Principles And Practices In Plant Ecology Allelochemical Interactions

Principles and Practices in Plant Ecology: Allelochemical Interactions provides insights and details recent progress about allelochemical research from the ecosystem standpoint. Research on chemical ecology of allelochemicals in the last three decades has established this field as a mature science that interrelates the research of biologists, weed and crop scientists, agronomists, natural product chemists, microbiologists, ecologists, soil scientists, and plant physiologists and pathologists. This book demonstrates how the influence of allelochemicals on the various components of an ecosystem-including soil microbial ecology, soil nutrients, and physical, chemical, and biological soil factors-may affect growth, distribution, and survival of plant species. Internationally renowned exper†s discuss how a better understanding of allelochemical phenomena can lead to true sustainable agriculture.

Allelochemical interactions, during the last three decades, have evolved as an important branch of plant ecology. In this book, in general, the effects of chemical compounds released from plants (including microorganisms), on other plants in their vicinity are considered under the term "allelopa-thy." The term "allelochemical" is used in a wider context in the field of ecology where it includes, but is not limited to, plant and microorganism interactions. Allelochemicals released from plants (including microorganisms) have multifaceted influences on ecosystems; these also influence soil microbial ecology, soil nutrients, and physical, chemical and biological soil factors. We believe~that it is extraordinarily difficult to separate the influence of allelochemicals on each of these components of an ecosystem. Effects on any one of these components, due to allelochemicals, may influence growth, distribution, and survival of plant species. The aim of this book is to provide insight and recent progress on allelochemical research from this multifaceted standpoint. Research articles-reporting results of substantially completed work, and review articles-presenting novel and critical appraisals of specific topics of interest, are included. Yet it may not be a comprehensive treatise on the subject. The sequence of chapters in the book starts with an overview followed by 34 chapters contributed by scientists around the world, thus presenting a global perspective on allelochemical research. Section I-Methodologies (Chapters 2-8), discusses important aspects of methodology in the study of allelopathy, shortcom-ings of bioassays for allelopathy, bioassays for different plant groups, extraction of allelochemicals from soil, sampling procedures, and an outline of analytical methods for different classes of allelo-chemicals. Section Il-Interactions Among Plant and Microbial Systems (Chapter 945), presents allelochemical research in aquatic and terrestrial ecosystems, and includes other important subjects like pollen allelopathy. Section Ill-Ecological Aspects (Chapters 16-22), illustrates the signifi-cance of ecological studies in allelochemical research, and discusses the important role that the soil environment plays in the functioning of allelochemicals. Section IV-Biochemical, Chemical and Physiological Aspects (Chapters 23-30), discusses biochemical, molecular, and physiological aspects of allelopathy, including information on modes of action of allelochemicals in allelopathy. Allelochemicals have been successfully used in biocontrol of plant pathogens and weeds. This important applied aspect of allelochemistry is discussed under Section V-Biological Control of Plant Disease and Weeds: Applied Aspects (Chapters 31-34). Thus, in totality, the book illustrates the processes, procedures, and applications related to allelochemicals.

Allelochemicals play a great role in managed and natural ecosystems. Apart from plant growth, allelochemicals also may influence nutrient dynamics, mycorrhizae, soil chemical characteristics, and microbial ecology. Synergistic action of various factors may better explain plant growth and distribution in natural systems. The book emphasizes the role of allelochemicals in shaping the structure of plant communities in a broader ecological perspective. The book addresses the following questions: (1) How do allelochemicals influence different components of the ecosystem in terms of shaping community structure? (2) Why is it difficult to demonstrate interference by allelochemicals (i.e., allelopathy) in a natural system in its entirety? Despite a large amount of existing literature on allelopathy, why are ecologists still skeptical about the existence of allelopathy in nature? (3) Why are there only scarce data on aquatic ecosystems? (4) What role do allelochemicals play in microbial ecology?.....

This volume presents detailed descriptions and analyses of the underlying features, issues and suppositions associated with seed and seedling laboratory bioassays presented in a previous volume. It is, however, broader in scope and substance in that the information provided is relevant to all water-soluble compounds released to soil by putative allelopathic living plants and their litter and residues. It is ultimately an attempt to update and expand the practical guidelines for designing laboratory bioassays that have previously been provided in the literature with the hope that the designs of future seed and seedling laboratory bioassays will become more relevant to field systems. Standard references have been included to provide background and additional details. This volume has been written specifically for researchers and their graduate students who are interested in studying plant-plant allelopathic interactions.

This book provides the reader relevant information about actual knowledge about the process of allelopathy, covering all aspects from the molecular to the ecological level. Special relevance is given to the physiological and ecophysiological aspects of allelopathy. Several ecosystems are studied and methodological considerations are taken into account in several different chapters. The book has been written to be useful both for Ph.D. students and for senior researchers, so the chapters include all necessary information to be read by beginners, but they also include a lot of useful information and discussion for the initiated.

In the last decade, enormous progress has been made on the physiology of plant roots, including on a wide range of molecular aspects. Much of that progress has been captured in the chapters of this book. Breakthroughs have been made possible through integration of molecular and whole-plant aspects. The classical boundaries between physiology, biochemistry and molecular biology have vanished. There has been a strong focus on a limited number of model species, including Arabidopsis thaliana. That focus has allowed greater insight into the significance of specific genes for plant development and functioning. However, many species are very different from A. thaliana, in that they are mycorrhizal, develop a symbiosis with N2-fixing microsymbionts, or have other specialised root structures. Also, some have a much greater capacity to resist extreme environments, such as soil acidity, salinity, flooding or heavy-metal toxicities, due to specific adaptations. Research on species other than A. thaliana is therefore pivotal, to develop new knowledge in plant sciences in a comprehensive manner. This fundamental new knowledge can be the basis for important applications in, e.g., agriculture and plant conservation. Although significant progress has been made, much remains to be learnt. It is envisaged that discoveries made in the recent past will likely lead to major breakthroughs in the next decade.

This volume continues the retrospective analyses of Volumes I and II, but goes beyond that in an attempt to understand how phenolic acids are partitioned in seedling-solution and seedling-microbe-soil-sand culture systems and how phenolic acid effects on seedlings may be related to the actual and/or conditional physicochemical properties (e.g., solubility, hydrophobicity, pKa, molecular structure and soil sorption/desorption) of simple phenolic acids. Specifically, it explores the quantitative partitioning (i.e., source-sink relationships) of benzoic and cinnamic acids in cucumber seedling-solution and cucumber seedling-microbe-soil-sand systems and how that partitioning may influence phenolic acid effects on cucumber seedlings. Regressions, correlations and conceptual and hypothetical models are used to achieve these objectives. Cucumber seedlings are used as a surrogate for phenolic acid sensitive herbaceous dicotyledonous weed seedlings. This volume was written specifically for researchers and their students interested in understanding how a range of simple phenolic acids and potentially other putative allelopathic compounds released from living plants and their litter and residues may modify soil chemistry, soil and rhizosphere microbial biology, seedling physiology and seedling growth. In addition, this volume describes the potential relationships, where they may exist, for direct transfer of organic compounds between plants, plant communication and plant-plant allelopathic interactions and addresses the following questions: Can physicochemical properties of phenolic acids be used as tools to help understand the complex behavior of phenolic acids and the ultimate effects of phenolic acids on sensitive seedlings? What insights do laboratory bioassays and the conceptual and hypothetical models of laboratory systems provide us concerning the potential behavior and effects of phenolic acids in field systems? What potential role may phenolic acids play in broadleaf-weed seedling emergence in wheat debris cover crop no-till systems?

In an effort to implement conservation measures farmers have used a variety of production methods, including the use of reduced or zero tillage and cover crops. One benefit of these production methods has been early season weed control. The literature suggests that a variety of mechanisms may be involved, among them the allelopathic effects of phenolic acids. This retrospective analysis addresses the following: How likely are phenolic acid concentrations and environmental conditions in wheat no-till cropping systems for the inhibition of annual broadleaf weed emergence? and Do phenolic acids have a dominant role or are they just one component of a larger promoter/modifier/inhibitor complex? The book covers allelopathic plant-plant interactions, laboratory and field experiments, and future research. It uses a journal format, provides justifications for procedures used, if-then hypotheses, and cons and pros so that readers can reach their own conclusions.