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Seed dormancy pattern and germination preferences of the South African annual Papaver aculeatum
Linköping University, Department of Physics, Chemistry and Biology, Ecology . Linköping University, The Institute of Technology.
Linköping University, Department of Physics, Chemistry and Biology, Ecology . Linköping University, The Institute of Technology.ORCID iD: 0000-0001-6128-1051
2007 (English)In: South African Journal of Botany, ISSN 0254-6299, Vol. 73, no 3, 422-428 p.Article in journal (Refereed) Published
Abstract [en]

Seeds from two populations of Papaver aculeatum, collected in South Africa, were subjected to a series of experiments to investigate their dormancy and germination. Dormancy was weak: fresh seeds germinated to nearly 100% at 20/10 and 25/15°C day/night if provided with light, up to 50% at 15/5, but not at all at 30/20°C. Warm stratification increased germination, both in darkness and at 15/5°C, but did not lead to germination at 30/20°C. Cold stratification reduced germination and limited germination to the cooler temperatures. Alternating cold and warm stratifications showed that the species undergoes dormancy cycles. When subjected to three different artificial annual changing climates, with onset both in summer and autumn, most seed germinated in the first autumn. However, in cooler climates, some germination occurred during spring and the second autumn. The general dormancy pattern; reduction during a warm period and induction during a cold, was similar to that of P. rhoeas, a European species and a wide-spread weed. However, germination temperature preferences differed by P. aculeatum avoiding germination at high temperatures, having substantially weaker dormancy when fresh and having more easily reduced dormancy, compared with P. rhoeas. These differences most likely result in differing temporal pattern of germination in the field.

Place, publisher, year, edition, pages
Institutionen för fysik, kemi och biologi , 2007. Vol. 73, no 3, 422-428 p.
Keyword [en]
Annual weed, bristle poppy, dormancy cycle, morphophysiological dormancy, Papaveraceae, thorny poppy
National Category
Natural Sciences
URN: urn:nbn:se:liu:diva-11885DOI: 10.1016/j.sajb.2007.03.007OAI: diva2:18286
Original publication: Laila M. Karlsson and Per Milberg, Seed dormancy pattern and germination preferences of the South African annual Papaver aculeatum, 2007, South African Journal of Botany, (73), 422-428. Copyright: Elsevier B.V., from: 2008-05-22 Created: 2008-05-22 Last updated: 2014-10-08
In thesis
1. Seed dormancy and germination in an ecological context: comparative studies of annual weeds
Open this publication in new window or tab >>Seed dormancy and germination in an ecological context: comparative studies of annual weeds
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [da]

Germination ecology studies, i.e. studies of interactions between characteristics of the seeds and environmental circumstances, provide understanding of spatial and temporal patterns of emergence of wild species, as weeds in the field. A large number of species have seed dormancy, i.e. seeds respond to circumstances not directly evoking germination. Thus, germination may occur only if specific environmental events have occurred in the seeds' past life story, and/or if a suitable time period has passed since ripening on mother plants. In this thesis, three characteristics, i.e. dormancy pattern, germination preferences and dormancy strength, hypothesised as mutually independent seed characteristics, are used to describe dormancy and germination in an ecological context. This conceptual model may be used for descriptions of differences between species, to understand emergence patterns in the field from controlled germination tests, and probably for increasing the understanding of evolution of ecological important properties of seed dormancy and germination.

Fifteen annual weedy taxa were investigated: two groups of temperate climate weeds, Lamium and Papaver, and one group of tropical weeds, co-occurring Asteraceae species of different genera. Intra-species variations in germination occurred for all species, but species-specific germination responses within all groups were revealed in analyses. All species showed some kind of species-specific dormancy pattern that was expressed as increased germination in response to one or more environmental factor not required for the actual germination.

For Lamium and Papaver, the general dormancy pattern was genus-specific. Germination preferences varied slightly within genus. Dormancy strength was to some extent species-specific, but highly variable. The species belonging to Asteraceae showed differences in dormancy pattern. It is shown how such differences can be visualized and compared by plotting response time and achieved germination in two-dimensional graphs, giving species-specific pictures.

Dormancy pattern and germination preferences explained how Papaver can perform as winter annuals in warmer climates, but substantially as summer annuals in colder climates, without local adaptations. For Lamium, the results indicate a local adaptation of increasing dormancy strength: in relatively cold climate in Sweden, a strong dormancy restricted a part of each cohort from germinating during autumn, thus preventing from winter mortality. For the Asteraceae, five of six species clearly responded to cold pretreatment, which is noteworthy considering the small seasonal temperature differences in the study area and in the areas of origin for the species. The six Asteraceae achieved similar emergence timing in the field by responding to different environmental factors.

Together, the results from these fifteen species indicate that dormancy pattern is an evolutionary conservative characteristic, dormancy strength is relatively easily changed, and germination preference is intermediate.

Place, publisher, year, edition, pages
Institutionen för fysik, kemi och biologi, 2007. 56 p.
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1088
Asteraceae, Bidens, Compositae, deadnettle, Galinsoga, germination timing, Guizotia, evolution, Labiatae, Lamiaceae, Lamium, morphophysiological dormancy, Papaveraceae, Papaver, Parthenium, physiological dormancy, poppy, summer annual, Tagetes, Verbesina, winter annual
National Category
Biological Sciences
urn:nbn:se:liu:diva-11444 (URN)978-91-85715-29-9 (ISBN)
Public defence
2007-04-17, Planck, Fysikhuset, Campus Valla, Linköpings universitet, Linköping, 09:30 (English)
Available from: 2008-04-03 Created: 2008-04-03 Last updated: 2014-10-08

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