A relationship between applications of indoleacetic acid and the high-intensity-light reaction of photoperiodism

Abstract

1. Experiments with Xanthium pensylvanicum Wallr. showed that the concentration of applied indole-3-acetic acid (IAA) necessary to inhibit flowering is dependent upon the length of previous exposure to high-intensity light and suggest that the IAA reacts with some product produced during the photoperiod. Such interaction presumably changes this light product in such a way that it is incapable of participating in the photoperiodic reaction to produce the flowering stimulus. 2. Results with Biloxi soybean (Glycine max) in similar experiments indicated that the degree of inhibition by applied IAA is proportional to the log of its concentration and suggest that the reaction may be a simple one and that the light product may possibly be a single compound, although such a conclusion must be most tentative. 3. If the high-intensity-light product should prove to be a single compound, then it seems probable that it will be found to be a direct precursor of the flower hormone.