The response of short day plantChenopodium rubrum L. to abscisic acid and gibberellic acid treatment applied at two levels of photoperiodic induction

Abstract

Abscisic acid (ABA) (5 x 10 -4 M and 5 x 10 -5 M) and gibberellic acid (1 x 10 -4 M) was applied to the plumula of Chenopodium plants with partly (one dark period) or completely (three dark periods) fulfilled photoperiodic requirements for flowering. Morphological and cytoogical criteria were used to investigate the time-course of the differentiation of the treated shoot apices. Both substances were ineffective in increasing the mitotic activity of the shoot apex at the suboptimal level of induction. The degree of branching was temporarily stimulated by ABA and GA treatment under these conditions. Moreover, GA caused the elongation of the shoot apex. With the completely induced plants ABA hastened flowering and the rise in branching was observed in all the treatment 48 h following the application of growth substances.