Ethylene production trend in young ‘Fuyu’ persimmon fruit during attachment to or detachment from the tree

In persimmon (Diospyros kaki Thunb.) fruit, when they are attached to the tree there is only a small amount of ethylene produced throughout the whole development and ripening process. Ethylene was proposed to participate in fruit organ abscission. In an effort to understand the exact ethylene production trend in the process of fruit abscission, the ethylene production in ‘Fuyu’ persimmon fruit at young stage was studied. Fruit abscission was induced by certain stimuli from the tree, including 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU; a specific photosynthesis inhibitor), leaf-shading and defoliation treatments to leaves on the bearing shoots, and fruit exclusively abscised through abscission zone (AZ) between calyx and fruit, except that at very early young stage. The values of ethylene production of the abscised fruit on the abscising day ranged extremely wide both in fruit flesh (0-866 nL g^‑1 h^‑1) and calyx (0- 438 nL g^‑1 h^‑1). Under 2-h interval observation, ethylene production peak on the tree was found before fruit abscission, showing the following three patterns: fruit abscission either occur before, or right after the ethylene peak, or until the end of the degradation of ethylene. The sharp increase of ethylene production right before abscising is supposed to play a crucial role in inducing fruit abscission.