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DOCUMENTATION, CHARACTERIZATION, and PROPOSED MECHANISM of DIQUAT RESISTANCE in Landoltia Punctata (G

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DOCUMENTATION, CHARACTERIZATION, and PROPOSED MECHANISM of DIQUAT RESISTANCE in Landoltia Punctata (G DOCUMENTATION, CHARACTERIZATION, AND PROPOSED MECHANISM OF DIQUAT RESISTANCE IN Landoltia punctata (G. MEYER) D.H. LES AND D.J. CRAWFORD By TYLER J. KOSCHNICK A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2005 Copyright 2005 by Tyler J. Koschnick This document is dedicated to my beloved wife and the expected arrival of our first child, my Dad and Mom (whose successful fight against cancer has given me inspiration and taught me never to give up), family, and friends. ACKNOWLEDGMENTS Over the course of my tenure at the University of Florida, it is hard to acknowledge everyone who assisted and supported my studies. I would first like to thank the person who convinced me to return to academic life, my major professor, Dr. W. T. Haller, for all his advice and guidance. Without his mentoring and support, I do not think I would have ever made it back to school, let alone have finished my degree. I am grateful for a lot of things over the past five years, especially for the friendship outside the “classroom.” I would also like to thank my graduate committee, Drs. L. Glasgow, G. E. MacDonald, W. M. Stall, and D. S. Wofford, for their insight, ideas, and critique. I thank them for tolerating and supporting my ideas and research. Appreciation is also extended to Margaret Glenn for everything that she did to help me throughout my stay in Gainesville. Gratitude is also extended to William Jordan, for numerous days counting duckweed fronds and for keeping my cultures alive. Thanks go to Bob Querns for his assistance in the lab. Special thanks to Dr. Nick Polge for his technical assistance, and to the entire Syngenta Vero Beach Research Center staff for welcoming me into their facilities and allowing me to conduct my radiochem research. Also, I would like to extend a thank you to Syngenta (and Dr. Les Glasgow) for providing 14C-diquat, and technical grade diquat and paraquat for these studies. Appreciation is extended to Eric Cotsenmoyer, and the Lake County Mosquito and Aquatic Plant Management Division, for plant collections and allowing us to work alongside them in their duckweed control efforts. I would also like to acknowledge the iv Aquatic Ecosystem Restoration Foundation for providing the funds to support my research and education. Also thanks go to the Midwest and Florida Aquatic Plant Management Societies Chapters for their support. Finally, I would like to save my most sincere gratitude for my wife and family. I am extremely grateful to my wife for her support, love, friendship, and putting up with me throughout my course of study. Her support was invaluable, and words cannot describe the indebtedness I feel towards her for all her understanding. And finally, I thank my mom and dad for everything they have ever done for me, especially the encouragement, advice, and love. They have always been there to offer advice and support. I thank all my family for believing in me, even when I did not. v TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................................................................................. iv TABLE............................................................................................................................. viii LIST OF FIGURES ........................................................................................................... ix ABSTRACT...................................................................................................................... xii CHAPTER 1 INTRODUCTION ............................................................................................................1 2 VERIFICATION OF LANDOLITA RESISTANCE TO DIQUAT ..............................15 Introduction.................................................................................................................16 Materials and Methods ...............................................................................................18 Formulation .........................................................................................................19 Chlorophyll..........................................................................................................20 Ion Leakage .........................................................................................................20 Results and Discussion ...............................................................................................22 Formulation .........................................................................................................22 Chlorophyll..........................................................................................................23 Ion Leakage .........................................................................................................25 3 ENHANCEMENT OF DIQUAT TOXICITY BY COPPER ON THE RESISTANCE MECHANISM IN LANDOLTIA MEDIATED THROUGH MEMBRANE PERMEABILITY...............................................................................30 Introduction.................................................................................................................31 Materials and Methods ...............................................................................................34 Ion Leakage—Light.............................................................................................34 Ion Leakage—Dark .............................................................................................36 Diuron..................................................................................................................36 Copper and Diquat...............................................................................................37 Copper Formulations—Static..............................................................................37 Copper Formulations—Dip Test .........................................................................38 Results and Discussion ...............................................................................................39 Ion Leakage—Light.............................................................................................39 vi Ion Leakage—Dark .............................................................................................42 Diuron..................................................................................................................45 Copper and Diquat...............................................................................................47 Copper Formulations—Static..............................................................................50 Copper Formulations—Dip.................................................................................51 4 EFFECTS OF COPPER CHELATING AGENTS ON DIQUAT ACTIVITY IN DIQUAT RESISTANT LANDOLTIA ......................................................................58 Introduction.................................................................................................................58 Materials and Methods ...............................................................................................61 Results and Discussion ...............................................................................................64 5 INTERACTIONS BETWEEN CA2+ CHANNEL BLOCKERS AND THE HERBICIDAL ACTIVITY OF DIQUAT ON Landoltia punctata (G. MEYER) D.H. LES AND D.J. CRAWFORD............................................................................70 Introduction.................................................................................................................71 Materials and Methods ...............................................................................................73 Results and Discussion ...............................................................................................76 6 WHOLE PLANT UPTAKE OF 14C-DIQUAT IN DIQUAT RESISTANT AND SUSCEPTIBLE BIOTYPES OF Landoltia punctata (G. MEYER) D.H. LES AND D.J. CRAWFORD.............................................................................................83 Introduction.................................................................................................................84 Materials and Methods ...............................................................................................85 Results and Discussion ...............................................................................................88 LIST OF REFERENCES.................................................................................................101 BIOGRAPHICAL SKETCH ...........................................................................................109 vii TABLE Table page 6.1 The average recovery of 14C-diquat from experiments comparing the uptake of diquat in R and S biotypes of landoltia. ...................................................................88 viii LIST OF FIGURES Figure page 1.1 Line drawing of Landoltia punctata .............................................................................2 2.1 The chlorophyll content of resistant (R) accessions of landoltia after static exposures (48-hr) to two commercial formulations of diquat (Reward QIT and Reward) and technical grade diquat. ........................................................................22 2.2 Dose responses of suspected resistant (R) accessions and susceptible (S) accessions of landoltia to diquat after a 48-hr static exposure.................................23
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