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- Title
Greenhouse and laboratory studies on the ecological life cycle of Dalea foliosa (Fabaceae), a federal endangered species
- Authors
Baskin, Carol C.; Baskin, Jerry M.
- Abstract
Certain aspects of the seed and flowering stages of the ecological life cycle of the endangered species Dalea foliosa (Gray) Barneby wereinvestigated under green house and laboratory conditions. Seed dormancy in this species is due to a water impermeable ('hard') seed coat that can be broken completely by mechanical scarification. Nondormantseeds germinated over a wide range of temperatures in both light anddarkness. Soaking in concentrated sulfuric acid for 5 min, dry-heating at 80--100 deg.C for 25--80 min, and dipping in boiling water for 1 min broke dormancy in 52%, 50--77%, and 29%, respectively, of the seeds. Fire caused breakdown of the hard seed coat of seeds on the soil surface, but killed the seeds. Dormancy was not broken by freezing and thawing, soaking in absolute ethanol, or exposing seeds to simulated-summer followed by winter-stratifying temperatures. Seeds sown ina nonheated greenhouse and those in soil samples collected at a population site germinated over a several-year period, mostly in March and April. Thus, the species can form a persistent seed bank. No plantsof D. foliosa flowered under a 10-h daily photoperiod (short day), whereas 100% of those given an 8-h photoperiod plus a 2-h night interruption (long day) flowered. One-hundred percent of the plants kept ina heated greenhouse all winter and 100% of those exposed to winter cold in a nonheated greenhouse flowered. Thus, D. foliosa is an obligate long-day plant that does not require exposure to low temperatures for bud break, shoot growth, or flowering. Management implications ofthis study are discussed.
- Subjects
ENDANGERED species
- Publication
Natural Areas Journal, 1998, Vol 18, Issue 1, p54
- ISSN
0885-8608
- Publication type
Article