While They Were Asleep: Do Seeds After-Ripen in Cold Storage? Experiences With Calendula

Abstract

<p>Methods to break seed dormancy are of great interest to plant propagators, with many papers on this topic presented at past I.P.P.S. meetings. For example, in Vol. 54 of our Combined Proceedings of the International Plant Propagators’ Society, there were reports on embryo culture to avoid dormancy (Douglas, 2004) and recommendations on dormancy-breaking techniques for Helleborus (Bush, 2004), Salvia (Navarez, 2004), and many wildflowers and grasses native to the North Central U.S.A. (Diboll, 2004). As propagators, we typically want quick methods that consistently result in high germination rates without large labor inputs. But if we can afford to be more patient, some seeds may eliminate their primary dormancy mechanisms during storage. This progressive loss of dormancy after maturity in “air-dry” seeds is known as after-ripening (Murdoch and Ellis, 2000). Typically, after-ripening is thought to occur under warm, dry conditions (Foley, 2000; Probert, 2000), but the literature of after-ripening is somewhat confusing. Simpson (1990) defined after-ripening in a more general way as “loss of the dormant state over some period of time through exposure of the seeds to a set of environmental conditions after maturation and separation from the parent plant.” The term has even been used to describe combinations of warm storage and the effects of stratification (Baskin and Baskin, 1988).</p>