Control of flowering in bougainvillea "san diego red.": metabolism of benzyladenine and the action of gibberellic Acid in relation to short day induction.

Benzyladenine (BA) and short day (SD) induction promote and gibberellic acid (GA) inhibits flowering in Bougainvillea "San Diego Red." GA is an overriding vegetative signal maintaining plants in a vegetative state even when BA is applied in SD conditions. SD promotes a more rapid conversion of BA to the ribotide and other "polar derivatives" (containing adenine derivatives). This effect of SD on BA metabolism is seen in root, stem, and apical bud tissues and is completely prevented by prior or simultaneous application of GA. GA treatment reduces the rate of polar derivative formation to that found in plants held in long days. The working hypothesis is that SD promotes flowering in Bougainvillea owing to reduced transport of gibberellins from leaves to roots and apical buds permitting metabolism of cytokinin, and perhaps other purine bases, to more polar forms that are more readily translocated and active in promoting reproductive development of the inflorescences axes.