Seed Dormancy in Luzula Spicata and L. Parviflora

Abstract

Inhibitors localized at the micropyle and interacting with gibberellin impose dormancy on seeds of both Luzula spicata and L. parviflora from the Colorado Front Range. Removal of the inhibition by precise scarfication elicits germination in both species. Luzula spicata seeds lacking precise scarification were found germinated in tundra soil. Germination was experimentally induced in L. spicata by random scarification, which may be accomplished by repeated freeze—thaw cycles, followed by stratification for 2—3 months. The inhibitor in L. parviflora was inactivated by after—ripening. Germination requirements of L. spicata may represent adaptions to fall freeze—thaw cycles followed by extended chilling under accumulated snow in its tundra habitat. Luzula parviflora, a subalpine and montane species, lacks these adaptations.

Climatic variation and seed persistence: freeze–thaw cycles lower survival via the joint action of abiotic stress and fungal pathogens

“…1a). Our finding that more flaccid, apparently dead, seeds were collected from freeze-thaw treatments than frozen controls suggests that the additive effect of freeze-thaw treatments and fungi arose because freeze-thaw events may compromise seed coat integrity (e.g., Bell and Amen 1970). Physical forces exerted on seeds by proximate soils during freeze-thaw cycles (e.g., expansion, contraction, shearing, heaving) or the nucleation of ice crystals around soil particles or within the seed may fracture or rupture the seed coat and generate avenues of infection for soil pathogens.…”

Seed Survival at Low Temperatures: A Potential Selecting Factor Influencing Community Level Changes in High Altitudes under Climate Change

“…In order to germinate, dormancy must be broken and imbibition take place. Scarification of the seed coat is an important process by which PY seeds become waterpermeable (Baskin et al, 2000;Van Assche et al, 2003) and this can be accomplished by continuous freeze/thaw cycle at the beginning of the growing season (Amen, 1965;Bell and Amen, 1970;Bliss, 1971;Baskin et al, 2000). For example in Luzula spicata, scarification by continuous freeze-thaw cycles early in the spring increases the proportion of germinated seed (Bell and Amen, 1970).…”

“…Scarification of the seed coat is an important process by which PY seeds become waterpermeable (Baskin et al, 2000;Van Assche et al, 2003) and this can be accomplished by continuous freeze/thaw cycle at the beginning of the growing season (Amen, 1965;Bell and Amen, 1970;Bliss, 1971;Baskin et al, 2000). For example in Luzula spicata, scarification by continuous freeze-thaw cycles early in the spring increases the proportion of germinated seed (Bell and Amen, 1970). Further examples illustrating the effects of freeze-thaw cycle alleviating PY in seeds can be found in: Midgley (1926), Busse (1930), Brant et al (1971), Rolston (1978), Pritchard et al (1988), and Shibata et al (1995).…”