In vivo and in vitro flowering response of chicory (Cichorium intybus L.):influence of plant age and vernalization

Chicory plants (Cichorium intybus L. var foliosum cv Flash) were tested wit h and without a 4-week-long cold treatment for in vivo and in vitro floweri ng potential every 2 weeks during the growing season. One hundred percent o f the plants harvested 112 days or later after sowing and then vernalized f lowered in vivo. In vitro, no vernalization was needed to initiate flowerin g-stems on chicory explants taken from roots of 100 days old and older. 5-A zacytidine, a DNA demethylation agent, increased the flowering percentage o n explants from young, vernalized roots but could not induce more than 15% flowering on young, nonvernalized roots. The greater flowering potential of chicory root explants in vitro when compared to plants of the same age tes ted in vivo was clearly established. This result suggests that some negativ e control on flowering was removed when root explants were excised and the main plant body discarded.