Development of dormancy in different lily genotypes regenerated in vitro

Dormancy development in four Lilium genotypes, L. speciosum, Star Gazer, C. King and Snow Queen regenerated in vitro was compared. Major factors influ encing dormancy development were the same for different genotypes and espec ially L. speciosum and Star Gazer, that are closely related, reacted simila rly. Temperature was the main factor in dormancy induction and breaking. Th e range of temperatures that induced dormancy and the level of dormancy tha t developed differed per genotype. In Star Gazer, dormancy developed gradua lly but in Snow Queen, dormancy developed very fast. The reactions to tempe rature, reflected the climate in the area of origin. Abscisic acid deepened the level of dormancy induced by temperature but had no effect under non-i nductive temperature conditions. When abscisic acid synthesis was blocked, no dormancy developed. Dormancy in all genotypes was broken by cold incubat ion for several weeks. The cold requirement of the genotypes differed in li ne with the natural winter conditions in their habitat. The effect of hormo nes on dormancy breaking was also investigated. A gibberellin treatment of 24 h broke dormancy in L. speciosum, Star Gazer and Snow Queen.