Abstract
The anatomical and hormonal investigations on a long day plant Hyoscyamus niger L. during the time of the generative photoinduction have been conducted. The plants were grown during 75 days on a short photoperiod and then they were transferred to long day conditions. The earliest anatomical symptoms of flower initiation were noticed after four long photoperiods. The inductive photoperiod causes also a general increase in the amounts of phytohormones. During the flower evocation the intensive accumulation of cytokinins and gibberellins in leaves takes place. The post-inductive period, in which the development of flower elements happens, is characterized by changing amount of phytohormones. The content of hormonal substances is subjected to the rhytmical changes related to the periods of light and darknees in the twenty four hours' cycle.
Email this article 
