ISHS Acta Horticulturae 464: International Postharvest Science Conference Postharvest 96
CHLOROPHYLL FLUORESCENCE AND WHOLE FRUIT SENESCENCE IN ‘GOLDEN DELICIOUS’ APPLE |
| Authors: | N. Mir, R. Perez, R. M. Beaudry |
| Abstract:
Chlorophyll fluorescence was used as a non-invasive probe to study senescence in refrigerated air-stored apple fruit. 72% of variable fluorescence was quenched when the fruit surface was excited by a continuous source of light. Most of the quenching was photochemical. DCMU completely prevented the quenching of variable fluorescence in the whole fruit and photosynthetic O2 evolution in the peel discs. Under air storage conditions, all fluorescence parameters studied generally declined over time; and the rate of reduction was maximal from day 3 to 12. While the chlorophyll content, 10 mg·g-1 FW had a decreasing trend similar to that of fluorescence, the ratio of Chl a/b remained unchanged during the entire period of air storage. The capacity of peel discs to generate O2, via photosynthesis, declined as the fruit aged. The trend of the decline in O2 evolution was similar to the trend for Chl degradation. In contrast, variable fluorescence quenching was found to be independent of chloroplast photosynthetic activity in the later stages of fruit senescence. A Mehler type O2 reaction is suggested to account for large amounts of variable fluorescence quenching in apple fruit. Chlorophyll fluorescence appears to be a promising tool for estimating whole fruit senescence. | |
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