Plant Growth Regulators

"Plant growth regulators consist of organic molecules produced synthetically and used to modulate plant growth. There are several classes of plant growth regulators, including auxin, gibberellin, abscisic acid, cytokinins, salicylic, jasmonic acid and ethylene, as well as more recently investigated brassinosteroids, strigolactones, polyamine, etc. These plant growth regulators have either promoting or inhibitory effects on plant growth and development by means of modification in plant secondary metabolism and gene regulation. Some of plant growth regulators may have safe issues in fields. More attention should be paid in the application of plant growth regulators. Researchers also try to find other regulators to do more field experiments, in order to reduce the amount of organic chemicals (e.g., traditional plant growth regulators) used. This book discusses the function, types, uses and safety of plant growth regulators. The effects of plant growth regulators on horticultural plants are specially introduced in this book. Fly ash and soil mycorrhizal fungi-released glomalin also get a lot of attention in this book"--

Agriculture faces many challenges to fulfil the growing demand for sustainable food production and ensure high-quality nutrition for a rapidly growing population. To guarantee adequate food production, it is necessary to increase the yield per area of arable land. A method for achieving this goal has been the application of growth regulators to modulate plant growth. Plant growth regulators (PGRs) are substances in specific formulations which, when applied to plants or seeds, have the capacity to promote, inhibit, or modify physiological traits, development and/or stress responses. They maintain proper balance between source and sink for enhancing crop yield. PGRs are used to maximize productivity and quality, improve consistency in production, and overcome genetic and abiotic limitations to plant productivity. Suitable PGRs include hormones such as cytokinins and auxins, and hormone-like compounds such as mepiquat chloride and paclobutrazol. The use of PGRs in mainstream agriculture has steadily increased within the last 20 years as their benefits have become better understood by growers. Unfortunately, the growth of the PGR market may be constrained by a lack of innovation at a time when an increase in demand for new products will require steady innovation and discovery of novel, cost-competitive, specific, and effective PGRs. A plant bio-stimulant is any substance or microorganism applied to plants with the aim to enhance nutrition efficiency, abiotic stress tolerance and/or crop quality traits, regardless of its nutrients content. Apart from traditional PGRs, which are mostly plant hormones, there are a number of substances/molecules such as nitric oxide, methyl jasmonate, brassinosteroids, seaweed extracts, strigolactones, plant growth promoting rhizobacteria etc. which act as PGRs. These novel PGRs or bio-stimulants have been reported to play important roles in stress responses and adaptation. They can protect plants against various stresses, including water deficit, chilling and high temperatures, salinity and flooding. This book includes chapters ranging from sensing and signalling in plants to translational research. In addition, the cross-talk operative in plants in response to varied signals of biotic and abiotic nature is also presented. Ultimately the objective of this book is to present the current scenario and the future plan of action for the management of stresses through traditional as well as novel PGRs. We believe that this book will initiate and introduce readers to state-of-the-art developments and trends in this field of study.

What are plant growth regulators? In the title, and throughout the text, we have adopted this expression to describe a population of endogenous molecules and synthetic compounds of similar structure that are be lieved to play important roles in the regulation of plant differentiation and development. For many years, plant scientists have endeavoured to understand the nature and action of plant growth regulators and, as a result, an awesome quantity of written material now exists describing these chemicals and their effects. In this book we have aimed to distil this wealth of information into a more digestible form, and in particular we have focused our attention on a critical appraisal of the literature. The past few years have witnessed a change of emphasis in plant growth regulator research, which has been fuelled by powerful new techniques in molecular and cell biology. Today we can do more than just apply a plant growth regulator and quantify its effects; we have reached an exciting crossroads where plant scientists, molecular bio logists and chemists can pool their expertise and apply it to the out standing problems in this area. The combination of these three disciplines within the book is clear evidence of this. In keeping with a volume of this size, we have assumed that the reader has a sound knowledge of plant physiology and biochemistry. However, wherever possible, we have highlighted useful reviews which provide background information, along with recent publications that have contributed significantly to the literature.

As agriculture becomes more mechanized and science increases the possibilities for using inputs to enhance production, the role of PGRs becomes more vital. Plant Growth Regulators in Agriculture and Horticulture provides agriculture professionals and researchers with the information needed to effectively tap these versatile resources to enhance crop production. Through discussions of the “classical five” phytohormones--gibberellins, cytokinins, ethylene, abscisic acid, and auxins--and the growing number of nontraditional PGRs such as oligosaccharins and brassinosteroids, Plant Growth Regulators in Agriculture and Horticulture reviews past and present uses of PGRs in managing crop yield and offers some speculation on future directions. Detailed discussions on the use of PGRs in, for example, grain, ornamental, and citrus crops, introduce readers to strategies for enhancing crop quantity and quality, for improving the postproduction quality of life of perishable plants, and for crop load management, respectively. The book also includes informative visuals, such as tables of common, chemical, and trade names of different commercially available PGRs; diagrams of various PGR processes; as well as before-and-after pictures illustrating the effects of PGRs. Plant Growth Regulators in Agriculture and Horticulture is a comprehensive text covering the role of plant growth regulators in: root formation manipulating yield potential plant stress protection ornamental horticulture postharvest life of ornamentals manipulating fruit development and storage quality citriculture reducing fruit drop bloom-thinning strategies If the history of agriculture, which is over 10,000 years old, was condensed into a twenty-four-hour span, science-based plant breeding would be only about fifteen minutes old. Still, the role of PGRs in agriculture is modest compared to other agrochemicals, such as fungicides, herbicides, and insecticides. Plant Growth Regulators in Agriculture and Horticulture is an invaluable guide to the varied roles filled by PGRs in the attainment of higher-quality, better-yielding crops.

Phytohormones are known to affect the growth and development of plant directly as well as indirectly. Salicylic acid (SA) is a phenolic phytohormone which induces systemic resistance in plants and also regulates defence responses. The derivatives of SA also play an important role in the regulation of various physiological and developmental processes in plants under normal and stressful environmental conditions. SA regulates seed germination, photosynthesis, ethylene biosynthesis, enzyme activities, nutrition, flowering, legume nodulation and overall growth and development of plant. Recently, advancement in elucidating the specific pathways of SA signal transduction has been noticed which helps in understanding the expression of specific genes associated with different developmental programs. The horizon of SA-mediated regulation of various physiological processes has also expanded, and various studies enumerating the efficacy of exogenously applied SA in practical agriculture have also been documented. Therefore, information regarding such recent developments needs to be compiled in the form of a book. This book aims to provide a collective information regarding SA which makes it a versatile plant growth regulator. The chapters included both theoretical and practical aspects that could be of immense use for researches and possible significant developments in future. It is intended that this book will be a help for students, teachers, and researchers, in understanding the relation between the phytohormone and agricultural sciences.

Plant growth regulators consist of organic molecules produced synthetically and used to modulate plant growth. There are several classes of plant growth regulators, including auxin, gibberellin, abscisic acid, cytokinins, salicylic, jasmonic acid and ethylene, as well as more recently investigated brassinosteroids, strigolactones, polyamine, etc. These plant growth regulators have either promoting or inhibitory effects on plant growth and development by means of modification in plant secondary metabolism and gene regulation. Some of plant growth regulators may have safe issues in fields. More attention should be paid in the application of plant growth regulators. Researchers also try to find other regulators to do more field experiments, in order to reduce the amount of organic chemicals (e.g., traditional plant growth regulators) used. This book discusses the function, types, uses and safety of plant growth regulators. The effects of plant growth regulators on horticultural plants are specially introduced in this book. Fly ash and soil mycorrhizal fungi-released glomalin also get a lot of attention in this book.

Plant development, growth and metabolism are highly complex processes requiring the precise fine-tuning of the different molecules involved. Plant growth regulators, also known as plant hormones or phytohormones, are signaling molecules that coordinate these processes, both locally and over greater distance, thereby influencing the growth, development and differentiation of cells, tissues and organs. By compiling open access research papers, the present books reviews the current knowledge on the main plant growth regulators: ABA, auxins, cytokinins, gibberellins, ethylene, brassinosteroids, jasmonic acid, nitric oxide, salicylic acid and strigolactones. In Chapter number 1, the editor presents a detailed overview of strigolactones, the plant growth regulators most recently identified, covering their structure and biosynthesis, signaling and biological functions. The role of ABCG-type ABC transporters in the transport of ABA, cytokinins and strigolactones is discussed in Chapter 2. In Chapter 3, the signaling process of ABA, as well as the role of the PYR/PYL/RCAR receptors, the PP2C phosphatases and the SnRK2 kinases in it, is briefly reviewed. While Chapter 4 exposes the well-known role of this phytohormone in abiotic stress signaling, Chapter 5 describes its function in regulating root length and architecture. In Chapter 6, the response to auxins through the pathways involving TIR1/AFB1, SKP2A, SAUR proteins, IBR5 and MPK12, and ABP1 and TMK1 is discussed. The different families of auxin transporters, as well as their role in monocot development, are reviewed in Chapter 7. Chapter 8 describes how auxin signaling, homeostasis, cross-talk with other phytohormones and interaction with environmental factors controls root hair growth. The homeostasis, signaling and cross-talks of brassinosteroids are described in Chapter 9, while Chapter 10 reviews the biological functions of this phytohormone in rice. Cytokinin signaling and transport are respectively described in Chapters 11 and 12, being a brief overview of the role of this hormone in regulating the architecture of inflorescences presented in Chapter 13. The interaction of ethylene and light signaling to promote hypocotyl growth is described in Chapter 14, while the biological functions of this phytohormone concerning seed dormancy.

Climatic conditions are key determinants of plant growth, whether at the scale of temperature regulation of the cell cycle or at the scale of the geographic limits for a particular species. The climate is changing due to human activities – particularly the emission of greenhouse gases – therefore the conditions for the establishment, growth, reproduction, survival, and distribution of plant species are changing. In contrast to animals, plants are able to cease and resume growth. This flexibility in their architecture and growth pattern is partly achieved by the action of plant hormones. Still, the role of plant growth regulators (PGRs) in agriculture is modest compared to other agrochemicals, such as fungicides, herbicides, and insecticides. Plant Growth Regulators for Climate-Smart Agriculture is an invaluable guide to the varied roles filled by PGRs in the attainment of higher-quality, better-yielding crops. Salient Features (minimum 5): Explores plant growth regulators and anthropogenic climate change. Provides new insights related to hormonal cross-talk in plant development and stress responses. Sheds new light on the role of PGRs in agriculture in the attainment of higher-quality, better-yielding crops. Delivers valuable information on physiological and molecular mechanisms linked to the role of plant growth regulators in stress tolerance. Provides valuable knowledge for students of agronomy, plant physiology, molecular biology, and environmental sciences.