Influence de la température sur la floraison du Lis blanc
The influence of thermoperiodic variations on the flowering of Lilium candidum is discussed here for the first time. Our experimentation was guided by our prior knowledge of the state of the apical meristem during the biological cycle. We concluded that forcing, to be effective, must occur on growing bulbs when the meristem of the lily is in the intermediate phase.We analyzed whether a cold period was necessary. When lily plants were cultivated for 8 days at 2 °C, the meristem reached the prefloral state at the beginning of the warm period (15 °C) which followed. The inflorescence is then in full bloom during the hot period (22 °C). Flowering occurs at the end of February.However, if the cold period is eliminated (with no change in the other periods), the terminal meristem loses its activity and differentiates. It is replaced by a small cluster of meristematic cells. A bulb develops at the top of the stem replacing the inflorescence. In this case, meristematic activity now begins at the axil of the leaves and the aerial stem. The axillary buds thus produced are a result of the combined actions of suppression of apical dominance after the loss of terminal meristem activity and the application of hot temperatures (22 °C).