VERNALIZATION

Vernalization

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.

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