The effects of temperature and solar radiation for 40 days from veraison to harvest time on the coloration of 'Kyoho' grapes were examined using vines different in the type of growing or the altitude of growing land.
The sideless polyvinylhouse at Jinzai and Honjou and the open air vineyard at Shimane University, where bunches were harvested in late August, were highest in the mean air temperature during the period. They were followed by the polyvinylhouse at Izumo and the glasshouse at Honjou whose harvest times were late July and early August.
The next was the open air vineyard at Yokota where the altitude was 350 m and bunches were harvested in early September. The lowest in the temperature was the open air vineyard at Shiojiri, Nagano where it was 889 m and they were harvested in the middle of September. As to the insolation duration during the period, the glasshouse at Honjou and the polyvinylhouse at lzumo were least among all of the places.
The open air vineyard at Shiojiri was highest in both the grade of skin color and the contents of anthocyanin in skin, whereas the glasshouse at Honjou and the polyvinylhouse at Izumo were lowest . A significant negative correlation was found between the mean value of daily mean temperature during the period in each sampling place and the grade of skin color, and also between the mean value and the content of anthocyanins in skin. However, no significant relation was found between the mean value and the content of either soluble solids or reducing sugar in juice. The content of free acids in juice tended to increase with the decrease of the mean value though the relation was not significant.
A significant negative relation was observed between the mean value of daily lowest temperatures during the period and the content of anthocyanins in skin, and also between the mean value and the content of free acids in juice. However, no significant relation was found between the mean value of daily highest temperatures during the period and each of the surveyed values on bunch quality. Further, the insolation duration during the period did not exhibit any significant relation with each of the surveyed values.
Although the compositions of anthocyanins in skin were different among the sampling places, they had no significant relation with the air temperatures or the insolation durations.