Nutrient deficiency

Calcium. Soil minerals are a main source of calcium for plants, thus nutrient deficiency of this element in plants is rare. Calcium, in the form of pulverized limestone [1317-65-3] or dolomite [17069-72-6] frequendy is appHed to acidic soils to counteract the acidity and thus improve crop growth. Such liming incidentally ensures an adequate supply of available calcium for plant nutrition. Although pH correction is important for agriculture, and liming agents often are sold by fertilizer distributors, this function is not one of fertilizer manufacture. 

Phosphorus Disorders. Phosphoms nutrient deficiency can lead to rickets, osteomalacia, and osteoporosis, whereas an excess can produce hypocalcemia. Faulty utilisation of phosphoms results in rickets, osteomalacia, osteoporosis, and Paget s disease, and renal or vitamin D-resistant rickets. 

Sulfur Disorders. Sulfur nutrient deficiency results in retarded growth, and faulty utilization in homocystinuria. 

For many years, there has been concern by medical professionals and nutritionists over the effects of dietary sugar on human health. Sucrose has been imphcated as a cause of juvenile hyperactivity, tooth decay, diabetes meUitus, obesity, atherosclerosis, hypoglycemia, and nutrient deficiencies. 

Plants may be affected by indirect modifications of the environment. Soil acidification, for example, can cause the leaching of nutrients, and the release of toxic aluminum. These effects may operate together to produce nutrient deficiencies or imbalances to plants. High soil concentrations of aluminum may prevent uptake and utilization of nutrients by plants.Increased availability of aluminum in soils has been implicated as a cause of forest declines in both Europe and the United States, possibly through the toxic effects on small feeder roots 14),... 

Globally, undernutrition is widespread, leading to impaired growth, defective immune systems, and reduced work capacity. By contrast, in developed countries, there is often excessive food consumption (especially of fat), leading to obesity and to the development of cardiovascular disease and some forms of cancer. Deficiencies of vitamin A, iron, and iodine pose major health concerns in many countries, and deficiencies of other vitamins and minerals are a major cause of iU health. In developed countries, nutrient deficiency is rare, though there are vulnerable sections of the population at risk. Intakes of minerals and vitamins that are adequate to prevent deficiency may be inadequate to promote optimum health and longevity. 

N. Chishaki and T. Horiguchi, Re.sponses of secondary metabolism in plants to nutrient deficiency. Soil Sci. Plant Nutr. 43 981 (1997). 

Nutrient availability also plays a major role in exudation, with deficiencies in N, P, or K often increasing the rate of exudation (218). It is believed that nutrient deficiency may trigger the release of substances such as organic acids or nonproteinogenic amino acids (phytosiderophores), which may enhance the acquisition of the limiting nutrient (219,220). An example here might be the release of phenolic acids such as caffeic acid in response to iron deficiency, which results in an increase in uptake of the cation (221). 

What the UDC-GV model has shown is that plants grown in nutrient-limited conditions could downregulate their growth rate in response to nutrient deficiency and still produce predictions that validate the model at least as well as the original analysis. It is extremely unlikely that the very simple and direct... 

Nutrient deficiencies may also influence the production of allelochemics. The compounds studied in great detail have been the phenolic compounds and scopolin-related chemicals. Deficiencies of boron, calcium, magnesium, nitrogen, phosphorus, potassium, and sulfur have all been reported to enhance the concentration of chlorogenic acids and scopolin in a variety of plants (4). In other species, chlorogenic acids have decreased in plants that are deficient in magnesium or potassium. 

Operating staff at the plant consist of two operators per shift plus one maintenance person on dayshift. The wastewater is nutrient deficient and a ratio of 100 8 1 of BOD N P is maintained by the addition of diammonium phosphate and phosphoric acid for nitrogen and phosphorous requirements, respectively. 

Nutritional surveys indicate that children of low-income groups consume less than recommended dietary allowances of calcium and iron. Dietary deficiencies of these two minerals have been shown to potentiate the toxicity of lead (Johnson and Tenuta 1979 Yip et al. 1981 Ziegler et al. 1978). Thus, nutrient deficiencies in conjunction with a developmental predisposition to absorb lead makes this subset of children at a substantially elevated risk. More information on children s susceptibility to lead is presented in Section 2.6. 

As tree fruit species are perennial crops, year-to-year influences are often detected. For example, factors in the previous year(s) (e.g. water or nutrient deficiency, hail storm damage, shoot deformation caused by aphids, too high or too low crop load) strongly influence the tree s performance in the next year (Tromp and Wertheim, 2005). Thus, a major objective of agronomic practices used is to buffer the orchard from stress and to keep trees in a balance/equilibrium between vegetative and generative activity. 

Single-nutrient deficiencies can occur, usually in combination with any protein-energy malnutrition. 

Polycarbonyl and polyamino compounds include chelates, which are manmade compounds, and siderophores, which are biologically derived and more specialized. They can help dissolve inorganic ions, keep ions in one specific ionic state, and maintain them in biologically available forms. Because of their ability to bring ions into solution, they are often used to extract specific ions in specific forms from soil. Cationic micronutrients, particularly iron and zinc, are often applied in chelated form as a foliar spray to alleviate nutrient deficiencies. This is particularly true of plants growing in basic soil and is done even when plants do not show micronutrient deficiencies. Typically, both foliar and soil applications are effective in this regard. 

In the case of a nutrient there is a low-dose adverse effect due to nutritional inadequacy, but the nature of the adverse effect is completely different from that which becomes manifest as the region of high-dose toxicity is entered. Also, the very large risk associated with severe nutrient deficiency at doses near zero is not at all present in the case of hormesis. 

Release rates of exudates from phytoplankton range from 0 to 80% of carbon fixed. These rates are dependent on species composition, physiological state, nutrient deficiency, temperature, and Ught limitation. Some evidence suggests that exudation is a mechanism for release of excess organic matter from cells when nutrient availability is too low to enable their usage as metabolic fuel. 

This chapter is concerned with the different types of wetland soil as sources, sinks and transformers of nutrients, particular nutrient deficiencies and mineral toxicides that commonly arise following submergence, and the fate of pollutants that are commonly added to submerged soils, both accidentally and intentionally. 

Some pests, diseases, and disorders, and the techniques and materials listed here for prevention and control, are given fuller descriptions, and often pictured, in the chapter on Plant Health (pp.82-103) including mineral (nutrient) deficiencies, biological controls, traps and barriers, and "organic" fungicides and pesticides. Chapter 2, The Soil, contains more information on soil nutrient content and soil chemistry and pH pp.30-33). 

An adequate and balanced supply of nutrients in the soil is essential for several reasons. Nutrient surpluses might result in nutrient losses which subsequently could lead to water and air contamination (see chapter 3.2.2 and 3.2.3) and eutrophication. However, nutrient deficiency is synonymous with the overexploitation of soil nutrients in the long run and leads to a decrease in yield and product quality. 

---