ISHS Acta Horticulturae 773: XXVII International Horticultural Congress - IHC2006: International Symposium on Citrus and Other Tropical and Subtropical Fruit Crops
CHARACTERIZATION OF FRUIT SUGAR ACCUMULATION AND MATURITY IN 'HARUMI' MANDARIN |
| Authors: | F. Takishita, K. Hiraoka, N. Muramatsu, M. Uchida |
| Keywords: | 'Kiyomi' tangor × Citrus reticulate, sugar concentration, citric acid, fructose, glucose, sucrose, harvest time |
| Abstract:
‘Harumi’ mandarin developed and released by the National Institute of Fruit Tree Science of Japan originated from ‘Kiyomi’ tangor crossed by ‘F-2432’ ponkan (Citrus reticulate). The fruit quality of this cultivar is excellent. It is seedless, easy to peel and has high sugar concentration. In order to harvest many fruits with high sugar content without peel damage caused by cold injury, it is important to study the fruit sugar accumulation and maturity to determine the optimum harvesting time of this cultivar. Brix value increased successively from August until January. The concentration of citric acid was more than 5% at August and it was not lowered to less than 1% throughout the harvesting duration. In the early stage of fruit growth, the major sugar components in fruit juice of ‘Harumi’ were fructose and glucose and the increase in their concentration was smaller than that of sucrose. Though the concen¬tration of sucrose was low in the early stage of fruit growth, it increased successively until January. In 2004 season, the total sugar concentration reached 11% in all fruits harvested from trees grafted on different rootstocks. However in 2005 growing season, only fruits harvested from trees grafted on ‘Flying Dragon’ trifoliate orange had 11% total sugar concentration. The ratio of monosaccharides to total sugar content was high in August (70-80%), and it decreased gradually to about 40% in January. Results of this study indicated that ‘Harumi’ fruits must be harvested until January before lower temperature prevails in the cultivation area. | |
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