| The conversion of apical meristem from the vegetative to the reproductive state involves two main aspects: (1) the transition from vegetative to generative development (induction and initiation); and (2) differentiation (organogenesis), maturation, and growth of the floral parts up to anthesis. In Allium species, physiological age and ecological background regulate the transition to the reproductive state. Species evolution and adaptation to environmental conditions in natural habitats greatly affect the process of floral induction. In bulbs with a thermoperiodic cycle, originating from the Irano-Turanian and Mediterranean regions, transition to florogenesis proceeds at relatively high temperatures during the growth period of the parent plant or during intrabulb developmental period. However, for further development, these species require a period of low temperatures. In species from temperate zones (Europe, Siberia), transition to florogenesis may occur during the growing stage and is affected by photoperiod and temperature. The subsequent stages of florogenesis (differentiation, scape elongation, floral development and anthesis) require a precise sequence of environmental conditions and, especially, temperature. In general, this sequence of environmental factors reflects the adaptation of the species to intrinsic conditions in their natural habitats and has to be taken into consideration during Allium growing and forcing. |
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