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

Summary 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.With 2 Figures in the TextWork in part supported by the National Science Foundation, grants G-16408 and G-17483.