The effect of environmental temperatures on the maturation of several fruits was investigated by exposing whole trees or fruits to different temperature regimes during the maturing period.
In ´Delaware´ grapes, with the increase in temperature around cluster from 15℃ to 30℃, anthocyanin and total acid levels in the berries decreased but sugar levels increased. When the whole vines were grown under 20℃, anthocyania and sugar contents in the berries and berry weight were always greater, but acidity was slightly lower than when under 30℃.
Anthocyanin content of `Kyoho´ grapes was increased with lowering in temperature around clusters from 30℃ to 15℃. Low night temperature around cluster, also, increased anthocyanin levels compared to high night temperature. Sugar levels in the skin were not affected by temperature around clusters. However, ABA contents in the skin of grapes exposed to low temperatures were much greater than those of grapes exposed to high temperatures. Free acid content in the juice of satsuma mandarin (Citrus unshia Marc.) fruits decreased more rapidly with an increase is fruit temperature. Total soluble solids and sugar content in the juice was highest at 23℃, followed by 30℃ and 15℃ in this order. In the peel, the lower the fruit temperature, the earier the chlorophyll degradation and carotenoid accumulation occurred. However, chlorophyll degradation was inhibited and little carotenoid pigments developed at 30℃.
Anthocyanin contents in the apple fruits increased at the lower fruit temperatures, but the degree varied among cultivars. And with the increase in fruit temperature, free acid levels in the fruit decreased but sugar levels increased regardless of cultivars. There was no relationship between anthocyanin levels and sugar metabolism in apple fruits.
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