Download or read book Plant Metabolites under Environmental Stress written by Nivas M. Desai and published by CRC Press. This book was released on 2023-02-01 with total page 333 pages. Available in PDF, EPUB and Kindle. Book excerpt: This new volume provides a timely update on the knowledge of plant responses to various environmental stresses such as salinity, waterlogging, drought, pollution, heat, temperature, oxidative stress, and mineral deficiencies. Chapters focus on physiological and biochemical mechanisms identified in plants that are crucial for them to adapt to biotic and abiotic stress and the methods for improving plant tolerance mechanisms. The book also throws light on plant secondary metabolites such as phenolic compounds and plant growth regulators in ameliorating the stressful conditions in plants. The scientific knowledge and expertise presented in this volume will be valuable to agronomists, plant physiologists, horticulturists, research scholars of botany and agriculture science, and academicians of plant sciences as well as students in these areas.

Download or read book Plant Metabolites and Regulation under Environmental Stress written by Parvaiz Ahmad and published by Academic Press. This book was released on 2018-03-19 with total page 446 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plant Metabolites and Regulation Under Environmental Stress presents the latest research on both primary and secondary metabolites. The book sheds light on the metabolic pathways of primary and secondary metabolites, the role of these metabolites in plants, and the environmental impact on the regulation of these metabolites. Users will find a comprehensive, practical reference that aids researchers in their understanding of the role of plant metabolites in stress tolerance. Highlights new advances in the understanding of plant metabolism Features 17 protocols and methods for analysis of important plant secondary metabolites Includes sections on environmental adaptations and plant metabolites, plant metabolites and breeding, plant microbiome and metabolites, and plant metabolism under non-stress conditions

Download or read book Biology and Biotechnology of Environmental Stress Tolerance in Plants written by Aryadeep Roychoudhury and published by CRC Press. This book was released on 2023-07-21 with total page 741 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abiotic stresses such as drought, high salt, cold, heat, UV radiation, heavy metal pollution, etc., are increasingly responsible for restricting plant growth and agricultural production and are becoming more alarming due to threats from global climate change. To combat these threats, this new 3-volume set provides a comprehensive understanding of the mechanisms that mediate biosynthesis, accumulation, and degradation of plant metabolites to improve crop production and enhance abiotic stress tolerance in plants. Volume 1: Secondary Metabolites in Environmental Stress Tolerance focuses exclusively on the diverse secondary metabolites that play a major role in the adaptation of plants to the environment and in overcoming stress conditions as well as their implications in enhancing tolerance mechanisms. The book presents information on the protective roles rendered by a wide array of antioxidative secondary metabolites and their regulation during diverse environmental stress. Volume 2: Trace Elements in Environmental Stress Tolerance throws light on the different inorganic trace elements, including metal nanoparticles, that help to deal with various environmental stresses. While these elements at high level create considerable phytotoxicity and halt metabolic and enzymatic activity, they also promote growth and development in limited quantity, so that they have significant potential in revamping plant morphology and physiology under stressed conditions. Hence, optimum concentration management of these elements can help to mitigate world hunger and contribute toward sustainable agriculture and food security under challenging environments. Volume 3: Sustainable Approaches for Enhancing Environmental Stress Tolerance focuses on agronomic and biochemical approaches as well as biotechnological and high-throughput technologies, including the prospects of genetic engineering, epigenetics and the latest CRISPR/Cas technology in generating stress-tolerant plants. The volume provides a clear roadmap for the implementation of techniques for improving abiotic stress tolerance in plants for better sustenance.

Download or read book Biology and Biotechnology of Environmental Stress Tolerance in Plants written by Aryadeep Roychoudhury and published by CRC Press. This book was released on 2023-07-21 with total page 481 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abiotic stresses such as drought, high salt, cold, heat, UV radiation, heavy metal pollution, etc., are increasingly responsible for restricting plant growth and agricultural production and are becoming more alarming due to threats from global climate change. To combat these threats, this new 3-volume set provides a comprehensive understanding of the mechanisms that mediate biosynthesis, accumulation, and degradation of plant metabolites to improve crop production and enhance abiotic stress tolerance in plants. Volume 1: Secondary Metabolites in Environmental Stress Tolerance focuses exclusively on the diverse secondary metabolites that play a major role in the adaptation of plants to the environment and in overcoming stress conditions as well as their implications for enhancing tolerance mechanisms. The book presents available information on the protective roles rendered by a wide array of antioxidative secondary metabolites and their regulation during diverse environmental stress. Volume 2: Trace Elements in Environmental Stress Tolerance throws light on the different inorganic trace elements, including metal nanoparticles, that help to deal with environmental stresses. While these elements at high level create considerable phytotoxicity and halt metabolic and enzymatic activity, they also promote growth and development in limited quantity, so that they have significant potential in revamping plant morphology and physiology under stressed conditions. Hence, optimum concentration management of these elements can help to mitigate world hunger and contribute toward sustainable agriculture and food security under challenging environments. Volume 3: Sustainable Approaches for Enhancing Environmental Stress Tolerance focuses on the agronomic and biochemical approaches as well as biotechnological and high-throughput technologies, including the prospects of genetic engineering, epigenetics and the latest CRISPR/Cas technology, in generating stress-tolerant plants. The volume provides a clear roadmap for the implementation of techniques for improving abiotic stress tolerance in plants for better sustenance.

Download or read book Plant Performance Under Environmental Stress written by Azamal Husen and published by Springer Nature. This book was released on 2021-08-23 with total page 604 pages. Available in PDF, EPUB and Kindle. Book excerpt: Global climate change is bound to create a number of abiotic and biotic stresses in the environment, which would affect the overall growth and productivity of plants. Like other living beings, plants have the ability to protect themselves by evolving various mechanisms against stresses, despite being sessile in nature. They manage to withstand extremes of temperature, drought, flooding, salinity, heavy metals, atmospheric pollution, toxic chemicals and a variety of living organisms, especially viruses, bacteria, fungi, nematodes, insects and arachnids and weeds. Incidence of abiotic stresses may alter the plant-pest interactions by enhancing susceptibility of plants to pathogenic organisms. These interactions often change plant response to abiotic stresses. Plant growth regulators modulate plant responses to biotic and abiotic stresses, and regulate their growth and developmental cascades. A number of physiological and molecular processes that act together in a complex regulatory network, further manage these responses. Crosstalk between autophagy and hormones also occurs to develop tolerance in plants towards multiple abiotic stresses. Similarly, biostimulants, in combination with correct agronomic practices, have shown beneficial effects on plant metabolism due to the hormonal activity that stimulates different metabolic pathways. At the same time, they reduce the use of agrochemicals and impart tolerance to biotic and abiotic stress. Further, the use of bio- and nano-fertilizers seem to hold promise to improve the nutrient use efficiency and hence the plant yield under stressful environments. It has also been shown that the seed priming agents impart stress tolerance. Additionally, tolerance or resistance to stress may also be induced by using specific chemical compounds such as polyamines, proline, glycine betaine, hydrogen sulfide, silicon, β-aminobutyric acid, γ-aminobutyric acid and so on. This book discusses the advances in plant performance under stressful conditions. It should be very useful to graduate students, researchers, and scientists in the fields of botanical science, crop science, agriculture, horticulture, ecological and environmental science.

Download or read book Environmental Stress Physiology of Plants and Crop Productivity written by Tajinder Kaur and published by Bentham Science Publishers. This book was released on 2021-05-06 with total page 243 pages. Available in PDF, EPUB and Kindle. Book excerpt: The knowledge of plant responses to various abiotic stresses is crucial to understand their underlying mechanisms as well as the methods to develop new varieties of crops, which are better suited to the environment they are grown in. Environmental Stress Physiology of Plants and Crop Productivity provides readers a timely update on the knowledge about plant responses to a variety of stresses such as salinity, temperature, drought, oxidative stress and mineral deficiencies. Chapters focus on biochemical mechanisms identified in plants crucial to adapting to specific abiotic stressors along with the methods of improving plant tolerance. The book also sheds light on plant secondary metabolites such as phenylpropanoids and plant growth regulators in ameliorating the stressful conditions in plants. Additional chapters present an overview of applications of genomics, proteomics and metabolomics (including CRISPR/CAS techniques) to develop abiotic stress tolerant crops. The editors have also provided detailed references for extended reading to support the information in the book. Environmental Stress Physiology of Plants and Crop Productivity is an informative reference for scholars and researchers working in the field of botany, agriculture, crop science and physiology, soil science, and environmental sciences.

Download or read book Plant Secondary Metabolites Volume Three written by Mohammed Wasim Siddiqui and published by CRC Press. This book was released on 2017-01-06 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: This third book in the three-volume Plant Secondary Metabolites examines the relationship between environmental stress and the physiology of plants, leading to stimulation of secondary metabolites. Various stressors are discussed, including plant and soil interfaces, changing climate elements, essential plant nutrients, pest insects, plant pathogens and microrganisms, and more. The chapters, written by experienced experts, also address the diverse utilization of plant-originated secondary metabolites and more.

Download or read book Plant Acclimation to Environmental Stress written by Narendra Tuteja and published by Springer Science & Business Media. This book was released on 2012-12-09 with total page 507 pages. Available in PDF, EPUB and Kindle. Book excerpt: The mechanisms underlying endurance and adaptation to environmental stress factors in plants have long been the focus of intense research. Plants overcome environmental stresses by development of tolerance, resistance or avoidance mechanisms, adjusting to a gradual change in its environment which allows them to maintain performance across a range of adverse environmental conditions. Plant Acclimation to Environmental Stress presents the latest ideas and trends on induced acclimation of plants to environmental stresses under changing environment. Written by experts around the globe, this volume adds new dimensions in the field of plant acclimation to abiotic stress factors. Comprehensive and lavishly illustrated, Plant Acclimation to Environmental Stress is a state-of-the-art guide suited for scholars and researchers working in the field of crop improvement, genetic engineering and abiotic stress tolerance.

Download or read book Biology and Biotechnology of Environmental Stress Tolerance in Plants written by Aryadeep Roychoudhury and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This new 3-volume set provides a comprehensive understanding of the mechanisms that mediate biosynthesis, accumulation, and degradation of plant metabolites so as to employ novel strategies to improve crop production and enhance abiotic stress tolerance in plants. Abiotic stresses such as drought, high salt, cold, heat, UV radiation, heavy metal pollution, etc., are increasingly responsible for restricting plant growth and agricultural production and are becoming more alarming due to threats from global climate change. To combat these threats, it is imperative to study the underlying mechanisms of stress tolerance from diverse metabolites and the biosynthesis pathways for metabolite production to maintain osmotic balance under diverse environmental stresses. This new book set, Biology and Biotechnology of Environmental Stress Tolerance in Plants, provides that understanding. Volume 1: Secondary Metabolites in Environmental Stress Tolerance focuses exclusively on the diverse secondary metabolites that play a major role in the adaptation of plants to the environment and in overcoming stress conditions as well as their implications in enhancing tolerance mechanisms. The chapters in this section review and integrate the currently available information on the protective role rendered by a wide array of antioxidative secondary metabolites and their regulation during diverse environmental stress. Volume 2: Trace Elements in Environmental Stress Tolerance throws light on the different inorganic trace elements, including metal nanoparticles, that help to deal with various environmental stresses. While these elements at high level create considerable phytotoxicity and halt metabolic and enzymatic activity, they also promote growth and development in limited quantity, so that they have significant potential in revamping plant morphology and physiology under stressed conditions. Hence, optimum concentration management of these elements can help to mitigate world hunger and contribute toward sustainable agriculture and food security under challenging environments. Volume 3: Sustainable Approaches for Enhancing Environmental Stress Tolerance focuses on the agronomic and biochemical approaches as well as biotechnological and high-throughput technologies, including the prospects of genetic engineering, epigenetics and the latest CRISPR/Cas technology, in generating stress-tolerant plants. The volume provides a clear road map for the implementation of techniques for improving abiotic stress tolerance in plants for better sustenance"--

Download or read book Abiotic Stress Responses in Plants written by Parvaiz Ahmad and published by Springer Science & Business Media. This book was released on 2011-11-16 with total page 475 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abiotic stress cause changes in soil-plant-atmosphere continuum and is responsible for reduced yield in several major crops. Therefore, the subject of abiotic stress response in plants - metabolism, productivity and sustainability - is gaining considerable significance in the contemporary world. Abiotic stress is an integral part of “climate change,” a complex phenomenon with a wide range of unpredictable impacts on the environment. Prolonged exposure to these abiotic stresses results in altered metabolism and damage to biomolecules. Plants evolve defense mechanisms to tolerate these stresses by upregulation of osmolytes, osmoprotectants, and enzymatic and non-enzymatic antioxidants, etc. This volume deals with abiotic stress-induced morphological and anatomical changes, abberations in metabolism, strategies and approaches to increase salt tolerance, managing the drought stress, sustainable fruit production and postharvest stress treatments, role of glutathione reductase, flavonoids as antioxidants in plants, the role of salicylic acid and trehalose in plants, stress-induced flowering. The role of soil organic matter in mineral nutrition and fatty acid profile in response to heavy metal stress are also dealt with. Proteomic markers for oxidative stress as a new tools for reactive oxygen species and photosynthesis research, abscisic acid signaling in plants are covered with chosen examples. Stress responsive genes and gene products including expressed proteins that are implicated in conferring tolerance to the plant are presented. Thus, this volume would provides the reader with a wide spectrum of information including key references and with a large number of illustrations and tables. Dr. Parvaiz is Assistant Professor in Botany at A.S. College, Srinagar, Jammu and Kashmir, India. He has completed his post-graduation in Botany in 2000 from Jamia Hamdard New Delhi India. After his Ph.D from the Indian Institute of Technology (IIT) Delhi, India in 2007 he joined the International Centre for Genetic Engineering and Biotechnology, New Delhi. He has published more than 20 research papers in peer reviewed journals and 4 book chapters. He has also edited a volume which is in press with Studium Press Pvt. India Ltd., New Delhi, India. Dr. Parvaiz is actively engaged in studying the molecular and physio-biochemical responses of different plants (mulberry, pea, Indian mustard) under environmental stress. Prof. M.N.V. Prasad is a Professor in the Department of Plant Sciences at the University of Hyderabad, India. He received B.Sc. (1973) and M.Sc. (1975) degrees from Andhra University, India, and the Ph.D. degree (1979) in botany from the University of Lucknow, India. Prasad has published 216 articles in peer reviewed journals and 82 book chapters and conference proceedings in the broad area of environmental botany and heavy metal stress in plants. He is the author, co-author, editor, or co-editor for eight books. He is the recipient of Pitamber Pant National Environment Fellowship of 2007 awarded by the Ministry of Environment and Forests, Government of India.

Download or read book Biology and Biotechnology of Environmental Stress Tolerance in Plants Sustainable approaches for enhancing environmental stress conditions written by Aryadeep Roychoudhury and published by Aap/Apple Academic Press. This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This new 3-volume set provides a comprehensive understanding of the mechanisms that mediate biosynthesis, accumulation, and degradation of plant metabolites so as to employ novel strategies to improve crop production and enhance abiotic stress tolerance in plants. Abiotic stresses such as drought, high salt, cold, heat, UV radiation, heavy metal pollution, etc., are increasingly responsible for restricting plant growth and agricultural production and are becoming more alarming due to threats from global climate change. To combat these threats, it is imperative to study the underlying mechanisms of stress tolerance from diverse metabolites and the biosynthesis pathways for metabolite production to maintain osmotic balance under diverse environmental stresses. This new book set, Biology and Biotechnology of Environmental Stress Tolerance in Plants, provides that understanding. Volume 1: Secondary Metabolites in Environmental Stress Tolerance focuses exclusively on the diverse secondary metabolites that play a major role in the adaptation of plants to the environment and in overcoming stress conditions as well as their implications in enhancing tolerance mechanisms. The chapters in this section review and integrate the currently available information on the protective role rendered by a wide array of antioxidative secondary metabolites and their regulation during diverse environmental stress. Volume 2: Trace Elements in Environmental Stress Tolerance throws light on the different inorganic trace elements, including metal nanoparticles, that help to deal with various environmental stresses. While these elements at high level create considerable phytotoxicity and halt metabolic and enzymatic activity, they also promote growth and development in limited quantity, so that they have significant potential in revamping plant morphology and physiology under stressed conditions. Hence, optimum concentration management of these elements can help to mitigate world hunger and contribute toward sustainable agriculture and food security under challenging environments. Volume 3: Sustainable Approaches for Enhancing Environmental Stress Tolerance focuses on the agronomic and biochemical approaches as well as biotechnological and high-throughput technologies, including the prospects of genetic engineering, epigenetics and the latest CRISPR/Cas technology, in generating stress-tolerant plants. The volume provides a clear road map for the implementation of techniques for improving abiotic stress tolerance in plants for better sustenance"--

Download or read book Environmental Adaptations and Stress Tolerance of Plants in the Era of Climate Change written by Parvaiz Ahmad and published by Springer Science & Business Media. This book was released on 2011-12-02 with total page 523 pages. Available in PDF, EPUB and Kindle. Book excerpt: Climate change is a complex phenomenon with a wide range of impacts on the environment. Biotic and abiotic stress are a result of climate change. Abiotic stress is caused by primary and secondary stresses which are an impediment to plant productivity. Prolonged exposure to these stresses results in altered metabolism and damage to biomolecules. Plants evolve defense mechanisms to withstand these stresses, e.g. synthesis of osmolytes, osmoprotectants, and antioxidants. Stress responsive genes and gene products including expressed proteins are implicated in conferring tolerance to the plant. This volume will provide the reader with a wide spectrum of information, including vital references. It also provides information as to how phytoconstituents, hormones and plant associated microbes help the plants to tolerate the stress. This volume also highlights the use of plant resources for ameliorating soil contaminants such as heavy metals. Dr. Parvaiz is Assistant professor in Botany at A.S. College, Srinagar, Jammu and Kashmir, India. He has completed his post-graduation in Botany in 2000 from Jamia Hamdard New Delhi India. After his Ph.D from the Indian Institute of Technology (IIT) Delhi, India in 2007 he joined the International Centre for Genetic Engineering and Biotechnology, New Delhi. He has published more than 20 research papers in peer reviewed journals and 4 book chapters. He has also edited a volume which is in press with Studium Press Pvt. India Ltd., New Delhi, India. Dr. Parvaiz is actively engaged in studying the molecular and physio-biochemical responses of different plants (mulberry, pea, Indian mustard) under environmental stress. Prof. M.N.V. Prasad is a Professor in the Department of Plant Sciences at the University of Hyderabad, India. He received B.Sc. (1973) and M.Sc. (1975) degrees from Andhra University, India, and the Ph.D. degree (1979) in botany from the University of Lucknow, India. Prasad had published 216 articles in peer reviewed journals and 82 book chapters and conference proceedings in the broad area of environmental botany and heavy metal stress in plants. He is the author, co-author, editor, or co-editor for eight books. He is the recipient of Pitamber Pant national Environment Fellowship of 2007 awarded by the Ministry of Environment and Forests, Government of India.

Download or read book Plant Environment Interaction written by Mohamed Mahgoub Azooz and published by John Wiley & Sons. This book was released on 2016-01-26 with total page 361 pages. Available in PDF, EPUB and Kindle. Book excerpt: The increase in global population, urbanization and industrialization is resulting in the conversion of cultivated land into wasteland. Providing food from these limited resources to an ever-increasing population is one of the biggest challenges that present agriculturalists and plant scientists are facing. Environmental stresses make this situation even graver. Plants on which mankind is directly or indirectly dependent exhibit various mechanisms for their survival. Adaptability of the plants to changing environment is a matter of concern for plant biologists trying to reach the goal of food security. Despite the induction of several tolerance mechanisms, sensitive plants often fail to withstand these environmental extremes. Using new technological approaches has become essential and imperative. Plant-Environment Interaction: Responses and Approaches to Mitigate Stress throws light on the changing environment and the sustainability of plants under these conditions. It contains the most up-to-date research and comprehensive detailed discussions in plant physiology, climate change, agronomy and forestry, sometimes from a molecular point of view, to convey in-depth understanding of the effects of environmental stress in plants, their responses to the environment, how to mitigate the negative effects and improve yield under stress. This edited volume is written by expert plant biologists from around the world, providing invaluable knowledge to graduate and undergraduate students in plant biochemistry, food chemistry, plant physiology, molecular biology, plant biotechnology, and environmental sciences. This book updates scientists and researchers with the very latest information and sustainable methods used for stress tolerance, which will also be of considerable interest to plant based companies and institutions concerned with the campaign of food security.

Download or read book Mechanisms of Environmental Stress Resistance in Plants written by Amarjit S. Basra and published by Routledge. This book was released on 2022-02-26 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plant growth and productivity are limited in many areas of the world by a wide variety of environmental stresses. This book discusses progress made toward the major goal of uncovering the plant resistance mechanisms to biotic and abiotic stresses; the purpose being to utilise this knowledge in genetic modification of plants for achieving improved stress resistance. This volume achieves a new synthesis in considering the mechanisms of resistance at various levels of organisation -- from individual cells and tissues, through whole plants, to communities. Chapters are written by internationally acknowledged experts, who have a wealth of research and teaching experience. With comprehensive and up-to-date coverage, this book analyses many outstanding problems and poses important questions for future research.

Download or read book Climate Change and Plant Abiotic Stress Tolerance written by Narendra Tuteja and published by Wiley-Blackwell. This book was released on 2014-02-17 with total page 1208 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this ready reference, a global team of experts comprehensively cover molecular and cell biology-based approaches to the impact of increasing global temperatures on crop productivity. The work is divided into four parts. Following an introduction to the general challenges for agriculture around the globe due to climate change, part two discusses how the resulting increase of abiotic stress factors can be dealt with. The third part then outlines the different strategies and approaches to address the challenge of climate change, and the whole is rounded off by a number of specific examples of improvements to crop productivity. With its forward-looking focus on solutions, this book is an indispensable help for the agro-industry, policy makers and academia.

Download or read book Plant Life under Changing Environment written by Durgesh Kumar Tripathi and published by Academic Press. This book was released on 2020-04-10 with total page 1014 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plant Life under Changing Environment: Responses and Management presents the latest insights, reflecting the significant progress that has been made in understanding plant responses to various changing environmental impacts, as well as strategies for alleviating their adverse effects, including abiotic stresses. Growing from a focus on plants and their ability to respond, adapt, and survive, Plant Life under Changing Environment: Responses and Management addresses options for mitigating those responses to ensure maximum health and growth. Researchers and advanced students in environmental sciences, plant ecophysiology, biochemistry, molecular biology, nano-pollution climate change, and soil pollution will find this an important foundational resource. Covers both responses and adaptation of plants to altered environmental states Illustrates the current impact of climate change on plant productivity, along with mitigation strategies Includes transcriptomic, proteomic, metabolomic and ionomic approaches

Download or read book Protective Chemical Agents in the Amelioration of Plant Abiotic Stress written by Aryadeep Roychoudhury and published by John Wiley & Sons. This book was released on 2020-07-07 with total page 698 pages. Available in PDF, EPUB and Kindle. Book excerpt: A guide to the chemical agents that protect plants from various environmental stressors Protective Chemical Agents in the Amelioration of Plant Abiotic Stress offers a guide to the diverse chemical agents that have the potential to mitigate different forms of abiotic stresses in plants. Edited by two experts on the topic, the book explores the role of novel chemicals and shows how using such unique chemical agents can tackle the oxidative damages caused by environmental stresses. Exogenous application of different chemical agents or chemical priming of seeds presents opportunities for crop stress management. The use of chemical compounds as protective agents has been found to improve plant tolerance significantly in various crop and non-crop species against a range of different individually applied abiotic stresses by regulating the endogenous levels of the protective agents within plants. This important book: Explores the efficacy of various chemical agents to eliminate abiotic stress Offers a groundbreaking look at the topic and reviews the most recent advances in the field Includes information from noted authorities on the subject Promises to benefit agriculture under stress conditions at the ground level Written for researchers, academicians, and scientists, Protective Chemical Agents in the Amelioration of Plant Abiotic Stress details the wide range of protective chemical agents, their applications, and their intricate biochemical and molecular mechanism of action within the plant systems during adverse situations.