ISHS Acta Horticulturae 835: International Symposium on Source-Sink Relationships in Plants
FRUIT EFFECTS ON THE DRY MATTER- AND CARBOHYDRATE DISTRIBUTION IN APPLE TREES |
| Author: | F. Lenz |
| DOI: | 10.17660/ActaHortic.2009.835.2 |
| Abstract:
The fruit load has considerable influence on the development of the other organs in apple trees. With increasing fruit load growth of roots, stem, shoots and leaves is reduced when compared with non fruiting trees. Also fruit bearing trees contained less carbohydrate reserves, in particular of starch than non fruiting ones. This results eventually in irregular bearing, still a main problem for apple growers. To get a better understanding about the fruit effects on the vegetative growth of apple plants, ‘Golden Delicious’ trees on dwarfing rootstock M9 as used in high density orchards were raised and cultivated in sand filled lysimeters, facilitating the investigations on all plant organs including roots. The trees were daily supplied with a standard nutrient solution. For experiments one part of the test trees were allowed to set a full crop, while in the others all blossoms were removed at an early stage of development. Despite of the reduced vegetative growth, in particular of roots and leaves in fruit bearing trees, their total dry matter including that of fruits at the stage of harvest was similar or even higher than in non fruiting ones, indicating higher photosynthetic efficiency. Changes of dry matter and carbohydrates as glucose, fructose, sucrose, sorbitol and starch in organs of fruit bearing trees were investigated at monthly intervals. Apple trees not always grow under optimal conditions and therefore their growth behaviour as affected by cropping may be different to that at adequate water- and nutrient supply. Consequently fruit effects on growth and carbohydrate content were determined also on apple trees receiving different water- and nutrient levels. In addition effects of water logging received attention in regard to the dry matter -and carbohydrate distribution in fruit bearing and non fruiting trees. | |
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