CAN CARBON ISOTOPIC DISCRIMINATION IN YOUNG PEACH TREES BE CONSIDERED AS A TOOL TO UNDERSTAND THE SEASONAL DYNAMIC OF THE STORED CARBON?

The ¹³C of the non-structural carbohydrates are expected to exhibit significant differences mainly related to the leaf gas exchange rates at the time of the photosynthetic assimilation.
We intend here to evaluate how far these differences could be informative about C storage and mobilization mechanisms.
Therefore, we evaluated the seasonal patterns of the ¹³C of starch and soluble sugars in young peach trees grown in containers.
Since this work was designed as a study of feasability it was limited to one organ: the rootstock-trunk bark.
The greatest seasonal changes occurred between March and July for both starch and soluble sugars.
Thus, the ¹³C increased significantly and passed from -25.6 to -23.4 for the soluble sugars and from -25.7 to -23.3 for starch.
The low values observed at bud-break stage raised the question of the nature of the stores involved in spring growth, namely of the possible contribution of carbon issued from amino acids degradation.
Moreover, a second significant seasonal effect was observed for starch between October and December when the ¹³C increased from -23.7 to -22.6. That increase is probably induced by the hydrolysis of the latest stored starch, which is those with the lowest ¹³C. In conclusion, if ¹³C isotopic discrimination could be informative on the seasonal dynamic of the C stores, a confirmation with labeling experiments is however required.
Labeling has moreover to be applied at high levels since the ¹³C of both starch and soluble sugars exhibits important variability.

IV International Peach Symposium

M.O. Jordan, A. Mariotti

Prunus persica, ¹³C isotopic discrimination, girdling, starch, soluble sugars, non-structural carbohydrates, seasonal patterns

https://doi.org/10.17660/ActaHortic.1998.465.41