Occurrence of Physiological Disorders in Japanese Pear Fruit and Advances in Research on these Disorders

Abstract

In this paper, I reviewed research studies and records of the occurrence of physiological disorders such as ‘Yuzuhada’ disorder, water core, and cork spot like disorder in Japanese pear (Pyrus pyrifolia (Burm. f.) Nakai) fruit. The incidence of these flesh disorders varied not only with the climate of the growing season and soil condition but also according to the tree age and cultivation techniques, such as pruning and fertilization. The histological and biochemical characteristics of the disorders differ from each other as follows: ‘Yuzuhada’ disorder refers to an increase in the thickness of the cell wall; the water core is the degradation focus of cell wall polysaccharides, and cork spot like disorder involves the suberization of cells in pear flesh. The common cause of these three disorders was considered to be competition for water between the fruit and leaves. This paper also discusses future trends in research on physiological disorders affecting Japanese pear fruit.