Site‐specific Seed Dormancy in Spartina Alterniflora (Poaceae)

Seed dormancy in Spartina alterniflora was studied with regard to: 1) the specific site of the dormancy mechanism, and 2) the influence of three growth‐regulating substances: gibberellic acid, fusicoccin, and abscisic acid. The site of the mechanism was determined by assessing the germinability of surgically altered dormant seeds. Effects of the growth substances were determined by assessing the germinability of seeds incubated in their presence. Results revealed that dormancy could be broken surgically by altering the scutellum or chemically by applying fusicoccin. Dormancy could be restored by abscisic acid in the former case but not the latter. It is concluded that the dormancy mechanism is located in the scutellum, that it consists of at least two sequential steps, and that it involves a leachable chemical inhibitor.