Dynamic Allocation of Sugars in Barley*

Allocation of carbon and nitrogen is a key factor for plant productivity. Measurements are carried out by tracing $^{\mathrm{11}}$C-tagged sugars using positron emission tomography and coincidence counting. We study the mechanisms of carbon allocation and transport from carbohydrate sources (leaves) to sinks (stem, shoot, roots) under various environmental conditions such as soil nutrient levels and atmospheric CO$_{\mathrm{2}}$ concentration. The data are analyzed using a transfer function analysis technique to model transport and allocation in barley plants. The experimental technique will be described and preliminary results presented.