Poster: Water relations
Abs #
151: The Mechanism of Fruit Cracking in Wax Apple (Syzygium samarangense Merr.et perry )
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Presenter: |
Lu, Pei-Luen , lufreda@yahoo.com.tw |
Authors | Lu, Pei-Luen (A) Tseng, Menq-Jiau (B) Lin, Chin-Ho (A) | | Affiliations: |
(A): Department of Life Science, National Chung Hsing University
(B): Department of Horticulture, National Chung Hsing University
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Fruit cracking commonly occurs in many fruits and usually results in considerable financial loss to the grower. However, the physiological mechanism of fruit cracking is still not understood. Wax-apple (Syzygium samarangense Merr.et perry) is one of the important economical valuable fruits in Taiwan. The wax-apple fruit is conical with a spongy center tissue that can develop cracks during the fruit maturation stage in all seasons. The aim of this study was to find the possible factors associated with fruit cracking in wax-apples and to explore the possible mechanism of cracking. Total soluble sugars, osmotic potential, water potential, turgor pressure, polygalacturonase activity, and the total titratable acids were measured in cracked and normal fruits. When cracked fruit were compared with normal fruit the following differences in mean values were observed: the contents of total soluble sugars were 20% higher in cracked fruit than in normal fruit; osmotic potential was 60% lower; water potentials were similar; turgor pressure was 60% higher; specific activity of polygalacturonase (PG) was 131% higher; and total titratable acids were similar. Based on the above results, it is hypothesized that the increase in total soluble sugars during fruit maturation leads to decreased tissue osmotic potential. Water absorption in response to this decreased in osmotic potential can cause cells to swell in response to increased turgor pressure, which ruptures the cells and tissues. On the other hand, the increase in polygalacturonase activity in the plant cell wall weakens the cell wall. The combined results lead to fruit cracking. ( This work was supported by a grant from The National Science Council, Taiwan, NSC 92-2815-C-005 -029 -B.)
