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.
Journal Article

A Comparative Study of Germination Responses to Diurnally-Fluctuating Temperatures

K. Thompson and J. P. Grime
Journal of Applied Ecology
Vol. 20, No. 1 (Apr., 1983), pp. 141-156
DOI: 10.2307/2403382
Stable URL: http://www.jstor.org/stable/2403382
Page Count: 16
Were these topics helpful?
See somethings inaccurate? Let us know!

Select the topics that are inaccurate.

Cancel
  • Read Online (Free)
  • Download ($18.00)
  • Subscribe ($19.50)
  • Add to My Lists
  • 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.
A Comparative Study of Germination Responses to Diurnally-Fluctuating Temperatures
Preview not available

Abstract

(1) Seeds collected from populations of a range of native herbaceous plants in the Sheffield region were subjected to experimental treatments providing a range of amplitudes of diurnal fluctuations in temperature. All experiments involved a photoperiod of 18 h combined in some species with a comparable series of temperature treatments applied in continuous darkness. (2) In the light a stimulation of germination by fluctuating temperature was observed in forty-six of the 112 species tested. The responses varied from those indicating an absolute requirement in all seeds for large (>5 ⚬C) fluctuations (e.g. Rorippa islandica) to polymorphisms (e.g. Carex otrubae) in which some seeds germinated at constant temperatures whilst the remainder responded to small (<5 ⚬C) fluctuations. (3) The capacity to respond to fluctuating temperatures in the light was prominent in species of wetland where it appears to provide a mechanism whereby spring germination may be initiated by increasing irradiance and falling water table. (4) In certain species (e.g. Ranunculus repens) the effect of continuous darkness was to increase the amplitude of temperature fluctuation necessary for germination. Small-seeded species known to form buried seed reserves (e.g. Juncus effusus) were inhibited by darkness and in the absence of light did not respond to fluctuating temperatures. (5) Sensitivity to temperature fluctuations in darkness was observed in species of grassland, wetland and disturbed habitats, and was conspicuous among species forming persistent seed banks. It seems likely that responses to temperature fluctuations in darkness provide mechanisms of depth-sensing by buried seeds and may initiate establishment from seed within canopy gaps. (6) Many of the species found to respond to temperature fluctuations in darkness are successful weeds of arable land or pasture. A polymorphic response to temperature fluctuations may account partially for the unpredictability of appearance of infestations of these weeds. The ability to invade canopy gaps throughout the year is important to the success of many pasture weeds (e.g. Rumex obtusifolius, Ranunculus repens) and is notably absent from the major sown species, Lolium perenne.

Page Thumbnails

  • Thumbnail: Page 
141
    141
  • Thumbnail: Page 
142
    142
  • Thumbnail: Page 
143
    143
  • Thumbnail: Page 
144
    144
  • Thumbnail: Page 
145
    145
  • Thumbnail: Page 
146
    146
  • Thumbnail: Page 
147
    147
  • Thumbnail: Page 
148
    148
  • Thumbnail: Page 
149
    149
  • Thumbnail: Page 
150
    150
  • Thumbnail: Page 
151
    151
  • Thumbnail: Page 
152
    152
  • Thumbnail: Page 
153
    153
  • Thumbnail: Page 
154
    154
  • Thumbnail: Page 
155
    155
  • Thumbnail: Page 
156
    156
Part of Sustainability