Variation of Sugar Content and Morphological Traits in Apple Fruit Depending on (Cultivars and Fruit Exposition in the Crown.

The sugar content in apple fruit differs depending on numerous factors: variety, culture technology, pedo-climatic conditions, fruit position in the tree crown etc. The influence of the cultivar and fruit exposition in the tree crown upon their sugar content, as well as upon some morphological traits of the fruit (weight, diameter and volume) at the Fruit Research Station Cluj, Romania were studied. Among the 12 analysed cultivars, the highest sugar content was recorded in 'Golden Delicious' (16.7°Bx) and 'Red Delicious' (15.8°Bx), regardless of the fruit exposition in the tree crown. At the other extreme are found the cultivars 'Pioneer' and 'Prima', in which the sugar content was of 12.6 and 13 .O°Bx. In most cultivars, the, fruit exposed southward in the tree crown have 'presented a lower sugar content than those exposed in the northern side. The difference is explained by the fact that, while the fruit advance towards the maturation process, due to the slightly more raised temperature (sunstroke), the respiration process intensifies, which determines the oxidation of a greater number of carbohydrates and, implicitly, the reduction of the sugar content. There were identified both phenotypic and genotypic negative correlations between the sugar content and fruit traits: weight, diameter, height and volume. Research is useful in the knowledge of the way in which fruit exposition influences the accumulation of sugar in the fruit, both for the producers and the consumers. [ABSTRACT FROM AUTHOR]