The Direct Action of the Floral Hormone in Silene armeria L.

Abstract

The difference in the time of flowering between an early line, «Early», and a very late line, «Late», of the long-day plant Silene armeria L. was studied. Juvenility, growth rate and leaf surface were not involved, whereas the intensity of the DNA-blocking in vegetative plants was: this blocking was relatively weak in «Early» and very strong in «Late», resulting in rapid and slow deblocking, in early and late flowering, respectively. When Early and Late were grafted on D(onor) Early in short day (SD), 100% simultaneous flowering occurred, so that the difference in time of flowering between ungrafted Early and Late had completely disappeared (Table 1). When, however, Early and Late were grafted on D Late in SD, no flowering followed. Upon transferring the plants to long day, very advanced and simultaneous flowering took place, so that again the difference in the time of flowering had completely disappeared (Table 2). These results are interpreted as a direct action of the floral hormone from the donors, leaving the blocking in the receptors Early and Late undisturbed. The remaining problem is the difference in action between the floral hormones from D Early and D Late. When «induction» is defined as deblocking, the term «indirect induction» must be considered as obsolete, since evidently no deblocking at all takes place as a result of grafting.