Seed dormancy: an update on terminology, physiological genetics, and quantitative trait loci regulating germinability

Dormancy is a form of developmental arrest and is an adaptive trait that promotes the survival of many organisms. In flowering plants, dormancy occurs in seeds and vegetative propagules (Lang 1996). Seed dormancy increases the distribution of germination over time, thus enhancing the survival of plants in an ever-changing environment. Seed dormancy is of intrinsic interest to weed scientists because it is one of 12 adaptive characteristics associated with weeds (Baker 1974). The sporadic emergence of seedlings derived from populations of dormant and nondormant weed seeds in the soil (Benech-Arnold et al. 2000; Forcella et al. 2000) is a key factor that dictates the need to apply weed control measures repeatedly within, between, and across growing seasons. My objective in writing this paper is to provide weed scientists, advanced students, and others with limited background information, some recent findings concerning the physiological genetics of dormancy, and steps toward identifying genes that directly regulate seed dormancy and germination. Molecular aspects of dormancy and germination will not be covered here because they have been reviewed recently (Bewley 1997; Li and Foley 1997). Readers can obtain additional and more extensive information on the biology and ecology of seed dormancy and germination from several recent books and reviews (Baskin and Baskin 1998; Benech-Arnold et al. 2000; Bewley and Black 1994; Casal and Sánchez 1998; Cohn 1996, 1998; Fennell 1999; Forcella et al. 2000; Hilhorst 1995, 1998; Hilhorst and Toorop 1997; Kelley et al. 1992; Kigel and Galili 1995; Simpson 1990; Vleeshouwers et al. 1995).