Low-temperature tolerance in cereals: Model and genetic interpretation

Exposure of plants to low temperature (LT) produces a myriad of measurable changes in morphological, biochemical, and pbysiological characters that are often highly correlated with plant cold tolerance. These complicated responses have made it difficult to separate cause-and-effect adjustments to LT, emphasizing the need for a descriptive framework for the integration of current knowledge so that research efforts can be better focused. The objective of this study was to construct a functional model that complies with the known LT responses of cereals so production risks, cause-and-effect processes, and genetic theories can be systematically investigated. In the model, a series of equations describe acclimation, dehardening, and damage due to LT stress. A modular design permits modification and allows the model to be interfaced with other simulation models that input or compute daily measurements of soil temperature and phenological development. LT tolerance is estimated on a daily basis relative to phenological stage and the input of a genetic coefficient is required. Operation of the model is consistent with recent interpretation of LT-gene regulation and it is especially sensitive to the switching signals that down-regulate LT-gene expression in plants maintained for long periods of time in the optimum temperature range far cold acclimation Simulation studies have also shown that small differences in cultivar genetic potential translate into large differences in LT tolerance when the cumulative effects of LT stress enter the critical range for overwinter survival. The model has been field validated for cereals overwintered in Saskatchewan, Canada, but it also has potential application in the simulation of LT responses of a wide range of species and climates.