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A Comparative Study of Germination Ecology of Four Papaver Taxa
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: Annals of Botany, ISSN 0305-7364, Vol. 99, no 5, 935-946 p.Article in journal (Refereed) Published
Abstract [en]

Background and Aims: Comparative studies of closely related taxa can increase understanding of adaptations and changes in seed dormancy and germination preferences in an evolutionary perspective. For such studies, a method to describe and compare the performance of taxa in a general way is needed. The germination ecology of four Papaver taxa was studied with the aim of describing and comparing their responses to different seasonal temperature regimes.

Methods: Germination of Papaver argemone, P. rhoeas, P. dubium ssp. dubium and P. dubium ssp. lecoqii was investigated in three different artificial climates over 2.5 years. Seeds were collected in southern Sweden, and samples from different populations were used as replicates of taxa.

Key Results: Despite substantial intra-taxa variation, there were clear taxon-specific responses. Most germination occurred in the warmest climate. In general, the warmer the climate the more germination occurred in autumn instead of spring. Papaver argemone, phylogenetically most distant from the others, was, in contrast to the other taxa, restricted to germinating only at lower temperatures.

Conclusions: Seed dormancy and germination may be described by dormancy pattern, germination preferences and dormancy strength. The general dormancy pattern was a common feature for these taxa and therefore probably an evolutionary conservative character. Germination preferences varied between taxa, resulting in different temperature optima and intervals for germination, and dormancy strength was to some extent taxon-specific, but highly variable. The dormancy pattern explained how the taxa can perform as winter annuals in warmer climates, but mainly as summer annuals in colder climates. Hence, there is no need to interpret the within-taxon temporal differences in seedling emergence as local adaptations. In the field, an entire seed cohort will not germinate during a single season. Instead, emergence will be distributed over several seasons, regardless of local climate, weather and soil cultivation methods.

Place, publisher, year, edition, pages
Institutionen för fysik, kemi och biologi , 2007. Vol. 99, no 5, 935-946 p.
Keyword [en]
Annual weed, germination ecology, morphophysiological dormancy, Papaver argemone, Papaver dubium, Papaver rhoeas, Papaveraceae, poppy, seed dormancy, Sweden, summer annual, winter annual
National Category
Natural Sciences
URN: urn:nbn:se:liu:diva-11884DOI: 10.1093/aob/mcm045OAI: diva2:18285
The original article is: Laila M. Karlsson and Per Milberg, A Comparative Study of Germination Ecology of Four Papaver Taxa, 2007, Annals of Botany, (99), 935-946. 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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