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Root-Zone Glyphosate Exposure Adversely Affects Two Ditch Species
Department of Biological Sciences, University of Memphis, Memphis, TN 38152, USA
* Author to whom correspondence should be addressed.
Received: 11 September 2013; in revised form: 6 December 2013 / Accepted: 10 December 2013 / Published: 18 December 2013
Abstract: Glyphosate, one of the most applied herbicides globally, has been extensively studied for its effects on non-target organisms. In the field, following precipitation, glyphosate runs off into agricultural ditches where it infiltrates into the soil and thus may encounter the roots of vegetation. These edge-of-field ditches share many characteristics with wetlands, including the ability to reduce loads of anthropogenic chemicals through uptake, transformation, and retention. Different species within the ditches may have a differential sensitivity to exposure of the root zone to glyphosate, contributing to patterns of abundance of ruderal species. The present laboratory experiment investigated whether two species commonly found in agricultural ditches in southcentral United States were affected by root zone glyphosate in a dose-dependent manner, with the objective of identifying a sublethal concentration threshold. The root zone of individuals of Polygonum hydropiperoides and Panicum hemitomon were exposed to four concentrations of glyphosate. Leaf chlorophyll content was measured, and the ratio of aboveground biomass to belowground biomass and survival were quantified. The findings from this study showed that root zone glyphosate exposure negatively affected both species including dose-dependent reductions in chlorophyll content. P. hydropiperdoides showed the greatest negative response, with decreased belowground biomass allocation and total mortality at the highest concentrations tested.
Keywords: agricultural runoff; glyphosate; drainage ditches; phytotoxicity; non-target species; wetland plants
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MDPI and ACS Style
Saunders, L.E.; Koontz, M.B.; Pezeshki, R. Root-Zone Glyphosate Exposure Adversely Affects Two Ditch Species. Biology 2013, 2, 1488-1496.
Saunders LE, Koontz MB, Pezeshki R. Root-Zone Glyphosate Exposure Adversely Affects Two Ditch Species. Biology. 2013; 2(4):1488-1496.
Saunders, Lyndsay E.; Koontz, Melissa B.; Pezeshki, Reza. 2013. "Root-Zone Glyphosate Exposure Adversely Affects Two Ditch Species." Biology 2, no. 4: 1488-1496.