Abstract: An in vitro shoot regeneration technique combined with colchicine application has been employed to produce hexaploid plants from leaf segments of the triploid cherry rootstock Gisela 6 (Prunus ceransus× P.canescens). Leaf segments were treated firstly with colchicine (0~200 mg. L-1) in the liquid modified WPM medium supplemented with auxin (IBA 0.5 mg. L-1) and cytokinin (BA 5.0 mg. L^-1) for five days and then transferred on the same regeneration solid medium with no colchicine for 56 days. In this case, putative hexaploid shoots were only regenerated from the leaf explants in the treatment of 50 mg. L-1 colchicine after 8 weeks on the regeneration medium. Flow cytometry was used for ploidy determination. The hexaploid plants were distinguishable from the triploid on morphological characters. All plants were successfully transplanted into the field and topworked on the sweet cherry trees to evaluate its agronomic traits.

Key words: cherry, dwarf, rootstock, colchicines, polyploid, hexaploid, regeneration