Compatibility and incompatibility in witloof-chicory (Cichorium intybus L.). 3. Gametic competition after mixed pollinations and double pollinations

Summary In witloof-chicory research was carried out on the occurrence of gametic competition after mixed or double pollinations with self-and foreign pollen. In part of the experiments flower heads were emasculated before pollination. Gametic competition was deduced from the percentages of hybrid seeds in the various experiments with flower colour functioning as a marker.Among self pollen parent (SPP) clones large differences occurred for frequency of germinated pollen grains after self pollination. These differences were positively correlated with the degree of self-compatibility (SC) of the clones. No significant differences for pollen germination rate were found.Among SPP clones large differences occurred for general hybrid producing ability (GHPA). There was a significant negative correlation between GHPA and SC of the clones. Among foreign pollen parent (FPP) clones, used for pollination of SPP clones, large differences occurred for general hybrid inducing ability (GHIA). Results from removing the stigma and a part of the style at varying intervals after mixed pollination and results from double pollination with a delayed second, FPP, pollination suggest differences in pollen tube growth rate in the apical part of the style and in the basal part and/or in the ovary. Besides general HPA and general HIA also specific HPA (SHPA) and specific HIA (SHIA) occur.