Trade-offs between seed dispersal and dormancy in an amphi-basicarpic cold desert annual

Juan J. Lu, Dun Y. Tan, Jerry M. Baskin, Carol C. Baskin

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34 Scopus citations

Abstract

Background and Aims Several studies have demonstrated trade-offs between depth of seed dormancy and dispersal ability for diaspore-dimorphic species. However, relatively little is known about trade-offs between these two life history traits for a species that produces more than two diaspore morphs. The aim of this study was to investigate the relationship between seed dormancy and dispersal in Ceratocarpus arenarius, an amphi-basicarpic cold desert annual that produces a continuum of dispersal unit morphs. Methods A comparison was made of dispersal and dormancy breaking/germination responses of dispersal units from ground level (a), the middle of the plant canopy (c) and the top of the plant canopy (f ). Various features of the morphology and mass of dispersal units and fruits (utricles) were measured. The role of bracteoles in diaspore dispersal by wind, settlement onto the soil surface and dormancy/germination was determined by comparing responses of intact dispersal units and fruits. Movement of dispersal units by wind and animals, seed after-ripening, germination phenology and the presence of water-soluble germination inhibitors in bracteoles were tested using standard procedures. Key Results Dispersal units a, c and f differed in morphology and mass; in the majority of cases, extremes were exhibited by a and f, with c being intermediate. Overall, relative dispersal ability was f . c . a, whereas relative intensity of dormancy was a . c . f. Bracteoles increased dispersal distance by wind, enhanced settlement of diaspores onto the soil surface and mechanically inhibited germination. Conclusions The results provide evidence for a model in which there is a continuous inverse-linear relationship between diaspore dispersal ability and depth of dormancy. Thus, dispersal unit heteromorphism of C. arenarius results in a continuum, from no dispersal ability/high dormancy (dispersal unit a) to high dispersal ability/low dormancy (unit f ), which may be a bet-hedging strategy in the cold desert environment.

Original languageEnglish
Pages (from-to)1815-1827
Number of pages13
JournalAnnals of Botany
Volume112
Issue number9
DOIs
StatePublished - Dec 2013

Bibliographical note

Funding Information:
This work was supported in part by the Scientific Research Program of the Higher Education Institution of Xinjiang, China (FSRPHEXJ 2011S12), the National Natural Science Foundation of China (31160093, U1130301), the Key Program for International S & T Cooperation Projects of China (2010ZR002) and the Early Scientific Research Foundation of Xinjiang Agricultural University of China (XJAU201002).

Keywords

  • Amphi-basicarpic annual
  • Ceratocarpus arenarius
  • Cold desert
  • Conceptual model
  • Diaspore heteromorphism
  • Physiological dormancy
  • Seed dispersal
  • Seed germination.

ASJC Scopus subject areas

  • Plant Science

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