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

Abstract

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.

First-pollination primacy and pollen selection in the morning glory, Ipomoea purpurea

“…Results of sequential pollination studies on other species are varied. In a similar artificial pollination study on witloof chicory (Cichorium intybus), Eenink (1982) found that second pollinations delayed 60 minutes or more were ineffective.…”

Compatibility and incompatibility in witloof chicory (Cichorium intybus L.). 4. Formation of self-seeds on a self-incompatible and a moderately self-compatible genotype after double and triple pollinations

“…This may be ascribed to the above speculation . Another contribution to this enhanced self-seed formation is possibly made by a specific parental combination effect (SPP 560 x FPP 1045) which was observed earlier in Cichorium (EENINK, 1982) . Such parental effects resulting in gamete selection, have been found in various genera such as Allium (CURRAH, 1981) and Nemesia (ROBACKER & ASCHER, 1981) with styles capable to discriminate among pollen tubes from different pollinators .…”

“…SPP flower heads were not emasculated to approach as much as possible the natural and practical situation . Besides, emasculation may disturb the balance between male and female parts of the flower head (LINSKENS, 1964), influencing the frequency of self-seed formation (EENINK, 1982) .…”

“…Further details on Materials and Methods can be found in a previous paper (EENINK, 1982) as well as below .…”

“…If hybrids could be made by crossing self-incompatible (SI) lines, certain problems would not occur . For instance no self-seeds would develop during F 1 seed production and parent lines would not have to be screened for hybrid producing or hybrid inducing ability (EENINK, 1982) . However, selfing of severely SI genotypes for production and propagation of inbred lines has appeared impossible so far, despite application of various incompatibility weakening treatments used successfully in other crops (EENINK, 1981 …”