ISHS Acta Horticulturae 538: Eucarpia symposium on Fruit Breeding and Genetics
HOMOZYGOUS PLANT PRODUCTION IN APPLE BY PARTHENOGENESIS IN SITU : IMPROVEMENT OF THE POLLINATION STIMULUS FOR PARTHENOGENIC EGG CELL DEVELOPMENT |
| Authors: | K. De Witte, J. Keulemans |
| Keywords: | kaempherol, repeated pollination, flower type, temperature, pollen tube growth, embryo yield |
| Abstract:
One of the restricting factors for homozygous plant production in apple by parthenogenesis in situ is the low embryo yield after pollination with irradiated pollen. Such pollination is believed to stimulate parthenogenic egg cell development without fertilization. Therefore, we have studied several factors which can improve the stimulus effect of the pollination. Treatment of trees with kaempherol, which can stimulate pollen germination and pollen tube growth, resulted in inconsistent effects on embryo yield: two out of four years the effect was positive. Repeated pollination has an overall positive effect on embryo yield, although this effect was not observed with all cultivars in all years. When the first pollination was done with pollen irradiated at high dose, and the second one with pollen irradiated at low dose the embryo yield was much higher compared to two pollinations with pollen irradiated at high dose. Pollination of one stigma with ‘low dose pollen’ and the other four with ‘high dose pollen’ resulted in higher embryo yield compared to a pollination of all stigmas with ‘high dose pollen’. A better embryo yield was obtained for king flowers compared to lateral flowers in a cluster. This effect was observed in all cultivars and for pollen treated at low and high dose. In our experiments high temperature stimulated pollen tube growth, resulting in a higher number of pollen tubes reaching the ovule. These results were obtained with pollen irradiated at low and high dose. | |
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