Effect of heat on seed germination and viability in species of Cistaceae

ABSTRACT

Background: Species of the Cistaceae family have hard-coated seeds and consequently require scarification for germination. It is widely assumed that the high temperature caused by fire is a scarifying agent that triggers seed germination in the Cistaceae. However, to date there is insufficient knowledge regarding species, populations and diverse variables associated with germination to consider such a fire trigger generally applicable.

Aims: To test the relationship between exposure to fire and germination in 10 species of the Cistaceae family.

Methods: We quantified after different heat treatments the germination and seed viability in 10 species of Cistus, Fumana, Halimium, Helianthemum and Tuberaria Final germination percentage, t₅₀ and seed viability were determined.

Results: Heat treatment increased germination in all except the species of Helianthemum; however, the rate of increase was dependent on species. Germination speed (t₅₀) was less affected by heat than final germination, and seed viability did not decrease except for H. hirtum.

Conclusions: Most of the species showed high tolerance and a positive response to heat although germination patterns were idiosyncratic of each species. This work evidences the wide range of germination responses to heat within Cistaceae, and consequently the differential role of fire within this plant family.

KEYWORDS:

• Cistus
• fire
• Fumana
• Halimium
• hard seed
• Helianthemum
• physical seed dormancy
• Tuberaria

Acknowledgements

We thank Ángel Velasco, Mª Teresa Álvarez and Marina Robledo for their technical support; Víctor Resco, Laszlo Nagy and two anonymous reviewers for their useful comments and suggestions.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was supported by the University of Castilla-La Mancha.

Notes on contributors

Belén Luna

Belén Luna is a plant ecologist interested in the ecophysiology of seeds and in fire ecology.

Daniel Chamorro

Daniel Chamorro is a post-doctoral researcher in seed ecology.

Beatriz Pérez

Beatriz Pérez is a plant ecologist studying fire ecology.