Download or read book Evolution of Herbicide Resistance in Lolium Perenne Ssp Multiflorum Populations written by Elizabeth Karn and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Herbicide-resistant weeds provide a unique system in which to study the evolution of adaptive traits. The selection pressures, adaptive traits, and often the underlying basis for herbicide resistance are typically known, allowing for studies of adaptive variation across large agricultural landscapes that vary in selection pressures and intensities over space and time. In the last several years, populations of Lolium perenne ssp. multiflorum (Lam.) in orchards and vineyards of northwest California were suspected of evolving resistance to the herbicides glyphosate and glufosinate. Earlier work identified that a non-synonymous mutation in 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene is responsible for glyphosate resistance in the Central Valley of California. The research presented in this dissertation characterizes phenotypes resistant to glyphosate and glufosinate and examines the evolution of glyphosate resistance in northwest California populations of L. perenne ssp. multiflorum using neutral genetic diversity and adaptive genetic variation, to gain a greater understanding of contemporary adaptive evolution across landscapes. In Chapter 1, I measure the frequency of glyphosate-resistant and glufosinate-resistant individuals in 14 populations of L. perenne across three screening times and measure the population-average level of resistance in selected populations. The analysis demonstrates that while both glyphosate- and glufosinate-resistant individuals are present in northwest California with distinct mechanisms conferring resistance to each herbicide, these resistance phenotypes are variable over time, especially for glufosinate. In Chapter 2, using microsatellite genetic variation at 12 loci in the sampled individuals, I show that California L. perenne contains high genetic diversity and admixture across populations, with a potential for spread of glyphosate resistance through gene flow. In Chapter 3, I genotype adaptive genetic variation in the sampled individuals and identified four distinct glyphosate-resistant EPSPS alleles at codon site 106, indicating multiple evolutionary origins of glyphosate resistance in the region, although resistance in some populations cannot be explained by EPSPS mutations at site 106. Together, these results demonstrate that the evolution of adaptive traits across a landscape can be quite complex, with variable phenotypes conferred by multiple independent evolutionary origins of the same adaptive trait with subsequent spread through gene flow.
Download or read book Herbicide Resistance Mechanism s in Italian Ryegrass Lolium Perenne Ssp Multiflorum Populations in the Southern United States written by Reiofeli Algodon Salas and published by . This book was released on 2012 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: Italian ryegrass is a principal weed problem in wheat production fields in the southern US. Resistance to herbicides diclofop, mesosulfuron, and pinoxaden among ryegrass populations has been reported. Glyphosate-resistant Italian ryegrass populations were identified in Desha County, Arkansas. This research aimed to 1) determine resistance patterns to ACCase (diclofop and pinoxaden) and ALS (imazamox, mesosulfuron, and pyroxsulam) herbicides among Italian ryegrass populations from the southern US; 2) determine if cytochrome P450-mediated enhanced herbicide metabolism contributed to resistance; and 3) elucidate the resistance mechanism to glyphosate in four Arkansas populations (Des03, Des05, Des14, and D8). For objective 1, 30 accessions from problematic fields in the southern US between 2008 and 2010 were subjected to dose-response bioassays. Among the 30 accessions, 27 were resistant to both diclofop and mesosulfuron, 25 of which were also resistant to pyroxsulam. Ten Arkansas accessions collected in 2008 were resistant to diclofop, mesosulfuron, pyroxsulam, and imazamox. One accession from Georgia and three accessions from North Carolina were resistant to diclofop, mesosulfuron, pyroxsulam, and pinoxaden. For objective 2, six ryegrass populations with different resistance patterns to glyphosate, ALS- and ACCase herbicides, were treated with P450 inhibitors malathion (1000 g ai ha-1) and 1-aminobenzotriazole (100 microM ABT) before herbicide application. Malathion improved herbicide activity in some populations, but did not completely overcome resistance to any herbicide. This indicates that P450-mediated metabolism is only partially responsible for resistance in these populations. For objective 3, plants from Des03 population were analyzed for resistance level, EPSPS genetic mutation(s), EPSPS enzyme activity, and EPSPS gene copy number. The absorption and translocation of 14C-glyphosate were similar in R and S plants. The EPSPS gene in the R plants did not contain any point mutation(s) associated with glyphosate resistance. Resistance to glyphosate in Des03 is due to increased basal EPSPS enzyme activity resulting from amplification of the EPSPS gene. Follow-up experiments conducted on other glyphosate-R populations, Des05, Des14, and D8, showed 11-fold to 516-fold more copies of the EPSPS gene in resistant plants than their susceptible counterparts indicating that EPSPS gene amplification also confers resistance to glyphosate in these populations.
Download or read book Multiple Herbicide Resistant Weeds and Non target Site Resistance Mechanisms A Global Challenge for Food Production written by Joel Torra and published by Frontiers Media SA. This book was released on 2021-12-20 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Characterization of Herbicide Resistance in Lolium Multiflorum Populations from California and Oregon written by Caio Augusto De Castro Grossi Brunharo and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Italian ryegrass (Lolium multiflorum) is a troublesome weedy species spread throughout the United States, competing for light, water and nutrients with crops. Its control has been chiefly dependent on herbicides due to their effectiveness and practicality. As result of heavy selection pressure, herbicide-resistant populations of Italian ryegrass have been selected in California and Oregon trees and vines. Recently, poor control of Italian ryegrass with paraquat was reported by orchard managers in California, whereas glufosinate-resistant populations were reported in Oregon. We hypothesize that the low paraquat efficacy observed in a California population is due to the selection of a paraquat-resistant biotype. We also hypothesized that non-target-site mechanisms of resistance were selected in glufosinate-resistant Italian ryegrass populations from Oregon. Greenhouse, field and laboratory experiments were carried out to characterize herbicide-resistant Italian ryegrass populations from California. Laboratory experiments were conducted to characterize the resistance to glufosinate in Oregon Italian ryegrass populations. Greenhouse dose-response experiments confirmed the presence of paraquat resistance in an Italian ryegrass population from California, with multiple resistance to clethodim and glyphosate. Glyphosate resistance is due to amino acid substitutions in the EPSPS at position 106. Field experiments with PRE herbicides indicated that tankmixes containing indaziflam and flumioxazin can provide adequate L. multiflorum control up to 150 days after treatment. Resistance to paraquat likely involves vacuolar sequestration of the herbicide. Laboratory experiments with Oregon Italian ryegrass populations indicate that metabolism of glufosinate is involved in the resistance mechanism. These results add generally to the body of knowledge of herbicide resistance in ryegrass and should influence how multiple herbicide-resistant populations are managed in trees and vines of the western US.
Download or read book Herbicide Resistance in Weeds and Crops written by Zvonko Pacanoski and published by BoD – Books on Demand. This book was released on 2017-10-04 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: Herbicides are the dominant technology and the most effective weed control tools ever developed that are used for the control of weeds that infest crops. Over the last several decades, in situations of intense herbicide usage, there have been many examples of the evolution of weed populations resistant to herbicides. Weed adaptations to management tactics, including biochemical mimicry in the form of evolved resistance to the herbicides used for weed control, have increased rapidly throughout agriculture and now threaten global food security. Nowadays, expended space of research activities remains to focus on the herbicide resistance to weeds and crops. The authors of Herbicide Resistance in Weeds and Crops cover various issues regarding the present relevant research.
Download or read book Herbicide Resistance in Weeds Early Detection Mechanisms Dispersal New Insights and Management Issues written by Ilias Travlos and published by Frontiers Media SA. This book was released on 2020-10-28 with total page 329 pages. Available in PDF, EPUB and Kindle. Book excerpt: This eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contact.
Download or read book Measurement and Modelling of Herbicide Resistance Evolution in Lolium Rigidum at Low Rates of Herbicide Application written by Sudheesh Manalil Velayudhan and published by . This book was released on 2010 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: [Truncated abstract] Herbicides help the world to meet its ever-increasing demand for food, fibre and fuel. However, the intensive use of herbicides has led to the evolution of herbicide resistant weeds. Of these resistant weeds, some represent long-term problems in many agro-climatic regions across the world. Lolium rigidum Gaud. (annual ryegrass) is an example of such a major herbicide resistant weed. The cross-pollinating L. rigidum possess many biological and genetic attributes that ensure its success as an ever evolving resistant weed. Besides, there can be operational factors that decide the pace of resistance evolution of which herbicide use rate is a major determinant. Herbicides at the recommended rates ensure high weed mortality. Whenever the same herbicide is used intensively, resistant weed populations evolve often due to the selection of major gene herbicide resistance traits. However, recent laboratory studies indicate the potential of low herbicide rates to result in rapid herbicide resistance evolution in L. rigidum due to the selection of minor gene resistance traits. Until now a crop-field study on whether the reduced herbicide rates that prevail on farms can lead to resistance evolution in L. rigidum, has been lacking. Therefore, this study examined the impact of low rates of diclofop-methyl (ACCase herbicide) on the evolution of herbicide resistance in a herbicide-susceptible L. rigidum population grown either in a field wheat crop or in potted plants maintained in the field. The results established the rapid evolution of diclofop-methyl resistance in both the crop-field and field pot studies in the selected L. rigidum lines. In addition, there was resistance evolution in the selected lines to other herbicides to which the population had never been exposed. For the first time, we demonstrated the potential of a low rates of diclofop-methyl to result in the evolution of diclofop-resistance and cross-resistance in L. rigidum under crop-field conditions. If low rates can result in rapid herbicide resistance by selecting minor herbicide resistance traits in L. rigidum (previous study), is it possible to shift a population towards high level of herbicide susceptibility by excluding minor gene resistance traits? Indeed, such a study will impart better understanding of the low rate herbicide selected resistance traits in the L. rigidum population and hence reconfirms the presence of minor gene resistance traits in L. rigidum population. Therefore, in this study, we attempted to enhance the herbicide susceptibility of an already herbicide susceptible L. rigidum population. This was practically feasible by plant cloning, and spraying one set of cloned L. rigidum plants with low rates of diclofop-methyl. The untreated clone of an individual observed to be highly herbicide-susceptible was selected and bulk-crossed to obtain the susceptible selected seed progeny. Two cycles of selection with low rates of diclofop-methyl resulted in 50% greater diclofop-methyl susceptibility (R:S LD50=0.5) of the twice-selected L. rigidum line. The results of this study are discussed from the perspective of herbicide resistance evolution and its management...
Download or read book Herbicide Resistance in Plants written by Homer M. LeBaron and published by John Wiley & Sons. This book was released on 1982 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Integrated Weed Management for Sustainable Agriculture written by Robert Zimdahl and published by Burleigh Dodds Series in Agric. This book was released on 2017-12-14 with total page 476 pages. Available in PDF, EPUB and Kindle. Book excerpt: Weeds remain a major obstacle to improved yields in agriculture. At the same time, established methods of control are being undermined by problems such as herbicide resistance. This major collection reviews key developments in integrated weed management (IWM) to manage weeds more sustainably.
Download or read book Weed and Crop Resistance to Herbicides written by Rafael de Prado and published by Springer Science & Business Media. This book was released on 1997-05-31 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent decades, repeated use of herbicides in the same field has imposed selection for resistance in species that were formerly susceptible. On the other hand, considerable research in the private and public sectors has been directed towards introducing herbicide tolerance into susceptible crop species. The evolution of herbicide resistance, understanding its mechanisms, characterisation of resistant weed biotypes, development of herbicide-tolerant crops and management of resistant weeds are described throughout the 36 chapters of this book. It has been written by leading researchers based on the contributions made at the International Symposium on Weed and Crop Resistance to Herbicides held at Córdoba, Spain. This book will be a good reference source for research scientists and advanced students.
Download or read book Herbicide Resistance in Plants written by Stephen B. Powles and published by CRC Press. This book was released on 2018-02-01 with total page 365 pages. Available in PDF, EPUB and Kindle. Book excerpt: The late 1980s saw an explosion in the amount and diversity of herbicide resistance, posing a threat to crop production in many countries. The rapid escalation in herbicide resistance worldwide and in the understanding of resistance at the population, biochemical, and molecular level is the focus of this timely book. Leading researchers from North America, Australia, and Western Europe present lucid reviews that consider the population dynamics and genetics, biochemistry, and agro-ecology of resistance. Resistance to various herbicides is discussed in detail, as well as the mechanisms responsible for cross resistance and multiple resistance. This reference is invaluable to those interested in evolution and the ability of species to overcome severe environmental stress.
Download or read book Weed Crop Competition written by Robert L. Zimdahl and published by John Wiley & Sons. This book was released on 2007-11-19 with total page 235 pages. Available in PDF, EPUB and Kindle. Book excerpt: For the past 20 years, the first edition of this text has been widely cited as authoritative academic reference. The latest edition continues the tradition set by the original book, and covers weed science research that has been published since 1980. This book aims to reduce the instance of research duplication—saving scientists and supporting institutions time and money. Not only does the second edition of Weed Crop Competition review, summarize, and combine current research; it critiques the research as well. This text has the potential to accelerate advancements in weed crop competition, which remains an important factor that affects crop yields. Scientists in foreign countries where access to literature is often limited or nonexistent, will find the information in this text invaluable. Weed scientists, crop scientists, plant ecologists, sustainable agriculturists, and organic agriculturists will be well-pleased with this long overdue and much needed new editionWeed Crop Competition provides a unique reference that reviews, summarises and synthesizes the literature published concerning research on this topic. The first edition has been one of the most frequently cited sources in weed science for the past 20 years. The second edition covers the significant body of literature that has been published since 1980. Originally intended to survey existing research, the intent of the book is to reduce the instance of research duplication, thus saving scientists and their institutions time and money, and expediting advancements in weed crop competition, an important factor affecting crop yields. Scientists in foreign countries where access to the literature is often limited or non-existent, find the information an invaluable resource. This long overdue and much needed new edition rejuvenates the tradition set by the original book.
Download or read book A Taxonomic Revision of the Genus Lolium written by Edward E. Terrell and published by . This book was released on 1968 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Triazine Herbicides written by Janis Mc Farland Ph.D. and published by Elsevier. This book was released on 2011-08-19 with total page 604 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past 50 years, triazines have made a great impact on agriculture and world hunger by assisting in the development of new farming methods, providing greater farming and land use capabilities, and increasing crop yields. Triazines are registered in over 80 countries and save billions of dollars a year. The Triazine Herbicides is the one book that presents a comprehensive view of the total science and agriculture of these chemicals. With emphasis on how the chemicals are studied and developed, reviewed, and used at the agricultural level this book provides valuable insight into the benefits of triazine herbicides for sustainable agriculture. - Presents previously unpublished information on the discovery, development and marketing of herbicides - Includes a vital section on the origin, use, economics and fate of triazine herbicides - Covers benefits of triazines in corn and sorghum, sugarcane, citrus, fruit and nut crops - Establishes best management practice and environmental benefits of use in conservation tillage
Download or read book Seed Testing written by Sabry Gobran Elias and published by . This book was released on 2012 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: An essential reference for students, seed technologists, researchers, and seed industry personnel, this comprehensive guide outlines the most widely performed modern seed quality tests, explores the principles behind them, the history of seed testing, why seeds are tested and when, and sampling, sub-sampling, seed laboratory management, accreditation, and seed quality assurance programs. The authors describe statistical applications to seed testing and tolerances, and they provide a detailed morphological and structural description of seed formation and development. The book examines the testing of genetic traits and transgenic seeds, including DNA and protein genetic purity tests, and cultivar purity identification for conventional seeds. In addition to the most common seed purity and viability tests, tests for seed and seedling vigor, seed-borne diseases and seed moisture determination are also discussed.
Download or read book Forage Plant Ecophysiology written by Cory Matthew and published by MDPI. This book was released on 2018-03-16 with total page 221 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a printed edition of the Special Issue "Forage Plant Ecophysiology" that was published in Agriculture
Download or read book Cover Crops for Walnut Orchards written by and published by UCANR Publications. This book was released on 2006 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
