a1 School of Biological Sciences, University of Kentucky, Lexington, Kentucky 40506–0225, USA
The effect of dry storage under ambient laboratory conditions on after-ripening and survivorship was tested on seeds of the geographically-widespread Solidago altissima and S. nemoralis and the narrow-endemic S. shortii. Freshly-matured seeds of S. altissima collected in 1991 and in 1992 germinated to low or moderate percentages in light at 15/6, 20/10 and 25/15°C and to high percentages at 30/15 and 35/20°C, whereas those of S. nemoralis and S. shortii germinated to low percentages over the range of temperature regimes. After 0.8–1.8 years of storage, 1991 seeds of S. altissima incubated in light germinated to high percentages at 25/15, 30/15 and 35/20°C, those of S. nemoralis did so at 30/15 and 35/20°C and those of S. shortii at 20/10, 25/15, 30/15 and 35/20°C; 1992 seeds of all three species germinated to high percentages at 20/10, 25/15, 30/15 and 35/20°C. Freshly-matured 1991 and 1992 seeds of the three species germinated to low percentages in darkness over the range of temperature regimes, and only seeds of S. shortii germinated to high percentages after 0.8–1.8 years of storage. Compared with cold stratification, dry storage was only moderately effective in breaking dormancy in these three species. The primary difference in after-ripening of seeds of the three species was that seeds of the narrow endemic germinated to higher percentages in darkness than those of its two geographically-widespread congeners. Survivorship curves for 1991 and 1992 seeds of S. altissima and S. nemoralis and for 1992 seeds of S. shortii were of Deevey Type I; the survivorship curve for 1991 seeds of S. shortii was closest to Type II. Longevity of 1991 seeds of S. altissima, 1992 seeds of S. nemoralis and 1991 and 1992 seeds of S. shortii was <4.0 years, whereas that of 1991 seeds of S. nemoralis was <2.3 years; 5% of 1992 seeds of S. altissima were viable after 4.0 years.
(Received April 24 1997)
(Accepted May 22 1997)