ROLE OF TEMPERATURE IN THE GERMINATION ECOLOGY OF THE SUMMER ANNUAL BIDENS POLYLEPIS BLAKE (ASTERACEAE)

Citation
Cc. Baskin et al., ROLE OF TEMPERATURE IN THE GERMINATION ECOLOGY OF THE SUMMER ANNUAL BIDENS POLYLEPIS BLAKE (ASTERACEAE), Bulletin of the Torrey Botanical Club, 122(4), 1995, pp. 275-281
Citations number
26
Categorie Soggetti
Plant Sciences
ISSN journal
00409618
Volume
122
Issue
4
Year of publication
1995
Pages
275 - 281
Database
ISI
SICI code
0040-9618(1995)122:4<275:ROTITG>2.0.ZU;2-T
Abstract
Achenes (seeds) of Bidens polylepis were dormant at maturity in autumn , and they came out of dormancy while buried in moist soil in a nonhea ted greenhouse during winter or at 5 or 15/6 degrees C for 12 weeks. A s seeds came out of dormancy, they first germinated at 30/15 and 35/20 degrees C in light and at 30/15 degrees C in darkness. With additiona l loss of dormancy, the minimum temperature for germination in light a nd darkness decreased to 15/6 degrees C. Nondormant seeds re-entered d ormancy (secondary dormancy) when (1)kept in the greenhouse during sum mer, (2) subjected sequentially to simulated March-October temperature s in incubators or (3) exposed to 25/15 or 30/15 degrees C for 24 and 12 weeks, respectively. As seeds entered dormancy, they first lost the ability to germinate at 15/6 degrees C and then at higher temperature s. Buried seeds exposed to seasonal temperature changes for 28 months in the nonheated greenhouse exhibited an annual dormancy/nondormancy c ycle, with full dormancy occurring in September-November. Seeds came o ut of dormancy in winter (December-March), and they germinated to 85-9 6% in light at simulated habitat temperatures from mid-April until Jul y. Although 20-50% of the seeds germinated in darkness at simulated ha bitat temperatures in spring (March-June), only 2% of them germinated while buried in soil in the nonheated greenhouse. Thus, seeds have the potential to form a persistent seed bank.