HORMONE-INDUCED PARTHENOCARPY AS A SYSTEM FOR STUDYING FLOWER “QUALITY” IN COX’S ORANGE PIPPIN APPLE

The potential for set varies from flower to flower even when induced parthenocarpically by treatment of unpollinated Cox flowers with hormone setting mixture, indicating that flower "quality" is unrelated to the pollination process.
When hormone treatment was applied only to the flower calyx, the initial parthenocarpic set was very much greater than when application was made only to the pedicel base or rosette leaves.
Little acropetal movement of radioactivity occurred when hormone mixture containing labelled gibberellin was applied to the pedicel, whereas label moved basipetally when the calyx was treated.
This and other evidence suggests that the hormone treatment acts primarily at a site in the receptacle/ovary rather than by preventing abscission or by increasing vascularisation in the pedicel.

The possibility that some flowers fail to set due to a lack of photosynthate from rosette leaves has been considered, but evidence suggests that neither carbohydrate from leaf photosynthesis nor from stored reserves contributes greatly to the growth of flowers at or just after flowering.
That flowers were able to incorporate appreciable quantities of labelled CO₂ suggests that photosynthesis in the flower itself might be important for supporting initial fruitlet growth.
These results are discussed in the context of flower "quality".

VI International Symposium on Growth Regulators in Fruit Production

G.K. Goldwin

https://doi.org/10.17660/ActaHortic.1989.239.55