Seed dormancy is an important trait refined by evolution, to aid survival in
adverse environments and to time germination and thereby select the correct habitat
and climate space for subsequent plant growth and reproduction. Depth of dormancy
changes continuously in response to the environment surrounding the seed and is
therefore a relative rather than an absolute condition. In nature, these changes are
triggered by seasonally characteristic environmental signals that are integrated by the
seed over time to select the optimum conditions for germination.
The mechanisms by which environmental signals influence this dormancy
cycling have been studied in the present work using a combination of eco-physiology
and molecular biology. Two contrasting Arabidopsis thaliana ecotypes Cape Verdi
Isle (Cvi) and Burren (Bur) have been compared. They are adapted to a hot dry (Cvi)
and a cool damp (Bur) climate and exhibit winter and summer annual phenotypes
respectively. Experimental work in the laboratory, controlled environment and field
has focussed on the effect of temperature, light and nitrate during seed maturation
and subsequent imbibition. The work was also extended to studying other life cycle
events such as the transition from vegetative growth to reproductive growth,
flowering and seed maturity. This work has extended our understanding of the
responses of life cycle traits to environmental signals. However, climates are
changing and further data was collected in a series of experiments in a unique
thermal gradient tunnel to provide insight into the impact of predicted global
warming scenarios on these traits. The results presented indicate the plasticity of the
plant life cycle and the extent to which global warming might affect this in
Arabidopsis, and how increased temperature is likely to affect different annual
phenotypes