177 Changes of Fruit Structure and Sugar Contents during the Fruit Development Processes in `Yumyeong' Peach [Prunus persica (L.) Batsch

Abstract

`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 the whole fruit growth stages. 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 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 consisted of small and dense cells containing tannins. Therefore, it was found that the nucleus of peach consisted of inner epidermis and cells in the internal vascular tissues. The outer epidermis consisted of single layer cells at bloom and was changed into one to two layers by horizontal cell division 14 days after full bloom. At 30 days after full bloom, the epidermis consisted of five to six layers by vertical cell division. The cell layers of the outer epidermis gradually decreased to one to two layers at maturity. The observations on the changes in the epidermis confirmed that some of the cells of the hypodermis of peach fruit originated from the cells of outer epidermis. Tylosis was observed from 35 days after full bloom, and the size and number of tylosis increased until full fruit maturity. The sucrose content sharply increased from 50 days to 120 days after full bloom, then decreased slightly. After stone hardening ended, other solids showed a gradual decrease from 80 days after full bloom.