ISHS Acta Horticulturae 564: IV International Symposium on Mineral Nutrition of Deciduous Fruit Crops
REGULATION OF N UPTAKE IN YOUNG PEACH TREES IN RELATION TO THE MANAGAMENT OF CARBON AND NITROGEN STORES |
| Keywords: | Prunus persica L., Soluble proteins, Starch, Soluble sugars, Plant growth |
| Abstract:
To evaluate how far carbohydrates play a role in the regulation of nitrogen uptake and N store management we manipulated (i) the C availability using trunk girdling or CO2 depletion, and (ii) N storage by applying 5 levels of fertilization in late summer. N uptake was reduced by both CO2 privation and girdling, but the C stores were affected only after girdling, which interrupts the photosynthate supply to the root. CO2 privation decreased the respiration losses and reduced the CO2 assimilation. On a daily basis, the C budget remained balanced. Girdling induced a starch accumulation in leaves and shoots and a starch depletion in roots and rootstock-trunk. The N store management was also related to C metabolism. N accumulated in the shoots from July to leaf fall, when C was assimilated in excess of growth requirements. The amounts of stored N were strongly correlated to those of the non-structural carbohydrates. Mobilization occurred in spring, when trees were not autotrophs for C. At that time growth depended on the amount of N provided the previous summer. These results are synthesized in a model which describes N uptake in relation to store management, growth and C availability. | |
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