SESSION IV – CONTROL OF VEGETATIVE GROWTH AND FLOWERING – RECENT ADVANCES IN THE UNDERSTANDING OF FLOWER FORMATION IN FRUIT TREES AND ITS HORMONAL CONTROL

Gibberellin-like growth regulators seem to play a paramount role, both as juvenility factors and as antagonists of flower formation in mature citrus and other trees.
The depressive effects of gibberellin on flowering are of a quantitative character, controlling the ratio of leaves to flowers in the flowering citrus branchlet.
Gibberellin distribution in the tree may explain, at least in part, the timing of flowering.

Antimetabolites of nucleic acid and protein synthesis promote flowering in citrus, possibly by preventing gibberellin synthesis or action.
Growth retardants disturbing gibberellin synthesis, may promote flowering in citrus and other trees, but their effects are not always reproducible.

The possible sources of native gibberellins and other growth regulators, and their seasonal activities, are discussed with the aim to better understand the mechamism of flower formation.

Symposium on growth Regulators in Fruit Production

S.P. Monselise

https://doi.org/10.17660/ActaHortic.1973.34.20