vernalization

Vernalization is a physiological process by which prolonged exposure to cold induces flowering in many plant species. The cold period typically occurs during winter and is required before the plant can respond to flowering signals in spring. In vernalization-requiring plants, insufficient cold can delay or prevent flowering despite other favorable conditions.

Molecularly, vernalization often involves relieving a repressive block on flowering. In the model plant Arabidopsis thaliana, prolonged cold reduces the expression of FLC, a key floral repressor, through an epigenetic silencing mechanism that involves vernalization pathway components and Polycomb group proteins. In cereal crops such as wheat and barley, vernalization engages distinct gene networks (including VRN genes) that enable flowering after winter. The common outcome is that plants become competent to flower only after a cold spell, typically in response to favorable photoperiod or growth conditions.

Temperature and duration requirements vary by species and cultivar. Vernalization usually occurs at temperatures near 0–5°C and can last from several weeks to a few months. Some seeds require cold stratification to break dormancy and germinate, which is a related but distinct process from vernalization in flowering plants.

Ecological and agricultural significance includes timing flowering to coincide with favorable spring weather and resource availability, thereby enhancing reproductive success. Vernalization is exploited in horticulture and crop production to control flowering time, often using growth chambers to simulate winter conditions. Climate change and variability can disrupt vernalization cues, potentially affecting flowering phenology and yields in vernalization-dependent species.