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Loss of desiccation tolerance during germination in neo-tropical pioneer seeds: implications for seed mortality and germination characteristics

Published online by Cambridge University Press:  01 December 2007

Matthew I. Daws*
Affiliation:
School of Biological Sciences, University of Aberdeen, St. Machar Drive, Aberdeen AB24 3UU, UK Seed Conservation Department, Royal Botanic Gardens Kew, Wakehurst Place, Ardingly, West Sussex, RH17 6TNUK
Sheina Bolton
Affiliation:
School of Biological Sciences, University of Aberdeen, St. Machar Drive, Aberdeen AB24 3UU, UK
David F.R.P. Burslem
Affiliation:
School of Biological Sciences, University of Aberdeen, St. Machar Drive, Aberdeen AB24 3UU, UK
Nancy C. Garwood
Affiliation:
Department of Plant Biology, Southern Illinois University, Carbondale, IL 62901-6509, USA
Christopher E. Mullins
Affiliation:
School of Biological Sciences, University of Aberdeen, St. Machar Drive, Aberdeen AB24 3UU, UK
*
*Correspondence Fax: +44(0)1444894110 Email: m.daws@rbgkew.org.uk

Abstract

Orthodox, desiccation-tolerant seeds lose desiccation tolerance during germination. Here, we quantify the timing of the loss of desiccation tolerance, and explore the implications of this event for seed mortality and the shape of germination progress curves for pioneer tree species. For the nine species studied, all seeds in a seedlot lost desiccation tolerance after the same fixed proportion of their time to germination, and this proportion was fairly constant across the species (0.63–0.70). The loss of desiccation tolerance after a fixed proportion of the time to germination has the implication that the maximum number of seeds in a seedlot that can be killed by a single drying event during germination (Mmax) increases with an increasing time to 50% germination (t50) and an increasing slope of the germination progress curve. Consequently, to prevent the seed population from becoming highly vulnerable to desiccation-induced mortality, species with a greater t50 would be expected to have a shallower germination progress curve. In conclusion, these data suggest that the loss of desiccation tolerance during germination may constitute a significant, but previously unexplored, source of mortality for seeds in seasonal environments with unpredictable rainfall.

Type
Research Article
Copyright
Copyright © Cambridge University Press 2007

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Footnotes

Presented at the Fifth International Workshop, Desiccation Tolerance and Sensitivity of Seeds and Vegetative Plant Tissues, Drakensberg, South Africa, 14–21 January 2007.

 

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