regions (e.g., Tulipa, Narcissus) require a relatively high temperature for flower induction, initiation
and early differentiation (Table 1). The further the temperature is from the optimal range, the lower is
the rate of floral meristem development.
For all studied species, low temperature experienced in summer suppresses flower induction and
initiation and leads to the formation of vegetative meristem [1,14,19–21].
High temperature (above 25–30 °C) experienced during the period when flower induction and
initiation normally occur also delays them, but under these conditions, the flowering capacity of plants
is maintained. The subsequent transfer to a lower temperature tends to favor the induction and
organogenesis of flower buds [1].
Once flower differentiation is completed, most bulbs require a period of low temperature (4–9 °C)
from the beginning of autumn, which enables stem elongation and anthesis in spring.