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United States Department of Agriculture

Agricultural Research Service

Research Project: ECOLOGY, MANAGEMENT AND ENVIRONMENTAL IMPACT OF WEEDY AND INVASIVE PLANT SPECIES IN A CHANGING CLIMATE

Location: Global Change and Photosynthesis Research Unit

Title: Seed coat thickness data clarifies seed size-seed persistence tradeoffs in Abutilon theophrasti (Malvaceae)

Authors
item Schutte, Brian -
item Davis, Adam
item Peinado, S -
item Ashigh, J -

Submitted to: Seed Science Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 4, 2014
Publication Date: May 7, 2014
Citation: Schutte, B.J., Davis, A.S., Peinado, S.A., Ashigh, J. 2014. Seed coat thickness data clarifies seed size-seed persistence tradeoffs in Abutilon theophrasti (Malvaceae). Seed Science Research. 24:119-131.

Interpretive Summary: Weed seed survival in agricultural soils is the primary cause of recurring weed infestations in production fields. Better understanding of the mechanisms of seed defense and persistence within the soil seedbank will aid the development of weed management tactics targeted at decreasing weed seed survival. Previous studies of the relationship between seed size and persistence in the soil seedbank have proved inconclusive. In this study, we expand the seed size-persistence framework to include a defense trait previously correlated with seed survival in soil: seed coat thickness. Using velvetleaf (Abutilon theophrasti) accessions with varied evolutionary histories, we quantified associations among seed traits including morphology, size, coat thickness, dormancy and burial fate. We found that seed lots characterized by smaller seeds with proportionally thicker seed coats were more dormant and more persistent in soil than seed lots characterized by larger seeds with proportionally thinner seed coats. In future studies, we will extend the use of the expanded seed size-persistence-defense framework to other weed species, in order to develop a more comprehensive knowledge of how these traits vary across weed communities.

Technical Abstract: Theoretical models predict that seed size and seedbank persistence evolve interdependently such that strong selection for one trait corresponds with weak selection for the other. This framework is supported by empirical data but conclusive evidence is lacking. In this study, we expand the seed size-persistence framework to include a defense trait previously correlated with seed survival in soil: seed coat thickness. Using Abutilon theophrasti accessions with varied evolutionary histories, we quantified associations among seed traits including morphology, size, coat thickness, dormancy and burial fate. Statistical models were developed to test the hypothesis that combined measurements of seed coat thickness and seed size better explain variability in seedbank persistence (percentage of viable seeds remaining after 1 yr of burial) and seed dormancy (percentage of viable seeds that fail to germinate under optimum conditions) than seed size data alone. Individual seed length, width and mass were negatively correlated with coat proportion (coat thickness relative to seed width and seed mass). Seed lots characterized by smaller seeds with proportionally thicker seed coats were more dormant and more persistent in soil than seed lots characterized by larger seeds with proportionally thinner seed coats. Coat proportion data improved explanatory power of logistic regression models for dormancy and persistence responses to increasing seed size. These results suggest that supplementing seed size data with seed defense data may clarify previously reported contradictory results regarding tradeoffs between seed size and seedbank persistence.

Last Modified: 9/20/2014
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