2019 年 75 巻 2 号 p. 67-75
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 2031-2050 and 10-25 days earlier in 2081-2100 than in 1981-2000. The skin color rating of ‘Kyoho’ in open field decreased from 9.4 in 1981-2000 to 7.9 in 2031-2050 and to 7.0 in 2081-2100 under the representative concentration pathway 4.5 scenario. The difference in skin color under different emission scenarios increased from around 2040 until the end of this century. Geographical distribution of the frequency of occurrence of poor skin color (skin color rating <7.5) showed that it will be necessary to introduce some adaptation measures for ‘Kyoho’ in open field in the plains of most areas except northern Japan by the middle of this century. Because air temperature during the coloring period drops with advancing phenology, a larger phenological shift led to darker skin. The skin color rating of ‘Kyoho’ at the end of this century remained above 7.5 owing to a phenological shift in plastic greenhouses with side film even in southern Japan. That of ‘Suzuka’, a superior-color cultivar, in plastic greenhouses without side film also remained above 7.5. A phenological shift or the use of a superior-colored cultivar would be effective as long-term adaptation measures.
