Effects of pre‐ and post‐dispersal temperature on primary and secondary dormancy dynamics in contrasting genotypes of Arabidopsis thaliana (Brassicaceae)

Abstract

Germination is determined by the depth of primary dormancy and the dynamics of secondary dormancy induction. We assess how dark imbibition at cool temperatures influences primary dormancy breakage and secondary dormancy induction, and how the depth of primary dormancy influences secondary dormancy induction. We manipulated primary dormancy by maturing seeds at two temperatures (‘pre‐dispersal’) known to induce different levels of primary dormancy, and by employing genotypes that differ in primary dormancy. To assess primary dormancy breakage and secondary dormancy induction, seeds of each genotype and maturation treatment were imbibed in the dark at one of four temperatures (‘post‐dispersal’) for one of three durations. Germination proportions were recorded. Seed‐maturation condition and genotype influenced the degree of primary dormancy breakage in response to dark stratification and in the optimal temperature for dormancy breakage. Secondary dormancy induction was strongest in cool‐matured seeds and seeds stratified at warmer temperatures for longer durations. These effects were consistent across genotypes. Maturation temperature influenced the expression of genetic variation for primary but not secondary dormancy, which showed little genetic variation. Seed‐maturation temperature influenced primary and secondary dormancy induction by dark imbibition, and it also influenced the expression of genetic variation for temperature‐dependent dormancy breakage. Cool seed‐maturation induced primary dormancy in a genotype‐specific manner and enhanced secondary dormancy induction. Post‐dispersal temperature also influenced primary dormancy breakage and secondary dormancy induction. The observed interactions between primary and secondary dormancy, and between pre‐ and post‐dispersal temperature, are expected to influence life‐history expression in nature.