Abstract
We analyzed the relationships between the yearly variation in the developmental phase and fruit quality of the Japanese pear ‘Kosui’ (Pyrus pyrifolia Nakai) and climatic factors in Mie Prefecture between 1987 and 2004. The annual mean air temperature tended to rise at an annual rate of 0.07°C. This uptrend in the mean temperatures was especially remarkable from September to February. Along with the rise of temperature, the estimated date of breaking of bud endodormancy in ‘Kosui’ pear tended to be delayed at a rate of 0.49 day per year, possibly due to the rising temperatures during late autumn and winter. The dates of full bloom were negatively correlated with mean air temperatures at 10-day intervals from early February to mid-April and some of these mean air temperatures increased with advancing years. As a result, the dates of full bloom became earlier each year at a rate of 0.37 day per year. The date of peak harvest was positively correlated with the annual and became earlier each year at a rate of 0.32 day per year. The number of days from full bloom to peak harvest was not correlated with the annual. These results suggest that the developmental phase of ‘Kosui’ pear in Mie Prefecture is being influenced by global warming. However, the sugar concentration in the fruit was influenced by mean air temperature and mean solar radiation from middle July to middle August and mean precipitation from late July to early August, although, the yearly variations in sugar concentration in the fruit did not parallel the variations in annual mean air temperature.
