Meeting Abstract
The timing of seed germination strongly influences fitness and the expression of life cycles in annual plants. Understanding causes of variation in germination phenology under diverse environmental scenarios would help with efforts to predict plant performance across species ranges and under conditions of environmental change. Seed germination is regulated by innate dormancy induced at the time of seed maturation and by physiological responses to multiple seasonal environmental cues that vary over time, such as water availability, chilling, and temperature. We estimated physiological parameters associated with germination responses to environmental cues in different genotypes of Arabidopsis thaliana, and measured their dormancy cycling and germination time under field conditions. We employed a developmental threshold model of germination, flowering, and overall life-cycle expression to further predict the effects of variation in specific physiological parameters of germination on the expression of whole life cycles under different simulated seasonal environmental scenarios. Genotypes with different innate dormancy differed in germination time and dormancy cycling soon after dispersal, but continued dormancy cycling reduced differences among genotypes and reduced effects of starting conditions. Initial dormancy differences are predicted to influence life-cycle expression, but auto-synchronization mechanisms that act over time under variable conditions may contribute to canalized germination.
