| 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 oF
(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).
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