Vernalization Mohsin Rafique, University of Sargodha sub campus Bhakkar

3. Introduction
Mohsin Rafique
Roll No 24
Bs. Botany
7th Semester
university of Sargodha
sub campus
Bhakkar

4. Vernalization
Promoting flowering with cod

5. Definition
• Vernalization is the process in which low
temperature given as a result plant show
flowering.
or
• Is the process whereby flowering is promoted
by a cold treatment given to a fully hydrated
seeds or to a growing plant.

6. • Dry seed do not respond to the cold
treatment.
• Due to vernalization the vegetative period of
the plant is cut short resulting in early
flowering.
• Without the cold treatment, plants that
require vernalization show delayed
flowering.

8. History
• Klippart,1857 – first notice that low
temperature requirement for flowering while
working with winter or spring wheat.
• Lysenko,1938- used term vernalization for a
low temperature promotion of flowering in
plants.

9. Vernalization
• Seeds are allowed to germinate for some time
given cold temperature 0 c to 5 c.
• The period of treatment varies from few days
to many weeks.
• Vernalization prepares the plants for flowering
• Vernalization induces the plant to produce a
hormone called vernalin.discovered by
Melcher 1936.

10. • The suitable temp for vernalization ranges
between 10 to 60 c.
• At high temp from 70 c onward response of
plant is decreased.
• At temp of about 120 to 140 is most ineffective
in vernalizing the plant.
• It is aerobic process and require metabolic
energy.

11. • In the absence of oxygen cold treatment
becomes completely inefficient.
• Sufficient amount of water is also essential.
• Dry seeds is not possible

12. Mechanism of vernalization
• Two theories
• 1. Phasic development theory
• 2. Hormonal theories

13. Phasic development theory
• Proposed by Lysenko in 1934
• According to this theory there is a series of
phases in the development of plant.
• Each phase is stimulated by an environmental
factor such as temperature and light etc.

14. There are two phases
• Thermophase
• Photophase
• Thermophase depends on temperature .
• Thermophase should be fallowed by
photophase which require light

15. Hormonal theories
• Melcher 1939
• He proposed that chilling treatment induce
the formation of new floral hormone called
vernaline.
• The hormone is transmitted to other parts of
the plant.
• The univernalized plant also initiates
flowering.

16. Devernalization
• The reversion of vernalization by high temp
treatment is called devernalizaztion.
• It is effected by treating the vernalized seed or
buds with high temp.

17. Practical applications
• Due to vernalization the vegetative period of
the plant is cut short resulting in an early
flowering.
• It increased the resistance of plant to fungal
disease.
• It increased the cold resistance of plant.
• It also helps in crop improvement.