• 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.

• Horticultural Science & Technology
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• v.18 no.3
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• pp.353-359
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• 2000

'Yumyeong' is one of the most popular peach varieties in Korea. This study was conducted to monitor the developments of cells and tissues, and the changes in sugar contents during fruit growth and development. At bloom, there were two rows of vascular tissues, and the number and the position of internal vascular bundles were consistent during the fruit growth, however, the number of vascular tissues were increased and the distribution was irregular in the flesh tissues. The tissues between the inner integument and the internal vascular bundles showed different development characteristics from other parenchyma cells which were consisted of small and dense cells containing tannins. Such observation suggested that the stone of peach was consisted of inner epidermis and cells in the internal vascular tissues. The outer epidermis consisted of single layer cells at bloom differrentiated into 1-2 layers by horizontal cell divisions on 14 days after full bloom. On 30 days after full bloom, the epidermis was consisted of 5-6 layers by vertical cell divisions. The cell layers consisting the outer epidermis were gradually decreased to 1-2 layers at maturity. The observations on the changes in the epidermis confirmed that some of the cells consisting the hypodermis of peach fruit were originated from the cells of outer epidermis. Tylosis was observed from 35 days after full bloom and the size and number of tylosis were increased until full fruit maturity. The sucrose content showed the tendency of sharp increase from 50 days to 120 days after full bloom then decrease slightly. After when stone hardening ended, other solids showed a gradual decrease tendency from 80 days after full bloom.