ISHS Acta Horticulturae 311: International Walnut Meeting
STORAGE AND MOBILIZATION OF CARBON RESERVES IN WALNUT AND ITS CONSEQUENCES ON THE WATER STATUS DURING WINTER |
| Authors: | A. Lacointe, A. Kajji, T. Ameglio, F.A. Daudet, P. Cruiziat, P. Archer, J.S. Frossard |
| Keywords: | Starch, soluble sugars, 14C labeling, stress resistance, winter temperatures |
| Abstract:
The dynamics of carbohydrate reserves were investigated in the main parts of 3-year old walnut trees, in relation to other aspects such as water status and plant overwintering-and long term-survival. In autumn, ca. 90% of the starch reserves were located in the root system, mainly in the tap-root but also in lateral roots and particularly in the finest ones. A significant hydrolysis of starch to soluble sugars occurred in winter; correlatively, a significant increase of the vascular sap pressure was observed under the influence of low temperatures, suggesting a role in the resistance to dehydration beside that to frost. The dynamics of reserve mobilization in spring differed among organs. In those undergoing intensive growth the early starch depletion was quicker than in the tap-root, but later the tap-root was still being depleted while the growing organs were already restoring some starch. According to this 'dynamic' criterium, the tap-root, which underwent a long depletion to the benefit of the other parts, appeared as the specific reserve organ although starch storage occurred thoughout the plant. The mobilization rate of reserves was also dependent on their formation date: the autumn reserves were mobilized massively whereas the summer ones were only slightly. The 'excess' reserves are probably capital in case of environmental catastrophes. | |
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