B. Photoperiodism as an oscillating timer. A more recent idea, and one that has greater support, is that flowering is controlled by an oscillating timer. C. Photoperiodic Control of Plant Growth. D. Photoperiodism summary. Temperature and flowering A. Overview.
Many plants require a cold treatment to induce flowering.
The effect can be qualitative or quantitative. Vernalization usually works in concert with photoperiod - in other words, vernalization is required to make the plants sensitive to photoperiod. Cold, actual temperature varies from -5 to 15 C. C. Receptor. Biennials not responsive as seeds. The meristem perceives cold treatment - grafting experiments and tissue culture experiments with rye.