Occurrence of Rind Disorders of 'Ootani' Iyo (Citrus iyo hort. ex Tanaka, var. Ootani) Fruit during the Pre-harvest and Storage Periods

Abstract

Experiments were carried out to clarify the causes of rind disorders in 'Ootani' iyo fruit. Rind disorders were observed at a maturing stage and during storage. The disorders were classified into three types, based on visible symptoms and causal factors. The first type occurs on the fruit surface only when the fruit on the tree are exposed to solar radiation and is designated as "sunscald". The causal factor seemed to be high temperature stress. The second type which occurs during storage at 5°C, is known as "Kohansho" by growers and shippers. The disorder is not conspicuous at harvest, but appears during storage where the fruit surface had been exposed to sunlight. The third type which is observed on the fruit exposed to -2°C during storage is called "Yakesho" which apparently differs from "Kohansho". The latter two types of disorders do not occur when the fruit are wrapped with polyethylene film bag after pretreatment at 20°C for two days. However, the rind disorders develop after the bag is removed. The exposure of harvested fruit to 50 ppm ethylene failed to prevent the disorders.