Effects of light on in vitro tuberization of the potato cultivar Desiree and its relatives

Effects of different combinations of short days and dark treatment and different light intensities during the short days on in vitro tuberization of three potato cultivars were examined. Tuberization in Desiree, Cleopatra and Gracia was induced by short-day-treatment after 4 weeks culture under long days. The preserve natural endogenous hormonal balance of in vitro plantlets growth regulators were not added to the medium. The shorter the duration of short-days period the higher light intensity necessary for earlier tuber initiation.