Spore germination of eight homosporous ferns in a temperature gradient

https://doi.org/10.1016/j.sajb.2013.04.005Get rights and content
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Highlights

  • Germination of fern spore can be inhibited by sub- and supra-optimal temperatures.

  • Some sub- and supra-optimal temperatures possibly also develop secondary dormancy.

  • These temperatures may be more related to the microhabitat than to the habitat.

  • Diverse spore response to temperature may form a functionally diverse soil bank.

  • A functional diverse spore bank may be prepared to respond to a changing environment.

Abstract

Temperature determines the germination percentage and germination rate of non-dormant fern spores and is known to be a crucial factor for breaking or inducing dormancy in seeds. The objective of this study was to determine the effect of optimal, supraoptimal and suboptimal temperatures on spore germination of eight species of terrestrial homosporous ferns. Spores were incubated for one month in a temperature gradient from 15 to 35 °C in either light or dark. Thereafter, the spores were transferred to 25 °C and incubated in the light. The optimal temperature for germination varied among species, and germination inhibition and possible secondary dormancy were induced at both suboptimal and supraoptimal temperatures. At 35 or 30 °C, with light, spores of most species did not germinate or exhibited low germination percentages, owing to thermoinhibition or possible thermodormancy. In the dark, the spores did not germinate at any of the temperatures tested. After the spores were transferred to the light at 25 °C, a high percentage of spore germination was observed. Incubation in the dark at different temperatures also promoted high germination or dormancy. Temperatures that promoted germination might be related to the season that the different species germinate rather than their habitat, as a number of species within the same habitat had different optimum temperature requirements. Differences in temperature requirements may help to form a soil spore bank. It is necessary to determine whether secondary dormancy was induced by supraoptimal and suboptimal temperatures to further understand spore germination and colonisation in the field.

Keywords

Argyrochosma
Blechnum
Dennstaedtia
Hemionitis
Plagiogyria
Secondary dormancy
Polystichum
Thelypteris

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