Abstract
A questionnaire about physiological disorders of Japanese persimmon (Diospyros kaki Thunb.) ‘Saijo’ sprouting from dormant buds was used to survey farmers in Shimane Prefecture. An increased prevalence of this physiological disorder was first noticed around 1995 and is now reported in more than 60% of the orchard investigated. The Ca, Mg, Mn, fructose and glucose concentrations in the branches of physiologically disordered trees was lower than that of sound trees. It was also observed that the tannin concentration in axillary buds increased in proportion to the degree of this physiological disorder, particularly in March. The tannin accumulated mostly in cells located at the basal part of bud meristems. In addition, cambium cells in physiologically disordered trees showed a lower cold tolerance.
In conclusion, the physiological disorder of Japanese persimmon ‘Saijo’ sprouting from dormant buds was caused by accumulation of insoluble tannin in the conductive tissues, which inhibited nutrient supply and water to the buds. It is also suggested that these physiological disorders might further deteriorate in the winter due to low temperatures.
