Abstract
The effect of the growth and development of pericarp tissues on the occurrence of the various types of black stain on fruit skin was examined in Japanese persimmons (Diospyros kaki Thunb.), ‘Fuyu’and‘Saijo’to define why ‘Saijo’is experientially said to be more susceptible to the disorders than‘Fuyu’.
1. Dotty type occurred most frequently in both cultivars. In‘Saijo’, disorders of vertically striped type gave the next higher rate of occurrence, followed by those of vertical line-like and broken line-like types. However, in‘Fuyu’, vertical line-like type occurred most often after dotty type, both of which occurred more often than the other types.
2. Broken line-like and cloudy types occurred mainly in the apical and median portions of fruit, while wavy and vertical line-like types were observed mostly in the basal portion in both cutivars.
3. In both cultivars, the rate of growth differed largely with the portions of fruit examined, decreasing successively from the base to the apex.
4. The cuticle layer of fruit in‘Saijo’was thinner than that in ‘Fuyu’in the early stage of growth. Also, the development of epidermal and sub-epidermal cells in‘Saijo’was inferior to that in‘Fuyu’.
5. The characteristic disorders in‘Saijo’were vertically striped and broken line-like types. These seem to be the typical ones caused by rapid enlargement of fruit in the late stage accompanied by the expansion of fine splits on the skin.
