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The induction in plants of the competence or ripeness to flower by the influence of cold, that is, temperatures below the optimal temperature for growth. Vernalization thus concerns the first of the three phases of flower formation in plants. In the second stage, for which a certain photoperiod frequently is required, flowers are initiated. In the third stage flowers are unfolded. See Flower, Photoperiodism, Plant growth
the reaction of a plant that is in the vegetative state to the effect of low, above-freezing temperatures (2°–10°C) for a certain period of time. Vernalization finds expression in the plant’s unique preparation to form the rudiments of flowers at the growing point. The German botanist J. G. Gassner was the first to study the phenomenon of vernalization (1918).
The phenomenon is characteristic of winter plants and some biennials and perennials. In some plants the formation of the flower rudiments may be an immediate result of vernalization. In many, for example, winter grasses, biennial henbane, and winter rape, flowering after vernalization will only occur during long days. Some plants show a capacity for vernalization at an early age. In winter grasses the reaction is observed during seed germination, and in biennial henbane it occurs after one month.
Vernalization is the result of the adaptation of plants to seasonal changes in climate. The physiological mechanisms of vernalization are probably associated with the formation of the plant hormones involved in inflorescence development.
The term “vernalization” is also used to designate an agricultural procedure by which the seeds of winter crops are exposed to a low, above-freezing temperature before planting so that the plants will blossom when planted in the spring. The technique is used in the selective breeding of plants.
V. Z. PODOLNYI