Influence of timing and number of consecutive inductive photoperiodic cycles on the flowering of lemna.

Requirements for flowering of the short day plant Lemna perpusilla Torr. strain 6746 can be studied by interposition of varying numbers of consecutive short days during 7 days of continuous light. A single inductive cycle can cause the formation of few flowers if it comes during the middle of a 7-day period of continuous light. Three inductive cycles cause 30% or more of the fronds to flower if the cycles are properly spaced in the 7-day period. The fact that timing of the inductive photoperiodic cycles is critical indicates the importance of development time and abortion of evoked floral primordia in the flowering response. These results are particularly useful in studies of processes occurring during induction.