  Compared with classical process-based models, the functional-structural plant
models provide more efficient tools to explore the impact of changes in plant
structures on plant functioning. In this paper we investigated the effects of
branches on the sourcesink interaction for the cotton plant (Gossypium hirsutum
L.) based on a two-treatment experiment conducted on cotton grown in the field:
the singlestem plants and the plants with only two vegetative branches. It was
observed that the branched cotton had more organs for the whole plant but the
organs on the trunk were smaller than those on the single-stem cotton. The
phytomer production of the branches was four or five growth cycles delayed
compared with the main stem. The organs on the trunk had similar dynamics of
expansion for both treatments. Effects of branches were evaluated by using the
functionalstructural model GREENLAB. It allowed estimating the coefficients of
sink strength to differentiate the biomass acquisition abilities of organs
between different physiological ages. We found that the presence of the two
vegetative branches increased the ground projection area of plant leaves and
had led to slight changes on the directly measured parameters; the potential
relative sink strengths of organs were found similar for the two treatments.
