Studies in seed dormancy : IV. The role of endogenous inhibitors and gibberellin in the dormancy and germination of Corylus avellana L. seeds.

The dormancy of freshly harvested hazel seeds appears to be induced by inhibitors occuring mainly in the testa and pericarp. Although d abscisic acid may not be one of the natural inhibitors involved, d,l abscisic acid has been shown to strongly inhibit the germination of hazel seeds, probably through its antagonism towards the action of gibberellin. Dry storage of hazel nuts causes a deeper state of dormancy (secondary dormancy) to be superimposed on the primary dormancy. It is suggested that secondary dormancy consists of a block to gibberellin synthesis. The essential effect of chilling intact hazel seeds, which is the natural means of breaking their dormancy, may be to activate the mechanism for gibberellin synthesis, the subsequent synthesis of gibberellin being thought to occur at the germination temperature (20°C) and not at the chilling temperature (5°C).