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TYPES OF DORMANCY

 

Dormancy- a state of inactive growth.

Purpose - to survive adverse conditions.
 

TWO TYPES OF DORMANCY
1) Quiescence - dormancy imposed by external or environmental conditions

    What triggers?
    a) Unfavorable environmental conditions
    b) External factor, such as hard seed coat

    What causes?
    Unfavorable environment; too dry, cold, hot, etc.

    How to overcome?
    Remove unfavorable environment
     
     

2) Rest or Physiological Dormancy - dormancy imposed by internal or physiological conditions.
    What triggers?
    Environment:
    a) short days (SD)
    b) decreasing temperatures

    What causes?
    Internal physiology is unfavorable:
    a) low level of growth promoters (e.g. auxin or gibberellic acid), and/or
    b) high level of growth inhibitors (e.g. ABA)

    How to overcome?
    Give period of cold between 32-45 oF (0-7 oC), which satisfies the chilling requirement.
     

    • chilling requirement - the number of hours of cold between 32-45 oF (0-7 oC)

    •                                    required to satisfy rest.