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Typical symptoms of heavy metals toxicity are often similar or even the same like symptoms of some essential nutrients deficiency. The aim of this paper is to discuss mechanisms of some heavy metals uptake and possible ways of their influence on some basic and trace nutrients availability for plants. Attention is also paid to regulatory relationships among groups of heavy metals themselves. Moreover, possibilities and limitations in revitalization of heavy metal-treated plants by micro-, and macronutrient supply are discussed

Chromium has been studied since the end of the 19th century, when carcinogenic effects of hexavalent Cr were discovered. Essentiality of trivalent Cr was demonstrated in 1959; Cr3+ has been studied in humans and laboratory animals since the 1970s and it is only since the 1990s that Cr has been studied as an essential element in livestock animals with the same intensity. Trivalent Cr is essential to normal carbohydrate, lipid and protein metabolism. It is biologically active as part of an oligopeptide - chromodulin - potentiating the effect of insulin by facilitating insulin binding to receptors at the cell surface. Cr absorption is low, ranging between 0.4 and 2.0% for inorganic compounds while the availability of organic Cr is more than 10 times higher. Absorbed Cr circulates in blood bound to the beta-globulin plasma fraction and is transported to tissues bound to transferrin. Absorbed Cr is excreted primarily in urine, by glomerular filtration; a small amount is excreted through perspiration, bile and in milk. This review describes Cr metabolism, the different biological functions of Cr and symptoms of Cr deficiency.

▪ Abstract  New and exciting developments in boron research in the past few years greatly contributed to better understanding of the role of boron in plants. Purification and identification of the first boron-polyol transport molecules resolved much of the controversy about boron phloem mobility. Isolation and characterization of the boron-polysaccharide complex from cell walls provided the first direct evidence for boron crosslinking of pectin polymers. Inhibition and recovery of proton release upon boron withdrawal and restitution in plant culture medium demonstrated boron involvement in membrane processes. Rapid boron-induced changes in membrane function could be attributed to boron-complexing membrane constituents. Boron may affect metabolic pathways by binding apoplastic proteins to cis-hydroxyl groups of cell walls and membranes, and by interfering with manganese-dependent enzymatic reactions. In addition, boron has been implicated in counteracting toxic effects of aluminum on root growth of dicotyledonous plants. Molecular investigations of boron nutrition have been initiated by the discovery of a novel mutant of Arabidopsis thaliana with an altered requirement for boron.

Cadmium, lead, mercury, and aluminum are toxic metals that may interact metabolically with nutritionally essential metals. Iron deficiency increases absorption of cadmium, lead, and aluminum. Lead interacts with calcium in the nervous system to impair cognitive development. Cadmium and aluminum interact with calcium in the skeletal system to produce osteodystrophies. Lead replaces zinc on heme enzymes and cadmium replaces zinc on metallothionein. Selenium protects from mercury and methylmercury toxicity. Aluminum interacts with calcium in bone and kidneys, resulting in aluminum osteodystrophy. Calcium deficiency along with low dietary magnesium may contribute to aluminum-induced degenerative nervous disease

Despite its abundance in the earth's crust, iron deficiency is a serious health issue in many parts of the world. Although fundamental observations about iron metabolism and the significance of iron nutriture were first noted some time ago, the molecular mechanisms involved in iron metabolism are just now being defined

Sugar beet ranks among very intensive field crops. To ensure yield stability it is necessary to choose soil of high quality fertilised with farmyard manure after harvesting the preceding crop. This will improve the physical and chemical properties of the soil and under favourable weather conditions will ensure a balanced emergence rate of the plants. An optimal content of P, K and Mg in the soil at a level of good supply has a favourable effect on plant growth and development and positively affects the technological quality of the tubers. Under conditions of the Czech Republic, attention must be paid to sulphur and sodium fertilisation. A lower level of K fertilisers reduces the Na content in the soil and has to be solved by using fertilisers with a low percent of K which also provide the shortage sodium. When the content of the basic fertilisers is balanced, the decisive factor in terms of the yields and tuber quality is nitrogen. The N rate is determined on the basis of Nmin in the soil in the 0-0.6 m laye. Nitrogen is incorporated into the soil 1-2 weeks prior to sowing, in this way reducing the danger of unbalanced rate of emergence of the sugar beet. With low rates of N additional fertilisation of sugar beet is provided after emergence of the plants. Additional N fertilisation is carried out only exceptionally with nitric forms of N fertilisers before the end of May.

Twenty-eight dairy cows were divided into experimental (E) and control groups (C) and monitored within the first 100 days of lactation. The diet of both groups differed in lipid concentration (3.7% of dry matter in C vs 6.99% in E ). At the end of the first month, a higher degree of energetic metabolism disturbance as well as a higher occurrence of liver damage were determined in group E in comparison with group C. Concentrations of cholesterol, HDL-cholesterol and vitamin E increased during the experiment so that in the 3rd month, their values were almost double in E than in C cows. The proportion of HDL-cholesterol was lower and the total antioxidant status of blood serum was higher in E than in C animals. Milk protein concentration was significantly lower (3.18 vs. 3.45%) and milk fat concentration insignificantly higher (3.55 vs. 3.21%) in E than in C cows. Feeding of high doses of lipid during the first month after parturition led to the risk of a fatty liver, but no negative impact on the health was demonstrated during the peak period of lactation.