To develop a method for predicting the skin color of grape berries of three cultivars of Vitis labrusca L. × Vitis vinifera L. grown in Japan, we investigated the relationship between skin color and air temperature in the grape production areas of 18 prefectures. When mean air temperature during the 40 days before harvest date was ≥24°C, the skin color ratings of 'Kyoho', 'Pione', and 'Suzuka' were significantly negatively correlated with temperature. Skin color ratings decreased by about 1 unit per 1°C increase; at a given mean air temperature during this period, the rating of 'Suzuka' was higher (by 0.7 units) than that of 'Kyoho', which was higher (by 1.0 unit) than that of 'Pione'. Because an approach to predict harvest date has not been established, we developed a method to predict skin color at harvest based on air temperature after the fullflowering date. We found the times that had a strong negative correlation between the mean air temperature and the skin color rating at harvest was 43 days from 50 DAF (days after full flowering) for 'Kyoho', 46 days from 46 DAF for 'Pione', and 42 days from 52 DAF for 'Suzuka'. We obtained a linear regression equation for the relationship between the skin color rating at harvest and the mean air temperature during the periods. If the full-flowering date is known, it is possible to predict skin color at harvest by using this equation and the predicted air temperature after full flowering. We also developed a method for predicting anthocyanin contents in berry skins at harvest using significant regressions among the skin color rating, the skin anthocyanin content, and mean air temperature.

We evaluated changes in skin color of table grapes induced by climate change and the effects of a phenological shift caused by cultivation under cover and the use of a superior-color cultivar as adaptation measures. To assess the phenological shift, a model to estimate full-flowering date from air temperature was developed from observed full-flowering dated in Japan. A projected air temperature dataset until 2100 with 1-km resolution was applied to this model and the model to estimate skin color developed in the previous report. The full-flowering date of 'Kyoho' in open field gradually advanced and was about 9 days earlier in

To develop equations to predict the titratable acidity of grape berries at harvest from air temperature, we analyzed several years of datasets on wine grapes grown in experimental vineyards in seven prefectures and of table grapes grown in 37 prefectures in Japan. Although the number of days from the full-flowering date to harvest date varied with the cultivar, the temperature throughout the period of 40 to 50 days before the harvest date was the most strongly correlated with the titratable acidity of all tested cultivars. The titratable acidity at the harvest date of the wine grape cultivars decreased as the mean temperature of the period increased as did that of the table grape cultivars, although the latter did not decrease much above 24°C. The titratable acidity of the wine grape cultivars showed good linear regression with the mean temperature from 60 to 99 DAF (days after full-flowering) in 'Chardonnay', from 65 to 109 DAF in 'Monde Briller', and from 35 to 84 DAF in 'Colline Verte'. That of table grape cultivars grown in cold regions showed good quadratic regression with the mean temperature from 50 to 92 DAF in 'Kyoho', from 46 to 91 DAF in 'Pione', and from 52 to 93 DAF in 'Suzuka'. The titratable acidity of table grape cultivars grown in warm regions was estimated to be about 0.5 g/100 mL. These regression equations can be used to select cultivars to plant and to identify suitable regions for each cultivar, as well as to estimate changes in acid concentration under global warming. We also determined the relationship between the rate of acid reduction of the wine grape cultivars and temperature from serial measurements of titratable acidity to allow growers to predict the change in titratable acidity.

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This study estimated near-ground air temperature (T a) from Terra/ASTER-obtained land surface temperature (LST) for different land cover categories in a hilly region under a clear and calm night in winter. Temperature differences (ΔT) between LST and T a were related to the land cover categories and their spatial extents. In the extended area of forest land, spatially averaged ΔT in the area (ΔT m) was −0.1°C, and the relationship between LST and T a showed less variability (standard deviation of ΔT (SD)=0.8°C) and high correlation (coefficient of determination between T a and LST (R 2)=0.70). This result suggests we can evaluate T a directly from LST in this area. In the extended area of bare land, ΔT m , SD and R 2 were −1.5°C, 0.9°C and 0.85, respectively, which indicated that accurate estimation of T a is possible by correcting LST by ΔT m. In the extended area of artificial land, ΔT m showed statistically non-significant trend. In the case of intermingled area of more than one type of land cover, ΔT m, SD and R 2 were −0.8°C, 0.9°C and 0.71 in the forest land of the intermingled area, which suggested that we can estimate T a in this area precisely by correcting LST by ΔT m. In the bare land of the intermingled area, though ΔT m was −1.4°C, large variations (SD=1.4°C) and low correlations (R 2 =0.33) were found.