Abstract
Sugar composition of apple fruits during maturation period was compared with fruits of 3 cultivars, ‘Jonathan’, ‘Golden Delicious’ and ‘Fuji’, grown at 4 or 6 different locations. The result was discussed in relation to the thermal conditions of the locations.
1. With ‘Golden Delicious’ and ‘Fuji’ fruits grown at Takatsuki where sugar determinations were started at immature stage, the ratio of sucrose to total sugar increased rapidly from the end of August or early September while those of glucose and fructose to total sugar decreased. With ‘Jonathan’, however, such changes in sugar metabolism were not clearly observed.
2. In most of the locations, the ratio of fructose to total sugar in ‘Jonathan’ and ‘Golden Delicious’ decreased with the advance of fruit maturation while the trend in the ratio in ‘Fuji’ was different dependent on locations. No clear difference was found in the ratio of fructose to total sugar among the different locations in all cultivars.
3. The ratio of glucose to total sugar was nearly constant or decreased gradually in all cultivars. General tendency was that fruits grown at cooler locations had lower glucose ratios than those at warmer locations during maturation period.
4. In ‘Jonathan’ and ‘Golden Delicious’, the ratio of sucrose to total sugar increased with the advance of fruit maturation in most of the locations, but in late maturing ‘Fuji’, changing patterns were different among different locations. In all cultivars, fruits grown at cooler locations generally had higher sucrose ratios than those at warmer locations.
5. The ratio of sorbitol to total sugar was low and no clear difference was found among different locations in all cultivars.
6. From these results, it is suggested that in general, apple fruits grown at cooler locations have higher sucrose and lower glucose ratios than those at warmer locations throughout the maturation period.
