Breaking the Dormancy of Snake's Head Fritillary ( L.) In Vitro Bulbs-Part 1: Effect of GA, GA Inhibitors and Temperature on Fresh Weight, Sprouting and Sugar Content.

Bulbs are the main vegetative reproductive organs of L. In nature, as well as in vitro, they become dormant and require low temperatures for further growth during the next vegetative period. In the present study, using 10 μM of gibberellic acid (GA), or gibberellin biosynthesis (GA) inhibitors-ancymidol (A) and paclobutrazol (P)-the dynamic changes in soluble sugars, fructose and glucose content, fresh weight and sprouting capacity were investigated. bulbs were cultured on medium with GA and GA inhibitors for 1, 2 and 5 weeks at two different temperatures (24 and 7 °C). GA improved bulb fresh weight, as well as sprouting percentage at both tested temperatures, compared to the control. The highest fresh weight increase (57.7%) and sprouting rate (29.02%) were achieved when bulbs were grown at 24 °C for 5 weeks. In addition, soluble sugar content was the highest in bulbs grown for 5 weeks on medium supplemented with GA. The main sugar in fritillary bulbs was glucose, while fructose content was lower. The sensitivity of bulbs to GA inhibitors differed and significantly affected sugar content in bulbs. To our knowledge, this is the first study of the sugar composition in bulbs during breaking of the bulb's dormancy and its sprouting.