Drought effects in dock 1 Drought Stress alters Solute Allocation in

According to climate models, drier summers must be expected more frequently in 5 Central Europe during the next decades which may influence plant performance and 6 competition in grassland. The overall source-sink relations in plants, especially allocation of 7 solutes to aboveand below-ground parts, may be affected by drought. To investigate solute 8 export from a given leaf of broadleaf dock, a solution containing Co and Zn was 9 introduced through a leaf flap. The export from this leaf was detected by analysing 10 radionuclide contents in various plant parts. Less label was allocated to new leaves and more 11 to roots under drought. The observed alterations of source-sink relations in broadleaf dock 12 were reversible during a subsequent short period of re-watering. These findings suggest an 13 increased resource allocation to roots under drought improving the functionality of the plants. 14