1. Leibniz Universität Hannover, Institute of Horticultural Production Systems, Section of Woody Plant and Propagation Physiology, Herrenhäuser Str. 2, D-30419 Hannover, Germany
2. Technische Universität Braunschweig, Institute of Pharmaceutical Biology, Mendelssohnstrasse 1, D-38106 Braunschweig, Germany