The physiology of ornamental bulbous plants

Temperature Regulation of Endogenous Gibberellin Activity and Development of Tulipa gesneriana L.

“…The temperature reqtirements for growth and floral shoot development in tulip bulbs are generally satisfied by seasonal temperatures (7,12). Gill anti co-workers ( .5 6) and Dickev (3) have, however, reported that all or at least part of the low temperatuire reqtuiremeilt of tulip bulbs can be satisfied by treatment at 50 in a dry condition (precoolinig) which is then followved by root and floral shoot development at 130 or 180.…”

Mechanisms of vegetative propagation in bulbs : a molecular approach

“…The bulb has an apical meristem that according to the age and size of the bulb can be at the vegetative or reproductive state. Although all axillary meristems have the capacity to grow into daughter bulbs, on average three daughter bulbs of significant size are formed per bulb every growth cycle (De Hertogh and Le Nard 1993a;Le Nard and de Hertogh 1993;Rees 1966).…”

“…The second aspect is that axillary meristems are formed from outside to inside in the bulbs and that in principle, these initiated buds will make one or two scales and then enter a dormant state (Chapter 4, (Rees 1966)). However, the buds that are initiated when the shoot apical meristem (SAM) of their mother has transitioned into the reproductive state ('A and B' buds in tulip), are able to skip this kind of dormancy (Chapter 4 and (Rees 1968)).…”

“…Simultaneously, dormancy is triggered and a pro-longed period of cold is required for dormancy release and internal preparation for stem elongation and flower outgrowth in the next spring. This specific life cycle is not only seen in tulip, but is common for various bulbous species, including Tulipa, Crocus and Hyacinthus (Rees 1966;Saniewski et al 2000;Kamenetsky et al 2012).…”

“…However, by the end of the yearly growth cycle, only two to three daughter bulbs reach a size similar to the mother bulb and thus, have the capacity to flower in the next growing cycle (Rees 1966;De Hertogh and Le Nard 1993a;Le Nard and de Hertogh 1993). Since tulip bulbs rely on axillary bud outgrowth to reproduce asexually, but this mechanism does not distribute equally the resources to all the buds, it is of great interest to understand the bases of this vegetative propagation mechanism.…”