Morphological and physiological aspects of phase transition in radicchio (Cichorium intybus L. var. silvestre Bischoff): the influence of temperature

摘要

Radicchio has a quantitative cold requirement. It could be induced to flower even when exposed to long days without previous cold treatment, but low temperature (5℃) caused earlier and more intensive bolting and flowering. The longer the cold treatment (up to 30 days), the more effective it was. The vernalizing effect of low temperature could be greatly reduced by fairly high temperatures (20-25deg ) given either before or after cold treatment. The latter were more effective in reducing bolting, theformer in delaying it. Heat given after cold treatment could reduce bolting, even when compared with non-vernalized controls. Heat treatment must follow immediately after cold treatment, since an intervening period at a neutral temperature (15-18deg ) stabilized the effect of the preceding cold treatment. Some of the anatomical and histological changes occurring during the transition of the apical meristem from the vegetative to the floral stage are described.