ISHS Acta Horticulturae 538: Eucarpia symposium on Fruit Breeding and Genetics
INFLUENCE OF POLLINATION TECHNIQUES, PLANT GROWTH REGULATORS FOR FRUIT SET AND EX VITRO GERMINATION ON HOMOZYGOUS PLANT PRODUCTION BY PARTHENOGENESIS IN SITU IN APPLE |
| Authors: | K. De Witte, J. Keulemans |
| Keywords: | beebooster, seed set, embryo set, embryo size, plant regeneration |
| Abstract:
The protocols for homozygous plant production in apple by parthenogenesis in situ are characterised by their low efficiency. We have tried to improve this efficiency by alternative pollination techniques, treatments with plant growth regulators for better fruit set and normal seed stratification followed by ex vitro germination of selected seeds. The experiments were done witch several cultivars, pollinated with pollen irradiated at different doses. In standard protocols flowers are emasculated and hand pollinated with irradiated pollen, which is a very labour intensive activity. In the case of self incompatible cultivars pollination can be done by a beebooster system. With this system good fruit set, seed set en embryo set was obtained in ‘Elstar’ and ‘Granny Smith’. The homozygous status of the resulting seedlings is still under investigation. On the other hand we have tried to improve fruit set (and embryo production) by application just after pollination of daminozide (an anti GA) and NAAm (an anti auxin derivat). The benefit of the improved fruit set of the NAAm application was lost due to a reduction of the number of embryos per fruit. Daminozide had a slight but positive effect on fruit set, seed set and embryo set, resulting in a higher embryo yield. Parthenogenic seeds were variable in size and weight. Seed set, seed weight and embryo set decreased with increasing irradiation dose. Parthenogenic seeds of normal size contain in most cases normal shaped but slightly smaller embryos than non-parthenogenic seeds. When parthenogenic seeds of more than 50 mg were stratified and sawed in Juffy plugs in a greenhouse, germination was slightly lower or comparable to that obtained in vitro and the percentage of putative homozygous plants was higher. | |
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