Access

You are not currently logged in.

Access JSTOR through your library or other institution:

login

Log in through your institution.

If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

Seed Germination Regulation in Bromus tectorum (Poaceae) and Its Ecological Significance

Susan E. Meyer, Phil S. Allen and Julie Beckstead
Oikos
Vol. 78, No. 3 (Apr., 1997), pp. 475-485
Published by: Wiley on behalf of Nordic Society Oikos
DOI: 10.2307/3545609
Stable URL: http://www.jstor.org/stable/3545609
Page Count: 11
  • Read Online (Free)
  • Subscribe ($19.50)
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Seed Germination Regulation in Bromus tectorum (Poaceae) and Its Ecological Significance
Preview not available

Abstract

Bromus tectorum is a winter annual grass that has become extensively naturalized in western North America. Its seeds are usually at least conditionally dormant at dispersal and lose dormancy through dry afterripening. Germination response to temperature for recently harvested seeds and rate of change in germination response during afterripening were examined for collections from 21 western North American populations representing a wide array of habitats. Analysis of variance showed highly significant among-population differences in germination response variables. Principal components analysis of 20 germination variables revealed groups of populations that could be characterized by distinct response syndromes. Degree of dormancy at summer temperatures in recently harvested seeds as well as rate of dormancy loss during dry storage could be related to the risk of premature summer germination in different habitats. Mojave Desert populations showed the most clearly differentiated response. Populations from Intermountain desert and foothill habitats showed intermediate responses and did not form distinct groups. Montane populations showed the widest variation. Fully afterripened seeds from all populations were nondormant and could germinate quickly across a wide temperature range. These results demonstrate the existence of adaptively significant variation in germination response. Such variation probably represents the beginning of genetic differentiation as a result of selection among and within founder populations. Lack of a consistent relationship with habitat reflects the stochastic nature of colonization and the fact that diverse germination strategies may permit persistence, especially in less extreme habitats.

Page Thumbnails

  • Thumbnail: Page 
475
    475
  • Thumbnail: Page 
476
    476
  • Thumbnail: Page 
477
    477
  • Thumbnail: Page 
478
    478
  • Thumbnail: Page 
479
    479
  • Thumbnail: Page 
480
    480
  • Thumbnail: Page 
481
    481
  • Thumbnail: Page 
482
    482
  • Thumbnail: Page 
483
    483
  • Thumbnail: Page 
484
    484
  • Thumbnail: Page 
485
    485