Vernalization is the effect of cold temperature on flowering.
- It prevents precocious reproductive development late in the growing season and enables the plant to have sufficient time to reach maturity.
- These plants remain vegetative during the warm season, receive low temperature during winter, grow further & then bear flower & fruits.
- Lysenko 1st reported the effect of cold temperature on flowering in the wheat seedling.
- Seen in winter varieties of annual plants (wheat, barley & rye), some biennials (cabbage, sugarbeet, carrot) & perennial plants (Chrysanthemum).
- The annual winter varieties plants also have spring varieties. Spring varieties are planted in spring and they flower & fruit in the same season.
- Winter varieties plants are sown in autumn & they form seedling in winter. These seedlings receive the cold treatment & resume growth in spring. They then flower and fruit in the summer.
- Low temperature required is from 0o to 5o.
- Vernalization is perceived by the meristems, shoot tip, root apex, developing leaves etc.
- The stimulus is transferred to all parts of the plant preparing it to flower.
- Vernalin (hypothetical hormone) is produced that prepares the plant for flowering. It itself cannot induce flowering.
- Devernalization occurs when a vernalized plant is exposed to high-temperature.