. The average temperatures in February, March, and April were important factors influencing the dates of budding based on the GLM using AIC. This suggested that the dates of budding became earlier because of yearly temperature increases in February and March. The average temperatures in April and May were important factors influencing the dates of full bloom based on the GLM using AIC. This suggested that the dates of full bloom became earlier because of the earlier dates of budding and yearly temperature increase in May. In conclusion, the budding and blooming of ‘Delaware’ grape in Habikino, Osaka Prefecture have accelerated over the past 48 years: budding has been influenced by the yearly temperature increases February and March, and blooming has been influenced by the earlier of budding and yearly temperature increase in May.