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PLANTS AND ORGANS THAT EXHIBIT REST
Rest is very common amongst temperate perennial plants, which are perennial plants that are native to the Temperate Climatic Zone.  Rest is a mechanism the plant uses to go dormant starting in the fall in order to survive the cold of winter.  Rest also assures flowering, vegetative growth and/or seed germination at the proper time in the spring.  The initiation of fall color is a sign of plants going into rest, and the emergence of flowers on fruit trees in the spring is a sign of plants coming out of rest.  It is the cold of winter that satisfies rest.  If a plant that is in rest is not exposed to the proper amount of cold, it may grow abnormally in the spring and/or may eventually die.  That is why we do not grow any of our native temperate trees as indoor plants, instead we use tropical trees that do not need cold to grow normally.

VEGETATIVE AND FLOWER BUD DORMANCY

Cold is required for some trees and shrubs to flower and/or start vegetative growth in the spring, especially temperate trees, shrubs and other perennial plants that are native to the Temperate Climatic Zone.

  • chilling requirement - the number of hours of cold temperatures between 32-45 o

  •                                    (0-7 oC) required to overcome rest (physiological dormancy).
    • flower buds - usually have a shorter chilling requirement 
    • vegetative buds - usually have a longer chilling requirement 
FLOWERING BULB DORMANCY

Cold is required for some bulb crops to flower; especially bulbs native to the northern part of the Temperate Climatic Zone, for example tulip.

  • cold storage or bulb chilling - a period of cold to satisfy chilling requirement of bulbs to

  •                                                 overcome flower bud rest (physiological dormancy).
    • usually 6-12 weeks at 35-45 oC (0-7 oC) in a cooler or refrigerator. 

 

SEED REST OR EMBRYO REST

Cold is required for some seeds to germinate, especially seeds of trees and shrubs which are native to the Temperate  Climatic Zone.

  • stratification - moist, cold (32-45 oF, 0-7 oC) storage  for 6-12 weeks required to 

  •                        overcome embryo rest (physiological dormancy).