Néoformation de boutons floraux sur culturein vitrode feuilles et de racines deCichorium intybusL.—Existence d'un état vernalisé en l'absence de bourgeons

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Abstract
SummaryFlower buds can be produced on tissues excised from the veins of leaves and the central core of roots of Cichorium intybus L. cultivar « Witloof », provided the plants have been vernalized beforehand. The flower buds were obtained in sterile culture on media devoid of added auxin, but containing coumarin (1 mg/1), the cultures being kept under long days. Uridylic acid (2 × 10−5)M did not cause flower-bud formation on unvernalized tissues. Experiments done in the Phytotron showed that most of the chicory plants are vernalized after 5 weeks at 5°C with 9-hour days of about 2,000 ft.c. light intensity. There is a physiological variability among plants grown from seed, as far as vernalization requirements are concerned. The formation of flower buds, produced adventitiously on tissues after the cold treatment demonstrates that, in order to become vernalized, a bud does not necessarily have to be subjected itself to low temperatures or to derive from a vernalized bud. Rather, it points out to the existen...