Cold Acclimation in Plants
Species Responding Directly to Low Winter Temperatures. Plants growing in regions with a mild winter or in habitats shielded from severe frost acquire greater resistance in the cold season as a direct consequence of the progressive drop in temperature. This enhanced resistance may be due simply to a lowering of Tf and Tsc, or to the acquisition and further development of freezing tolerance. However, if the plants are protected from cold they can remain at a low level of resistance throughout the year. This is the situation in the rhizomes of the cosmopolitan fern Pteris aquilinum, although not in other ferns of the temperate zone (Kappen 1964). A further example is provided by the observation of Larcher (1954) that the leaves of olive trees cultivated in glasshouses exhibit damage at any time of year at −6 °C, whereas under Mediterranean winter conditions they tolerate temperatures down to −10 °C. A similar kind of behaviour is seen in woody plants of the subtropics (e.g. Salix safsaf, S. tetrasperma: Sakai 1978, and Pinus caribaea: Oohata et al. 1981) and in many herbs.
KeywordsWoody Plant Cold Acclimation Freezing Tolerance Frost Resistance Cold Hardiness
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