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Lesson Outline Overview and Objectives Introduction Membrane Review Passive Absorption — Some General Concepts Passive Absorption — Looking at Effects of Charge Passive Absorption — Ion Trapping and Accumulation Benefits of Accumulation via Ion Trapping Passive Absorption — Additional Accumulation Mechanisms Passive Absorption Summary Active Absorption — General Concepts Active Absorption — Three Herbicide Examples Active Absorption Summary Lesson Summary Lesson Media Objects Herbicide Uptake by Leaves and Cells Ionization, pH, and pKa processes

Cellular Absorption of Herbicides Rate Me 1 2 3 4 5 Active Absorption Summary In summary, examples for active absorption of herbicides across plant membranes are limited.  Evidence accumulated to date supports the transport of the cationic herbicide, paraquat, and the anionic herbicides, 2,4-D and glyphosate. In each example, the herbicide appears to be transported by a carrier that recognizes herbicide molecules with structures similar to the endogenous molecules transported by that carrier. The overall importance of active transport to phytotoxicity and herbicide effectiveness is unknown. Thinking Question: Why are there so few herbicides that require active transport to enter a plant cell? Comments Be the first to write a comment... Add Comment

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This project was supported in part by the National Research Initiative Competitive Grants CAP project 2011-68002-30029 from the USDA National Institute of Food and Agriculture, adminstered by the University of California-Davis and by the National Science Foundation (NSF), Division of Undergraduate Education, National SMETE Digital Library Program, Award #0938034, administered by the University of Nebraska. Any opinions, findings, conclusions or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of the USDA or NSF.
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