Effect of nine different gibberellins on stem elongation and flower formation in cold-requiring and photoperiodic plants grown under non-inductive conditions

Abstract

The effect of gibberellins A1 through A9 on stem elongation and flower formation in five plants was tested. The plants wereMyosotis alpestris and a biennial strain ofCentaurium minus (cold-requiring plants),Silene armeria andCrepis parviflora (long-day plants), andBryophyllum crenatum (a long-short-day plant). The two former plants were maintained on non-inductive temperatures and long days, the three latter on short days, InMyosotis, flower formation was only obtained with GA7 and GA1, the latter being relatively less active. InCentaurium GA3 was the most effective, followed by GA1, GA4 and GA7 and perhaps GA5 and GA9. InSilene, flower formations was induced only by GA7. InCrepis, the most effective gibberellins were GA4 and GA7, inBryophyllum, GA3, GA4 and GA7. Thus, the different gibberellins exhibited considerable differences in their activity with respect to flower induction, and different plants exhibited in this respect certain specific differences in their sensitivity to the various gibberellins. Except inCrepis, flower initiation as a result of gibberellin treatment was always preceded by substantial stem or internode elongation; however, the correlation between the effect of the different gibberellins on stem elongation and flower induction was not in all cases complete. No correlation of the flower-inducing and elongation-promoting activity with the chemical structure of the different gibberellins could be recognized.