THEORETICAL AND EXPERIMENTAL DETERMINATION OF PHLOEM TRANSLOCATION SPEEDS IN GYMNOSPERM AND ANGIOSPERM TREES

In trees, carbohydrates produced in photosynthesizing leaves are transported to roots and other sink organs over distances of up to 100 m inside a specialized transport tissue, the phloem.
Carbohydrate translocation in the phloem is a fundamental aspect of tree physiology with relevance for tree crop performance and climate change.
In this paper, we present theoretical and experimental data on the carbohydrate transport speed inside the phloem.
Theoretical modelling with a simple transport resistance model and the limited available experimental data indicate a generally slower transport speed in gymnosperm trees compared to angiosperm trees of similar height.
We describe a novel approach to measure phloem transport speed in trees by non-invasively monitoring ¹⁴C-assimlate transport that could be instrumental to test this hypothesis.
Experimental methods to quantify phloem transport allow testing of predictions of simple theoretical models and defining parameters essential to develop more comprehensive models.

IX International Workshop on Sap Flow

J. Liesche, A. Schulz, K.H. Jensen, P. Minchin, T. Bohr

phloem transport, carbon allocation, resistance model

https://doi.org/10.17660/ActaHortic.2013.991.5