| Summary: | The seasonal timing of plant development is regulated by environmental cues. Flowering time is influenced by the temperature and photoperiod experienced during vegetative growth, while germination timing is affected by temperatures during seed maturation and after dispersal. The timing of each developmental transition also determines seasonal conditions experienced during subsequent life stages, however the significance and stability of these interactions are not well understood. This work aimed to further an understanding of the environmental regulation of plant phenology by creating a multi-stage life history model based on Arabidopsis thaliana. Laboratory and field studies were used to inform predictive models of seed development and seed dormancy. The time required to complete seed development was mainly affected by temperature, and was therefore sensitive to seasonal flowering time. Mean daily temperatures at the end of seed maturation had the greatest influence on rates of primary dormancy loss, and post-dispersal temperatures determined rates of secondary dormancy induction. Germination probabilities were predicted by modelling frequencies of primary and secondary dormancy within the seed population. This revealed an abrupt switch from low to high germination when mean daily temperatures exceeded 14°C. Thermoinhibition was also predicted at high temperatures due to rapid secondary dormancy induction. Combining models with a previously described model of flowering time provided a framework for investigating the effects of perturbations on entire life history phenology. Seed set timing in spring and winter annuals was consistently predicted to coincide with mean daily temperatures of 14°C in locations across Northern Europe, resulting in the production of both dormant and non-dormant offspring. Phenotypic plasticity at each growth phase also served to buffer against modest perturbations in germination date, flowering date, and climate in order to maintain these specific dispersal conditions. This result was interpreted as evidence for a robust bet-hedging germination strategy.
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