Fig. 1: Schematic illustration of the interaction of genetic, hormonal, and environmental signals for regulation of seed dormancy and germination.

During seed development, genotype and environment influence the biosynthesis of abscisic acid (ABA) in the seed, inducing differing depths of primary dormancy. Dormancy is alleviated in these seeds with light, temperature, after-ripening, or chilling. Different genotypes or environmental conditions during seed filling can cause less ABA accumulation in the seed, leading to non-dormant seeds and removing the need for breaking the primary dormancy. Non-dormant seeds in conditions meeting their water and temperature requirements for germination then shift their gibberellin (GA) to ABA ratio higher, promoting germination. Seeds in which primary dormancy has been removed or non-dormant seeds under temperature extremes, anoxia, light conditions, or aging stress can experience relative dormancy, and with extended time in these conditions, can induce secondary dormancy. Secondary dormancy and relative dormancy can be alleviated with time under proper light, temperature, after-ripening, and/or chilling conditions.