The development of dormancy in bulblets of Lilium speciosum generated in vitro. II. The effect of temperature

Abstract

Delvallee, I., Paffen, A. andde Klerk, G.-J. 1990. The development of dormancy in bulblets of Lilium speciosum generated in vitro. IL The effect of temperature. Upon harvest, lily {Lilium speciosum Thunb. cv. Rubrum) bulblets generated in vitro under standard conditions (11 weeks at 2O''C) were dormant and needed a cold treatment prior to planting. During culture in vitro at 20°C, the bulblets proceeded through three phases: (1) at first they were non-viable and non-dormant (up to 5 weeks), (2) then viable and non-dormant (5-9 weeks) and (3) finally viable and dormant (from 9 weeks onwards). At I5°C, the bulblets became viable but did not develop dormancy, even after protracted culture. The restilts suggest that the development of dormancy depends upon an accumulation of 'heat units' occurring at temperatures higher than 15°C, At 25°C, the succession of the three phases occurred more rapidly than at 20°C and heat units were acctimulated more rapidly. Dtiring the third period, the chilling requirement increased showing that heat units continued to be accumulated during this period. Dormancy connotes an arrest of growth. In lily bulblets, however, the number of scales continued to increase after the induction of dormancy at 20 or 25°C. Many of the scales initiated before the onset of dormancy were formed by swelling of a petiole, whereas, after the onset of dormancy, all scales were formed directly from a primordium. We conclude that the development of dormancy corresponds to a switch in the development of the primordium. Thus, after the induction of dormancy the primordium lost the ability to become a leaf and always developed into a scale.

Hormonal control of dormancy and apical dominance in tissue-cultured plants

“…The term 'dormancy' is used for a wide range of phenomena differing with regard to the type of organ, the nature of dormancy (arrest ofgrowth in seeds or change in the direction of development in buds and bulbs; Young et al 1974;Delvallee et al 1990), the inducing stimulus and the conditions for release (cold storage under humid conditions or dry storage at room temperature). Thus, the question arises whether there is a general hormonal mechanism underlying dormancy.…”

Dormancy development during cold hardening of in vitro cultured Malus domestica Borkh. plants in relation to their frost resistance and cryotolerance

“…Endodormancy, a part of dormancy, refers to a state of buds regulated by internal factors where growth is possible only after plants have been exposed to sufficient amount of chilling (Lang et al 1987;Welling and Palva 2006). Dormancy of in vitro plants has been frequently studied on bulb plant species (Maksimović et al 2008;Kwang-Soo Kim et al 1994;Aguettaz et al 1990;Delvallée et al 1990). Some investigations of partial aspects related to endodormancy were made on fruit trees in vitro but there is a lack of studies for the investigation of dormancy induction and release in trees in vitro.…”

Endogenous Abscisic Acid and Dormancy of in Vitro Regenerated Lily Bulblets

“…Lily bulblets in vitro develop dormancy depending on the temperature during regeneration. At 25°C deep dormancy develops, at 15°C -no dormancy and at 20° C -intermediate dormancy ( 1,7). At higher temperatures no dormancy develops when an inhibitor of the AnA-synthesis is applied (6).…”