Survival of experimentally buried large, winged seeds from open sandy habitats defies the established theory of relatedness between seed size, shape, and longevity

Abstract

Accumulated evidence indicates that species with small, rounded seeds predominantly maintain a persistent soil seed bank, while those having larger and less isodiametric seeds have a transient seed bank. We assumed that species in certain special habitats may be exceptions to this rule. In habitats with sandy soil and open vegetation, the seeds do not necessarily have to penetrate the deeper soil layers through cracks in the soil. Instead, the seeds can become buried by a windblown layer of sand, thus seed morphology does not really affect the burial process. To test our hypothesis, we selected five semi-desert shrubs and one perennial herb of open sandy grasslands, all of which had large and flattened seeds. For each species, 12 repetitions of 50 seeds were buried in the soil. Seeds were recovered after 3, 20 and 26 months of burial and subjected to germination tests. Seeds of each species germinated in all test occasions, with final germination as follows: Atriplex canescens 89.0%, Haloxylon ammodendron 11.5%, H. persicum 11.5%, Pteropyrum aucheri 43.5%, Xylosalsola richteri 12.0% and Asclepias syriaca 26.0%. The results confirm the hypothesis that each of the six species is capable of forming a persistent soil seed bank. The results also show that in habitats where seed burial can take place passively through windblown soil, plant species might bypass the tradeoff between seed size/shape and seed longevity.

Keywords:

• Asclepias syriaca
• Atriplex canescens
• germination test
• Haloxylon ammodendron
• Haloxylon persicum
• Iran
• Khorasan
• Pteropyrum aucheri
• persistent seed bank
• Xylosalsola richteri

Acknowledgements

This work was conducted as part of the Ph.D. dissertation of the first author and supported by Grant Number 3/49483 from the office of the Vice-President for Research and Technology of Ferdowsi University of Mashhad. Many thanks are due to Tibor Kalapos and Tamás Weidinger (L. Eötvös University, Budapest), and László Lőkös (Hungarian Natural History Museum, Budapest) for consultations during manuscript preparation.

Authors’ contributions

M. Bahadoran, H. Ejtehadi, and P. Csontos conceived the ideas and designed methodology; M. Bahadoran, H. Ejtehadi, and F. Memariani carried out the experiments and collected the data; M. Bahadoran, J. Tamás and P. Csontos analyzed the data; P. Csontos led the writing of the manuscript. All authors contributed critically to the drafts and gave final approval for publication.

Disclosure statement

The Authors declare that there are no conflicts of interest regarding the publication of this manuscript.

Data availability statement

Data are available in the Appendix of the manuscript.