Effect of Stratification Temperature and Germination Temperature on Germination and the Induction of Secondary Dormancy in Common Ragweed Seeds

Willemsen, Roger

doi:10.2307/2442073

Cited by 30 publications

(21 citation statements)

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“…To assess the potential impacts of seed provisioning on seedling growth, 20 seeds (representing four randomly selected mother plants) per population were weighed and no difference in seed weight was observed between infested and uninfested populations ( F 1,6 = 1.40, p > 0.28, nested ANOVA). In early January 2015, seeds of four randomly selected mother plants per population were placed in moist sand and kept at 4°C for 3 months to break dormancy (Willemsen, ). To initiate germination, the seeds were then sown in separate Petri dishes and placed in a climate chamber at 24°C day (14 hr) and 18°C night (10 hr) temperatures.…”

Section: Methodsmentioning

confidence: 99%

Reassociation of an invasive plant with its specialist herbivore provides a test of the shifting defence hypothesis

Wan

Huang

et al. 2018

Journal of Ecology

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The shifting defence hypothesis (SDH) predicts that after invasive plants are introduced to new ranges, they will evolve reduced resistance to specialist herbivores and increased resistance to generalist herbivores because they can escape from specialists but are still attacked by generalists in their nonnative ranges. For this to be true, the subsequent introduction of native specialist herbivores should reverse the above evolutionary processes, but evidence collected so far is scarce. Here, we address this research gap by comparing resistance to specialist and generalist herbivores and resistance‐related traits in the invasive plant Ambrosia artemisiifolia from five populations with about a decade history of infestation by the accidentally introduced native specialist leaf beetle Ophraella communa (infested populations), and three populations without such infestation history (uninfested populations). In common garden experiments, the specialist O. communa performed better on uninfested populations than on infested populations, whereas two generalist insects, Spodoptera litura and Helicoverpa armigera, performed better on infested populations. Chemical analyses showed that plants from infested populations had lower concentrations of chlorogenic acid, an antigeneralist secondary compound that can attract O. communa. Furthermore, across mother plants from all populations studied, chlorogenic acid content was negatively correlated with larval growth of S. litura and positively correlated with that of O. communa. Finally, quantitative defence traits did not differ between infested and uninfested populations. Although our results are most consistent with rapid evolution caused by enemy reassociation, we cannot exclude the possibility that observed differences in resistance result from multiple introductions or selections from other environmental factors. Synthesis. These results suggest that reassociation with a specialist herbivore from the native range may result in a rapid evolution of increased resistance to specialist herbivores and reduced resistance to generalist herbivores in the introduced range, which is likely to be mediated by the reduced production of secondary chemicals that can deter generalists while attracting the introduced specialist. This study supports the shifting defence hypothesis (SDH) from a new viewpoint, emphasizing the importance of incorporating the impacts of both specialist and generalist herbivores when evaluating the long‐term control effects of classical biological control programmes.

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Section: Methodsmentioning

confidence: 99%

Reassociation of an invasive plant with its specialist herbivore provides a test of the shifting defence hypothesis

Wan

Huang

et al. 2018

Journal of Ecology

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“…This is achieved by seeds having primary dormancy at the time of shedding and requiring a period of chilling to break the dormant state. The optimum temperature for breaking dormancy has been determined experimentally as 4°C; slower dormancy release was observed at temperatures above 5°C or below 0°C [23]. In the model, a period of 12 weeks is required at this temperature before seeds are able to germinate.…”

Section: Methodsmentioning

confidence: 99%

“…Sub-optimal temperatures are also effective but take longer. A function describing the rate of dormancy release (d −1 ) at different temperatures based on the results of Willemsen [23] was included in Sirius 2010. Once the threshold for the breaking of dormancy has been reached, the rate of germination was modelled as a Weibull function using hydrothermal time that integrates the effect of temperature and soil moisture (Equation 1):Where Y is cumulative germination (%) at a hydrothermal time ( θ HT ), M is maximum germination, k is rate of increase, a is lag phase and c is shape parameter.…”

Section: Methodsmentioning

confidence: 99%

A Process-Based Approach to Predicting the Effect of Climate Change on the Distribution of an Invasive Allergenic Plant in Europe

et al. 2014

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Ambrosia artemisiifolia is an invasive weed in Europe with highly allergenic pollen. Populations are currently well established and cause significant health problems in the French Rhône valley, Austria, Hungary and Croatia but transient or casual introduced populations are also found in more Northern and Eastern European countries. A process-based model of weed growth, competition and population dynamics was used to predict the future potential for range expansion of A.artemisiifolia under climate change scenarios. The model predicted a northward shift in the available climatic niche for populations to establish and persist, creating a risk of increased health problems in countries including the UK and Denmark. This was accompanied by an increase in relative pollen production at the northern edge of its range. The southern European limit for A.artemisiifolia was not expected to change; populations continued to be limited by drought stress in Spain and Southern Italy. The process-based approach to modelling the impact of climate change on plant populations has the advantage over correlative species distribution models of being able to capture interactions of climate, land use and plant competition at the local scale. However, for this potential to be fully realised, additional empirical data are required on competitive dynamics of A.artemisiifolia in different crops and ruderal plant communities and its capacity to adapt to local conditions.

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“…Germination of A. artemisiifolia occurs only after seeds break dormancy, which should occur at ca. 4 °C (Willemsen 1975). Since Pickett and Baskin (1973) demonstrated higher germination rates with increasing length of stratification, we stored the seeds in a fridge at 4 °C for at least 5 months before starting the experiment.…”

Section: Methodsmentioning

confidence: 99%

Germination and seedling frost tolerance differ between the native and invasive range in common ragweed

2013

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Germination characteristics and frost tolerance of seedlings are crucial parameters for establishment and invasion success of plants. The characterization of differences between populations in native and invasive ranges may improve our understanding of range expansion and adaptation. Here, we investigated germination characteristics of Ambrosia artemisiifolia L., a successful invader in Europe, under a temperature gradient between 5 and 25 °C. Besides rate and speed of germination we determined optimal, minimal and maximal temperature for germination of ten North American and 17 European populations that were sampled along major latitudinal and longitudinal gradients. We furthermore investigated the frost tolerance of seedlings. Germination rate was highest at 15 °C and germination speed was highest at 25 °C. Germination rate, germination speed, frost tolerance of seedlings, and the temperature niche width for germination were significantly higher and broader, respectively, for European populations. This was partly due to a higher seed mass of these populations. Germination traits lacked evidence for adaptation to climatic variables at the point of origin for both provenances. Instead, in the native range, seedling frost tolerance was positively correlated with the risk of frosts which supports the assumption of local adaptation. The increased frost tolerance of European populations may allow germination earlier in the year which may subsequently lead to higher biomass allocation—due to a longer growing period—and result in higher pollen and seed production. The increase in germination rates, germination speed and seedling frost tolerance might result in a higher fitness of the European populations which may facilitate further successful invasion and enhance the existing public health problems associated with this species.Electronic supplementary materialThe online version of this article (doi:10.1007/s00442-013-2813-6) contains supplementary material, which is available to authorized users.

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Effect of Stratification Temperature and Germination Temperature on Germination and the Induction of Secondary Dormancy in Common Ragweed Seeds

Cited by 30 publications

References 0 publications

Reassociation of an invasive plant with its specialist herbivore provides a test of the shifting defence hypothesis

Reassociation of an invasive plant with its specialist herbivore provides a test of the shifting defence hypothesis

A Process-Based Approach to Predicting the Effect of Climate Change on the Distribution of an Invasive Allergenic Plant in Europe

Germination and seedling frost tolerance differ between the native and invasive range in common ragweed

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