A Temperature Control from Heating Initiation Time to Full Bloom Stage on Forcing Cultured Japanese Persimmon (Diospyros Kaki Thunb.) 'Tone-wase'

Abstract

Temperatures higher than 8℃ are commonly used when forcing cultured Japanese persimmon (Diospyros Kaki Thunb.) 'Tone-wase', without consideration of the rest completion time that the trees require. For that reason, we investigated the relation between the period of temperatures less than 7.2℃ and the Development Index (DVI), sprouting and full bloom, and cumulative temperatures for developing leaves and buds afterward. Sprouting and full bloom occurred sooner following heating initiation when DVI was over 0.7. But growth days from heating initiation to sprouting increased by advancing of heating initiation if DVI was less than 1 when the maximum temperature was managed at 30℃ and the minimum temperature was managed at 15℃. When heating was performed from the end of December, the DVI was often less than 1. Therefore, it is appropriate to set a minimum temperature at the start as 8℃, then raise it 2℃ every about 10 days. Consequently, we should set the highest temperature as 30℃. Cumulative temperatures from sprouting to full bloom were about 700℃.