Cold hardiness (plant)

Article By:

Arora, Rajeev Deparment of Horticulture, Iowa State University, Ames, Iowa.

Last reviewed:December 2019

DOI:https://doi.org/10.1036/1097-8542.147900

The ability of temperate zone plants to tolerate and survive freezing temperatures. Freezing is a major environmental stress that inflicts injury to plant tissues. Lack of sufficient freezing (cold) tolerance is the most limiting factor for survival of many economically important plant species. Even if the direct freeze-thaw injury is not too severe, injured tissues can often serve as a primary infection court for plant pathogens (fungi and bacteria), which can ultimately lead to dead tissues. Most tropical and subtropical species have little to no freezing tolerance. However, plants from temperate regions have some “constitutive” freezing tolerance (present all the time, typically at low levels) and also have the genetic ability to significantly increase this tolerance when exposed to environmental cues signaling the arrival of winter, such as a period of low temperatures and/or short days. In temperate climates, such conditions are typically encountered in autumn by overwintering perennials (woody ornamentals, such as landscape plants and fruit trees), resulting in a seasonal increase in freezing tolerance. The ability of plants to increase freezing tolerance in response to changing environment is called cold acclimation (cold hardening). Deacclimation (dehardening) refers to reduction or loss of freezing tolerance originally attained through cold acclimation and, in nature, happens typically in early spring with the rising temperatures. Depending on the depth of deacclimation, it may be either irreversible or reversed by subsequent exposure to low temperatures that may cause reacclimation, that is, restoration of, at least, a portion of the lost tolerance. See also: Physiological ecology (plant); Plant cell; Plant growth; Plant pathology; Plant physiology

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