Frost Survival of Plants

Low temperature represents, together with drought and salt stress, one of the most important environmental constraints limiting the pro ductivity and the distribution of plants on the Earth. Winter survival, in particular, is a highly complex phenomenon, with regards to both stress factors and stress responses. The danger from winter cold is the result not only of its primary effect, i. e. the formation of ice in plant tissues; additional threats are presented by the freezing of water in and on the ground and by the load and duration ofthe snow cover. In recent years, a number of books and reviews on the subject of chilling and frost resistance in plants have appeared: all of these publications, however, concentrate principally on the mechanisms of injury and resistance to freezing at the cellular or molecular level. We are convinced that analysis of the ultrastructural and biochemical alterations in the cell and particularly in the plasma membrane during freezing is the key to understanding the limits of frost resistance and the mechanisms of cold acclimation. This is undoubtedly the immediate task facing those of us engaged in resistance research. It is nevertheless our opinion that, in addition to understanding the basic physiological events, we should be careful not to overlook the importance of the comparative aspects of the freezing processes, the components of stress avoidance and tolerance and the specific levels of resistance.

1. Low Temperature and Frost as Environmental Factors.- 1.1 Low Temperature Hazards.- 1.2 Cold, Frost, and Snow.- 1.3 The Occurrence of Cold, Frost, and Snow.- 1.4 Frost and Snow in the Plant's Environment.- 1.5 Time of Onset, Severity and Duration of Frost: The Freezing Risk.- 1.6 Temperature Fluctuations in Wintering Trees.- 2. The Freezing Process in Plants.- 2.1 Freezing of Water and Aqueous Solutions.- 2.2 Freezing of Plant Cells.- 3. Freezing Injuries in Plants.- 3.1 Typology of Freezing Mechanisms.- 3.2 Causes of Death by Freezing.- 3.3 Phenomenology of Frost Damage.- 3.4 Results of Freezing Injury and Chances of Recovery.- 4. Mechanisms of Frost Survival.- 4.1 Components of Frost Survival.- 4.2 Supercooling as a Survival Mechanism.- 4.3 Extraorgan and Extratissue Freezing.- 4.4 Comparison and Classification of Frost Survival Mechanisms.- 4.5 Survival at Ultralow Temperatures.- 5. Cold Acclimation in Plants.- 5.1 The Annual Course of Frost Resistance.- 5.2 The Seasonal Cold Acclimation Process.- 5.3 Environmental Control of the Level of Frost Resistance.- 5.4 Biochemical and Structural Changes During Cold Acclimation.- 6. Frost Resistance in Plants.- 6.1 Genetic Variation in Frost Resistance.- 6.2 Differences in Frost Resistance of Various Plant Organs and Tissues.- 6.3 Ontogenetic Variation in Frost Resistance.- 7. Regional Distribution of Plants and Their Adaptive Responses to Low Temperatures.- 7.1 Woody Plants Within the Tropics.- 7.2 Evergreen Broad-Leaved Trees and Shrubs.- 7.3 Transition from an Evergreen to a Deciduous Flora and Its Consequences for Frost Survival.- 7.4 Conifers.- 7.5 Mountain Plants.- 7.6 Trends of Adaptive Improvement of Low Temperature Resistance in Vascular Plants.- 8. Winter Damage as the Result of a Complexity of Constraint.- 8.1Winter Desiccation.- 8.2 Damage Due to Ice Encasement and Compact Snow.- 8.3 Harmful Effects of Heavy and Long-Lasting Snow Cover.- 8.4 Winter Survival: A Complex Response.- Determination of Frost Resistance for Comparative Studies.- Field Survival.- Artificial Freezing Tests.- Analysis of the Freezing Process.- Frost Treatment of the Samples.- Identification of Frost Injuries.- Quantification of Frost Resistance.- References.- Terminology and Definitions.- Taxonomic Index.