CAUSES OF GENERATIVE DEVELOPMENT OF RADIC CHIO (CICHORIUM-INTYBUS VARFOLIOSUM)

The influence of temperature and daylength on flower formation of radi cchio was studied in growth chamber experiments. After temperature tre atments, transplants were planted in the field where the percentage an d date of bolting were recorded later. Studies on the effect of photop eriod took place in growth chambers only. Radicchio has no juvenile ph ase, seed vernalization is possible. Inductive temperatures range betw een 0 and 15 degrees C. The necessary duration of vernalization lies b etween 2 and 3 weeks at 5-10 degrees C. There are cultivars with a qua litative as well as a quantitative vernalization requirement. High tem peratures above 15 degrees C during transplant raising decreased bolti ng of radicchio (antivernalization). There were no effects of photoper iod during long days and high temperatures after vernalization.