Journal Article

Temperature Requirements for Seed Germination and Seedling Development Determine Timing of Seedling Emergence of Three Monocotyledonous Temperate Forest Spring Geophytes

Filip Vandelook and Jozef A. Van Assche

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 102, issue 5, pages 865-875
Published in print November 2008 | ISSN: 0305-7364
Published online August 2008 | e-ISSN: 1095-8290 | DOI: http://dx.doi.org/10.1093/aob/mcn165
Temperature Requirements for Seed Germination and Seedling Development Determine Timing of Seedling Emergence of Three Monocotyledonous Temperate Forest Spring Geophytes

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  • Ecology and Conservation
  • Evolutionary Biology
  • Plant Sciences and Forestry

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Background and Aims

The optimal period for seedling emergence depends on factors such as habitat preference, life cycle and geographical distribution. This research was performed to clarify the role of temperature in regulating processes leading to seedling emergence of the European continental Scilla bifolia and the Atlantic Narcissus pseudonarcissus and Hyacinthoides non-scripta.

Methods

Experiments in natural conditions were performed to examine the phenology of embryo growth, seed germination in the soil and seedling emergence. Effects of temperature conditions on embryo growth, seed germination, seedling growth and leaf formation were studied in temperature-controlled incubators.

Key Results

In nature, embryo growth of all three species was initiated from the moment the seeds were dispersed in spring and continued during summer. A sequence of high temperature followed by a lower temperature was required to complete embryo growth and initiate germination. Seeds of H. non-scripta and N. pseudonarcissus germinated in autumn once they attained the critical E:S ratio, while seeds of S. bifolia started germinating when temperatures were low in winter. Seedlings developed normally, but slowly, only when placed in low temperature conditions (5 or 10 °C), resulting in a time lag between the moment of radicle protrusion and seedling emergence in the field.

Conclusions

A continuous development of the embryo and seedlings of the three species was observed from the moment the seeds were dispersed until seedlings emerged. A sequence of high summer temperatures followed by decreasing autumn and winter temperatures was required for all developmental processes to be completed. Although a time lag occurs between radicle protrusion and seedling emergence, the term ‘epicotyl dormancy’ does not apply here, due to the absence of a period of developmental arrest. Timing of first seedling emergence differed between the three species and could be related to differences in geographical distribution.

Keywords: Hyacinthoides non-scripta; Scilla bifolia; Narcissus pseudonarcissus; germination; E:S ratio; epicotyl dormancy; seedling development; monocotyledon; geophytes

Journal Article.  6852 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

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