Micronutrients The Borderline Between Their Beneficial Role And Toxicity In Plants

Plants require essential nutrients (macronutrients and micronutrients) for normal functioning. Sufficiency range is the levels of nutrients necessary to meet the plant’s needs for optimal growth. This range depends on individual plant species and the particular nutrient. Nutrient levels outside of a plant’s sufficiency range cause overall crop growth and health to decline, due either to deficiency or toxicity from over-accumulation. Apart from micronutrients (B, Cl, Mn, Fe, Zn, Cu and Mo), Aluminum (Al), cerium (Ce), cobalt (Co), iodine (I), lanthanum (La), sodium (Na), selenium (Se), silicon (Si), titanium (Ti), and vanadium (V) are emerging as novel biostimulants that may enhance crop productivity and nutritional quality. These beneficial elements are not "essential" but when supplied at low dosages, they augment plant growth, development, and yield by stimulating specific molecular, biochemical, and physiological pathways in responses to challenging environments. The book is the first reference volume that approaches plant micronutrient management with the latest biotechnological and omics tools. Expertly curated chapters highlight working solutions as well as open problems and future challenges in plant micronutrient deficiency or toxicity. We believe this book will introduce readers to state-of-the-art developments and research trends in this field.

Large-scale chemical fertilizer application causes irreparable damage to soil structure, mineral cycles, soil microbial flora, plants, and other food chains across ecosystems, culminating in heritable mutations in future generations of consumers. A better way forward is the use of nanofertilizers to focus on macro elements (N, P, K), as switching to nanofertilizers may result in large environmental benefits by replacing the majority of these nutrients. Furthermore, the biosynthesis of nanomaterials using bacteria, algae, yeast, fungus, actinomycetes, and plants has opened up a new avenue of research in the production of inorganic nanoparticles as ecologically friendly fertilizers. Nanofertilizers should also attain increased efficiency because of a several-fold increase in the surface-to-volume ratio of nano-forms of nutrients and their suitability for foliar application, where environmental losses are further reduced. Nanostructured fertilizers can also improve nutrient use efficiency through strategies such as targeted distribution and progressive or controlled-release as they can precisely release their active molecules in response to environmental cues and biological demands. Recent research shows nanofertilizers can increase agricultural productivity by speeding up seed germination, seedling growth, photosynthetic activity, nitrogen metabolism, and carbohydrate and protein synthesis. The potential agricultural benefits of nanofertilizers, their modes of action, and the fate of nanomaterials in soil are all discussed in this book. It also covers nanofertilizer formulation and delivery, applications, uptake, translocation, and their fate in plants, as well as their impact on plant physiology and metabolism. Nutrient nanoformulation is a valuable method that has the potential to alter the agricultural sector and provide solutions to current and future concerns for sustainable and climate-sensitive crops

In all living organisms, essential micronutrients are cofactors of many ubiquitous proteins that participate in crucial metabolic pathways, but can also be toxic when present in excessive concentrations. In order to achieve correct homeostasis, plants need to control uptake of metals from the environment, their distribution to organs and tissues, and their subcellular compartmentalization. They also have to avoid deleterious accumulation of metals and metalloids such as Cd, As and Al. These multiple steps are controlled by their transport across various membrane structures and their storage in different organelles. Thus, integration of these transport systems required for micronutrient trafficking within the plant is necessary for physiological processes to work efficiently. To cope with the variable availability of micronutrients, plants have evolved an intricate collection of physiological and developmental processes, which are under tight control of short- and long-range signaling pathways. Understanding how plants perceive and deal with different micronutrient concentrations, from regulation to active transport, is important to completing the puzzle of plant metal homeostasis. This is an essential area of research, with several implications for plant biology, agriculture and human nutrition. There is a rising interest in developing plants that efficiently mobilize specific metals and prosper in soils with limited micronutrient availability, as well as those that can selectively accumulate beneficial micronutrients in the edible parts while avoiding contaminants such as Cd and As. However, there is still an important gap in our understanding of how nutrients reach the seeds and the relative contribution of each step in the long pathway from the rhizosphere to the seed. Possible rate-limiting steps for micronutrient accumulation in grains should be the primary targets of biotechnological interventions aiming at biofortification. Over the last 10 years, many micronutrient uptake- and transport-related processes have been identified at the molecular and physiological level. The systematic search for mutants and transcriptional responses has allowed analysis of micronutrient-signaling pathways at the cellular level, whereas physiological approaches have been particularly useful in describing micronutrient-signaling processes at the organ and whole-plant level. Large-scale elemental profiling using high-throughput analytical methodologies and their integration with both bioinformatics and genetic tools, along with metal speciation, have been used to decipher the functions of genes that control micronutrients homeostasis. In this research topic, we will follow the pathway of metal movement from the soil to the seed and describe the suggested roles of identified gene products in an effort to understand how plants acquire micronutrients from the soil, how they partition among different tissues and subcellular organelles, and how they regulate their deficiency and overload responses. We also highlight the current work on heavy metals and metalloids uptake and accumulation, the studies on metal selectivity in transporters and the cross-talk between micro and macronutrients. Thus, we believe a continued dialogue and sharing of ideas amongst plant scientists is critical to a better understanding of metal movement into and within the plant.

Geochemistry of micronutrients; geographic distribution of trace element problems; micronutrient adsorption-desorption reactions in soils; inorganic equilibria affecting micronutrients in soils; Chemical forms of micronutrients in soils; organic matter-micronutrients reactions in soil; reactions of metal chelates in soils and nutrient solutions; mechanisms of micronutrient uptake and translocation in plants; function of micronutrients in plants; micronutrients and desease resistance na tolerance in plants; environmental and soil factors affecting micronutrient deficiencies and toxicities; micronutrient soil tests; plant tissue analysis in micronutrients; micronutrient fertilizer technology; fertilizer applications for correcting micronutrient deficiencies; trace elements in animal nutrition; trace elements in human nutrition; beneficial elements, funcional nutrients, and possible new essential elements.

This text presents the principles of mineral nutrition in the light of current advances. For this second edition more emphasis has been placed on root water relations and functions of micronutrients as well as external and internal factors on root growth and the root-soil interface.

This volume is the newest release in the authoritative series issued by the National Academy of Sciences on dietary reference intakes (DRIs). This series provides recommended intakes, such as Recommended Dietary Allowances (RDAs), for use in planning nutritionally adequate diets for individuals based on age and gender. In addition, a new reference intake, the Tolerable Upper Intake Level (UL), has also been established to assist an individual in knowing how much is "too much" of a nutrient. Based on the Institute of Medicine's review of the scientific literature regarding dietary micronutrients, recommendations have been formulated regarding vitamins A and K, iron, iodine, chromium, copper, manganese, molybdenum, zinc, and other potentially beneficial trace elements such as boron to determine the roles, if any, they play in health. The book also: Reviews selected components of food that may influence the bioavailability of these compounds. Develops estimates of dietary intake of these compounds that are compatible with good nutrition throughout the life span and that may decrease risk of chronic disease where data indicate they play a role. Determines Tolerable Upper Intake levels for each nutrient reviewed where adequate scientific data are available in specific population subgroups. Identifies research needed to improve knowledge of the role of these micronutrients in human health. This book will be important to professionals in nutrition research and education.

A deficiency of one or more of the eight plant micronutrients (boron, chlorine, copper, iron, manganese, molybdenum, nickel and zinc) will adversely affect both the yield and quality of crops. Micronutrient deficiencies in crops occur in many parts of the world, at various scales (from one to millions of hectares), but differences in soil conditions, climate, crop genotypes and management, result in marked variations in their occurrence. The causes, effects and alleviation of micronutrient deficiencies in crops in: Australia, India, China, Turkey, the Near East, Africa, Europe, South America and the United States of America, are covered, and these are representative of most of the different conditions under which crops are grown anywhere in the world. Links between low contents of iodine, iron and zinc (human micronutrients) in staple grains and the incidence of human health problems are discussed, together with the ways in which the micronutrient content of food crops can be increased and their bioavailability to humans improved. Detailed treatment of topics, such as: soil types associated with deficiencies, soil testing and plant analysis, field experiments, innovative treatments, micronutrients in the subsoil, nutrient interactions, effects of changing cropping systems, micronutrient budgets and hidden deficiencies in various chapters provides depth to the broad coverage of the book. This book provides a valuable guide to the requirements of crops for plant micronutrients and the causes, occurrence and treatment of deficiencies. It is essential reading for many agronomy, plant nutrition and agricultural extension professionals.