• Horticultural Science & Technology
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• v.18 no.3
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• pp.360-367
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• 2000

'Yumyeong' peach has desirable characteristics of long shelf-life and specific non-melting nature with long harvesting period. However, some fruits harvested too late tend to show fruit pithiness symptom or internal breakdown. The study was conducted to investigate the differences between fruit flesh pithiness and internal breakdown symptoms, and to find out inducing factors of flesh pithiness in 'Yumyeong' peach. The incidence of flesh pithiness was higher in the fruits harvested late. Sugar and malic acid contents were not different between normal fruits and flesh pithiness fruits, but the acidity was significantly lower affected by low citric acid content in flesh pithiness fruit. In flesh pithiness fruits, calcium contents were low in both skin and flesh. Occurrence of flesh pithiness fruits was high in the years with low precipitation and high temperature for 2 months before harvest. In observations on morphological characteristics, the parts showing flesh pithiness consisted of smaller cells than the normal parts. Tonoplasts were disintegrated and the number of dead cells was high in internal breakdown fruits, while the tonoplasts were intact with contracted vacuoles in flesh pithiness fruits. Tylosises were observed in vascular tissues around the flesh pithiness, therefore, it was assumed that those tylosises restricts flesh tissue development resulting in flesh pithiness. Other varieties such as 'Fantasia' and 'Wolmi' also showed tylosis and smaller cells were observed in the flesh tissue of these cultivars, indicating abnormal growth of the flesh part. These results suggested the possibility of the occurrence of pithiness like symptoms in other peach varieties.