THE NATURE OF SEED DORMANCY AND GERMINATION IN THE SALT MARSH GRASS <i>DISTICHLIS SPICATA</i>

Abstract

S ummary Distichlis spicata , a salt marsh grass, sets dormant seeds which exhibit a low‐temperature, after‐ripening requirement. In addition to stratification, localized scarification and nitrate are effective agents in breaking dormancy and promoting seed germination. The pericarp and/or testa are impermeable to organic plant‐growth regulators, but not to water or inorganic salts. Gibberellic acid and kinetin are ineffective in breaking dormancy and do not affect germination. Abscisic acid, however, effectively inhibits stratified and scarified seeds. Dormancy and germination appear to be hormonally controlled. It is suggested that the endogenous inhibitor constitutes a block to nitrate reductase activity in the endosperm. Presumably the inhibitor blocks specific DNA transcription sites in the aleurone cells, but can be overcome by after‐ripening (inhibitor decay), abrasion (inhibitor leaching) or nitrate induction.