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United States Department of Agriculture

Agricultural Research Service

Research Project: GLOBAL CHANGE IN SEMI-ARID RANGELANDS: ECOSYSTEM RESPONSES AND MANAGEMENT ADAPTATIONS

Location: Rangeland Resources Research

Title: Interactive effects of simulated nitrogen deposition and altered precipitation patterns on plant allelochemical concentrations

Authors
item Jamieson, Mary -
item Quintero, Carolina -
item Blumenthal, Dana

Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 4, 2013
Publication Date: September 6, 2013
Citation: Jamieson, M.A., Quintero, C., Blumenthal, D.M. 2013. Interactive effects of simulated nitrogen deposition and altered precipitation patterns on plant allelochemical concentrations. Journal of Chemical Ecology. 39:1204-1208.

Interpretive Summary: Global environmental change alters the supply of multiple limiting resources, such as water and nitrogen, which in turn alters plant growth and production of defenses. While many studies focus on individual global change factors, less is known about how simultaneous changes in abiotic factors influence plant defenses. In this study, we examined the effects of simulated nitrogen deposition and altered precipitation patterns on concentrations of a class of defensive chemical, iridoid glycosides in the invasive plant Dalmatian toadflax. Results indicated that soil water and nitrogen availability interact to shape Dalmatian toadflax defenses. Nitrogen deposition decreased iridoid glycoside concentrations by approximately 25% under reduced water availability, increased concentrations by nearly 37% in control water plots, and had no effect on these chemical defenses for plants growing under augmented water supply. This study demonstrates the importance of examining the influence of multiple abiotic factors on plant chemical defenses in order to predict responses to global environmental change.

Technical Abstract: Global environmental change alters the supply of multiple limiting resources, such as water and nitrogen, which regulate plant primary and secondary metabolism. While many studies focus on individual global change factors, simultaneous changes in abiotic factors may interact to influence plant allelochemical concentrations, and consequently species interactions that are mediated by these chemical constituents. In this study, we examined the individual and interactive effects of simulated nitrogen deposition and altered precipitation patterns on iridoid glycoside concentrations of the invasive plant Linaria dalmatica. Plants were grown from seed for two years under field conditions in a mixed-grass prairie habitat, with nitrogen and water treatments occurring in each growing season over this period. Results indicated that soil water and nitrogen availability interact to shape plant defenses in L. dalmatica. Simulated nitrogen deposition decreased iridoid glycoside concentrations by approximately 25% under reduced water availability, increased concentrations by nearly 37% in control water plots, and had no effect on these chemical defenses for plants growing under augmented water supply. These results suggest differing patterns of allelochemical response, with respect to both the magnitude and direction of change, depending on changes in growing season precipitation patterns. Our study demonstrates the importance of examining the influence of multiple abiotic factors on plant chemical defenses in order to predict responses to global environmental change.

Last Modified: 10/1/2014
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