Cold Hardiness of Grapes: Definition of terms
Cold hardiness
is the ability to resist injury during exposure to low temperature.
Cold tenderness is the opposite
of cold hardiness.
Cold injury is the killing by
low temperature of some part of the vine.
Seriousness of cold injury is
indicated by the amount of decrease in fruit production and/or quality
resulting from cold injury.
Dehardening is the process
after the chilling requirement (rest) is satisfied whereby the plant or
tissue loses hardiness and is ready to resume growth.
Dormancy is the condition of a
bud or seed characterized by the lack of outwardly visible growth.
Double pruning is the cultural
practice whereby twice the number of buds dictated by the balanced pruning
formula are retained after an initial pruning in early to mid winter. A
second pruning is done after bud damage can be assessed and/or the threat
of spring frost injury is minimal.
Hardening is the process by
which a plant or tissue is made more resistant to any environmental
extreme such as low temperature.
Rest
is a state of suspended growth due to internal physiological blocks. Rest
is fulfilled by exposure to temperatures of 45°F (7°C) or less for an
extended period (chilling requirement). After the rest period is
satisfied, a plant may either break dormancy and begin to grow if
conditions allow, or may remain dormant if conditions do not favor growth.
