The relationship between gibberellin and floral stimulus inBryophyllum daigremontianum

Summary

The long-short-day plantBryophyllum daigremontianum initiates flower buds both upon change from long to short day and after gibberellin application in short day only at night temperatures of 11° and 15°C, but not at 19°C.

Flowering of receptor scions in long day or short day takes place just as easily when the donor stocks have been induced by the shift from long day to short day or by gibberellin treatment in short day. Leaves taken from gibberellin-induced plants can also function as donors, even better so than photoperiodically induced leaves. Receptor scions induced by gibberellin-treated donors can in turn induce other vegetative scions (indirect induction).

Flower formation induced by the change from long day to short day as well as by gibberellin treatment in short day is always associated with an increased length of newly formed internodes.

It is concluded that gibberellin and the floral stimulus are not identical, but that gibberellin is a factor which normally limits production of the floral stimulus inBryophyllum under short days, and that the shift from long day to short results in an increase of the gibberellin level in the plant.