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<I>Heterodera Glycines</I> Ichinohe University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Theses, Dissertations, and Student Research in Agronomy and Horticulture Agronomy and Horticulture Department Summer 8-5-2013 MULTIFACTORIAL ANALYSIS OF MORTALITY OF SOYBEAN CYST NEMATODE (Heterodera glycines Ichinohe) POPULATIONS IN SOYBEAN AND IN SOYBEAN FIELDS ANNUALLY ROTATED TO CORN IN NEBRASKA Oscar Perez-Hernandez University of Nebraska-Lincoln Follow this and additional works at: https://digitalcommons.unl.edu/agronhortdiss Part of the Plant Pathology Commons Perez-Hernandez, Oscar, "MULTIFACTORIAL ANALYSIS OF MORTALITY OF SOYBEAN CYST NEMATODE (Heterodera glycines Ichinohe) POPULATIONS IN SOYBEAN AND IN SOYBEAN FIELDS ANNUALLY ROTATED TO CORN IN NEBRASKA" (2013). Theses, Dissertations, and Student Research in Agronomy and Horticulture. 65. https://digitalcommons.unl.edu/agronhortdiss/65 This Article is brought to you for free and open access by the Agronomy and Horticulture Department at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Theses, Dissertations, and Student Research in Agronomy and Horticulture by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. MULTIFACTORIAL ANALYSIS OF MORTALITY OF SOYBEAN CYST NEMATODE (Heterodera glycines Ichinohe) POPULATIONS IN SOYBEAN AND IN SOYBEAN FIELDS ANNUALLY ROTATED TO CORN IN NEBRASKA by Oscar Pérez-Hernández A DISSERTATION Presented to the Faculty of The graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Doctor of Philosophy Major: Agronomy (Plant Pathology) Under the Supervision of Professor Loren J. Giesler Lincoln, Nebraska August, 2013 MULTIFACTORIAL ANALYSIS OF MORTALITY OF SOYBEAN CYST NEMATODE (Heterodera glycines Ichinohe) POPULATIONS IN SOYBEAN AND IN SOYBEAN FIELDS ANNUALLY ROTATED TO CORN IN NEBRASKA Oscar Pérez-Hernández, Ph.D. University of Nebraska, 2013 Advisor: Loren J. Giesler The soybean cyst nematode (SCN; Heterodera glycines Ichinohe) is the most economically important pathogen of soybean in the U.S. The effect of annual corn rotation, soil properties, weather, and agronomic factors on SCN population densities was quantified in 45 fields in Nebraska over three years. SCN population densities (eggs/100 cm3 of soil) in each field were determined before (Pi) and after (Pf) annual corn rotation. Average SCN population density reduction was 50.62%. Multivariate analysis was used to describe the relationship of soil texture (% of sand, silt, and clay), Pi, and Pf. Two principal components explained 92% of the variability in the data set. The first component was represented by texture and accounted for 60.5% and the second was represented by Pi and Pf and explained 31.5%. Cluster analysis identified two groups of fields: one group with predominantly sandy soil (57 to 95%) and the other with predominantly silty soil (23 to 61%). SCN Pi was significantly higher in the sandy group than in the silty group (F = 271.19, P<0.0001). The SCN Pf was modeled using an initial set of eight predictors. A negative binomial regression model with the log link function was applied to a 35-field training data set and a final model was selected. This model was used to estimate the nematode population density after annual corn rotation in the training data set and its prediction power was 82.1%. This predicting capability was confirmed in a validation data set in which the model’s predicting capability was 79.6%. Intra and interplot spatial variability of SCN population densities was analyzed in three experimental areas and its relationship with soybean yield was examined. SCN population densities had an aggregated pattern, showing spatial dependence with those of adjacent plots. The β-binomial distribution adequately described data of incidence and suggested that SCN population density aggregation also occurred within plots. The SCN reproduction factor was not related to the number of SCN-positive cores per plot nor was it related to soybean yield in two soybean varieties assessed, one resistant and one susceptible. iv DEDICATION To Amy, my wife. To my children. To my parents: Felicitas and Miguel. To my brother Nahúm. To all my other relatives and friends to whom a link of love, trust, support, and caring keeps me joined. v ACKNOWLEDGMENTS My gratitude goes first to God for my life, my health, and my family, and to my wife for her love, support, trust, encouragement, and forbearance during this time. A deep appreciation to my advisor, Dr. Loren J. Giesler for the assistantship provided to work in his research program. I thank him for treating me as a friend and for giving the freedom and support to my research ideas and writing. Thanks for his mentoring, feedback, and advice given during the development of this project. Likewise, I thank the members of my Supervisory Committee, Drs. Kenneth Hubbard, Thomas Powers and Stephen Kachman for the help, suggestions and criticisms that contributed to the improvement of this work. Special thanks to Robert J. Prochaska and Tim Brovont for their assistance in this research. In particular, Robert Prochaska was of great help since the beginning of this project and he is also a good friend with whom I shared research ideas and thoughts. I acknowledge my friend Roberto J. Crespo for reviewing the third chapter of this dissertation, and Peter Mullin and Jose Antonio Torres-Vázquez for proofreading the literature review. I also thank Kyle Broderick and Michael Watson for their help in field and laboratory work that this project involved. Likewise, I thank faculty, staff and graduate students in the Departments of Agronomy and Plant Pathology who directly or indirectly contributed to the realization of this project. Especially, I am thankful to Drs. James Steadman, Stephen Wegulo, and to the amicable, kind and helpful staff: Margaret Denning, Joann Ortíz, Deborah Pederson, Mary Joe Haverkamp, Kathy Schindler and Marlene Busse. vi I am grateful to my parents Felicitas and Miguel for their love and encouragement and to my in-laws Victoria Morgan, Sandy and Guy Gillum for their unconditional support to my family during this time. Although I have not included their names in this acknowledgement accounting, I feel profoundly thankful to those individuals who diligently and generously have shared their knowledge and talent with me and others through instructional means. That includes professors, book writers, scientists and non-professional individuals from whom I acquired knowledge that I believe has shaped me as a person and as a researcher. Last but not least, thanks are given to the University of Nebraska-Lincoln for having been the niche of my Doctorate, to the Nebraska Soybean Board for the funds for this research and to Consejo Nacional de Ciencia y Tecnología (CONACYT, National Council of Science and Technology) of México for the economic support provided during the last year of my program. vii TABLE OF CONTENTS ABSTRACT………………………………………………………………………………... ii CHAPTER I. GENERAL INTRODUCTION……………………………………….…….. 1 Dissertation organization……………………………………………………........................................................................................... 1 Introduction……………………………………………………………………………………………………………………………………...….. 2 Literature cited………...……………………………………………………………………………………………...………………………….. 4 CHAPTER II. LITERATURE REVIEW……...…………………………………………... 6 Overview of the components of the soybean cyst nematode pathosystem……………………. 6 The host: soybean (Glycine max)…….…………………………………………………………….……………………...……... 8 Origin, botanical description and taxonomy…………………………………………………...…………… 8 Growth and development…………………………………………………………………………………………………… 9 Genetics and genome.….….………………………...…………………………………………………………………..……… 10 Growing areas in the U.S. and economic importance……….……………...………………………. 12 The pathogen: Heterodera glycines…………………………………………………...…….…………...………………..……. 13 Probable origin and global spread……………..…..……………………………………………………………….... 13 Occurrence and distribution in the U.S. and Nebraska………...………...................……………… 14 Morphology and taxonomy………………...………………………………………………….…………………………... 14 Biology……………………………………………………………………………………………………..………………………………. 16 Life cycle and infection process………………………………………………………………………….… 16 Molecular, genetic and biochemical events of parasitism …………………………... 19 Races and HG types……...…………………………………………………………………………………………… 20 Host range …………...……………………………………………………………………………………………………….. 2 1 Symptoms and damage caused by SCN………………………………………………………………………... 22 Ecology, epidemiology and evolution……………………………………....……………………………………. 22 The environment: the soil…………..………………………………………………………......……………………………………….. 2 4 Soil phases and influence in nematode biology………………………...……………………..……….… 24 Properties known to affect soybean cyst nematode…………………………………………………… 24 Texture……………………………………………………………………………………………………………..….…...…..… 24 pH…………………………………………………………………………..….……………………………………………....…..…. 26 Temperature…………………………………………………………………………..….…........................................…..… 27 Control and management strategies……………………………………………………………………………….……………. 28 Biological and chemical control……………………………...........………………………………..………………… 28 Cultural control……………………………………………………………………………………………………………….……... 29 Resistant varieties………………………………………...…………………………………………………………..… 30 Origin, sources and genetic basis of resistance…………….……….……………….. 30 Crop rotation……………………………………………………………………………………………..………………..... 33 Tillage and irrigation…………….………………………….………………...…………………………………………………
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