Climatic control of germination in the genus Silene L

Abstract

Background: Seed germination strategies depend on a number of factors such as climatic variables, habitat, life cycle, phylogenetic affiliation and morphological seed traits.

Aims: We present a novel evaluation of the ecological correlates of germination strategies focussing on plant populations drawn from a single genus and considering a number of relevant explanatory variables.

Methods: Temperature and light-controlled germination experiments were carried out on 21 seed accessions belonging to 13 closely related species of the genus Silene L. Accessions were selected to tightly control the phylogenetic effect and give broad ecological and geographic coverage of the genus in Europe, with three North American and Macaronesian outgroups from climatically extreme environments. We used principal component analysis and correlation analyses to identify the correlation structure of germination traits and include multiple explanatory variables.

Results: Three germination strategies were shown to be related to climatic control. (1) Seeds from arid regions with hot, dry summers germinated optimally at cool temperatures associated with the rainfall period under field conditions, whereas (2) the benefit of cold stratification was more marked in provenances characterised by cold, dry winters, and (3) seeds from mild climates preferred warm temperatures for germination. Moreover, (4) biennial populations of disturbed habitats showed synchronised and rapid seed germination over a wide thermal window. In agreement with previous findings, (5) habitat-related syndromes were observed only for wetland populations. Correlations with seed mass were significant when related to summer precipitation, but weak or absent in relation to germination traits, indicating that, though influenced by the local climate, seed mass is a poor predictor of germination strategies.

Conclusions: These results suggest that whilst habitat and life cycle might shape germination patterns to a certain extent, long-term climatic differences play a substantial role in selecting specific germination traits and strategies.

Keywords:

• cold stratification
• light requirement
• principal component analysis
• seed germination
• seed mass
• Silene
• temperature requirement

Acknowledgments

We thank the seed banks of the following institution for the seed material provided, Royal Botanic Gardens, Kew and Botanic Garden Viera y Clavijo, Gran Canaria. We are grateful to Dr Susana Araújo for assistance in statistical analysis. We would like to thank Dr Eduardo Fernández-Pascual for providing useful comments on the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplemental data

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Additional information

Notes on contributors

D. Zani

Deborah Zani’s research focusses on physiological aspects of seed biology.

J. V. Müller

Jonas V. Müller, a senior research leader, is interested in the environmental regulation of seed germination and dormancy.