A comparative study of the seed germination biology of a narrow endemic and two geographically-widespread species ofSolidago(Asteraceae). 5. Effect of dry storage on after-ripening and survivorship

Abstract

AbstractThe effect of dry storage under ambient laboratory conditions on after-ripening and survivorship was tested on seeds of the geographically-widespreadSolidago altissimaand S.nemoralisand the narrow-endemicS. shortii. Freshly-matured seeds ofS. altissimacollected 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 ofS. nemoralisandS. shortiigerminated to low percentages over the range of temperature regimes. After 0.8–1.8 years of storage, 1991 seeds ofS. altissimaincubated in light germinated to high percentages at 25/15, 30/15 and 35/20°C, those ofS. nemoralisdid so at 30/15 and 35/20°C and those ofS. shortiiat 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 ofS. shortiigerminated 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 ofS. altissimaandS. nemoralisand for 1992 seeds ofS. shortiiwere of Deevey Type I; the survivorship curve for 1991 seeds ofS. shortiiwas closest to Type II. Longevity of 1991 seeds ofS. altissima, 1992 seeds ofS. nemoralisand 1991 and 1992 seeds ofS. shortiiwas <4.0 years, whereas that of 1991 seeds ofS. nemoraliswas <2.3 years; 5% of 1992 seeds ofS. altissimawere viable after 4.0 years.