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Rare earth elements (REEs) are widely distributed in low concentrations in all parts of the biosphere. REEs are not at all rare, their concentration in the earth’s crust is close to 0.015%. REEs include the elements scandium, yttrium and the lanthanides from lanthanum to lutetium. REEs show similar physical and chemical properties. Today REEs are applied in industries and technologies, in agriculture as microfertilizers and feed additives and they are also used in medicine. REEs are dispersed especially as accessory minerals in pegmatites, granites and associated metamorphic volcanic rocks. Out of more than 250 kinds of minerals containing REEs, only bastnaesite and monazite are of economic importance. Their concentration in the soil varies widely and depends on their presence in parental materials, soil texture, organic matter content, pedogenetic processes and anthropogenic activities. REEs are found in small concentrations in surface stagnant and flowing waters as well as in underground waters. They are found in water in both suspended and dissolved form. REEs enter the atmosphere from various sources, largely owing to human activities. The majority of REEs in the atmosphere are carried by microscopic particles. The uptake and consequently accumulation of REEs in plants are affected by numerous biotic factors, such as plant species and genotype, and abiotic factors such as their concentration in the soil and some chemical and physical soil characteristics. They can enter plants via both root and foliage tissues. There are plant species called hyperaccumulators that are able to accumulate significant amounts of REEs without adverse consequences. RREs are not biogenic for higher plants or for other living organisms, but can influence their life processes. Experi­ments show that REEs can be beneficial for growth, yield and biochemical composition of cultivated plants. They can also alleviate some ecological stress in plants. It is not clear enough how they affect human and animal health. The wide-spread application of REEs in different industries as well as in agriculture lead to a constant increase of the concentrations of these elements in the environment. Therefore, studies on the uptake, accumulation, dis­tribution of REEs in cultivated plant species and their entrance into the food chain as well as their stimulating or toxic effect on living organisms, can be very significant in the future.

Rare earth elements (REEs) are a group of chemical elements that include lanthanides as well as scandium and yttrium. Today REEs are used in various industries, such as agriculture where they are used as micro fertilizers and feed additives, the latter being used in medicine as well. There is no indication that REEs might be essential for any form of life. At lower concentrations, they can favorably influence certain physiological processes of plants (enzyme activity, hormone content, photosynthesis, seed germination, plant growth, etc.). They may induce an increase in some antioxidant systems and thereby increase the tolerance of plants to environmental stressors caused by high concentrations of heavy metals, herbicides, lack of water and essential nutrients, UV radiation and oxidative stress. Thus, their favorable effect was documented regarding the yield of cultivated species as well as the effect of their chemical composition on the content of vitamin C, soluble sugars and essential elements, reduction of the concentration of toxic heavy metals, improvement of the quality of wheat kernel for different uses. REEs have been commonly used as feed additives in organic and inorganic forms in livestock production. The available literature on the use of REEs as feed additives in livestock suggests positive outcomes (affected various physiological processes, increase in milk, egg and meat production, promoted growth and reproductive performance), but further investigation and results are needed before extending their use to zootechnical purposes.

Nickel (Ni) is an essential microelement for higher plants and an important one for many other living organisms. It is present in every part of the biosphere. Higher plants have small requirements towards Ni for their optimal growth and development. That is why its latent and acute deficiencies in nature rarely occur. Soil and water pollution with Ni is a global issue. This is the reason special attention is paid to the effects of higher Ni concentrations on plants metabolism, their organic production, as well as on the possibility of using plants for phytoremediation of Ni contaminated habitats. Depending on the present concentrations, nickel may favourably, unfavourably or not affect the metabolic processes of plants at all (enzyme activity, photosynthesis, respiration, water regime, mineral nutrition, etc.), and thus the growth and development of plants. There are still many questions about the mechanism of Ni influence on the physiological and biochemical processes of plants. Therefore, we believe the presentation of the previous knowledge about the effect of Ni on plants' life processes can contribute to a better understanding of the biotechnical and ecological significance of Ni, and it can indicate further research directions in this field.

Iodine (I) is widely distributed in the biosphere in small concentrations. Iodide (I-) and iodate (IO3-) are the most important inorganic forms of I that can be found in the biosphere. Iodine is a necessary microelement for some marine algae and higher animals. Approximately 35% of the world’s population is insufficiently provided with I, which results in many health problems. Plants are an important source of I for humans, and the knowledge about the uptake, distribution, and accumulation of I in edible plant parts, as well as its effect on life processes and organic production of cultivated species is very important. The results of numerous studies indicate a favorable effect of I application on plant growth, tolerance to stress, and the antioxidant capacity of plants. In addition, its effects on photosynthesis, hydration, carbohydrate metabolism, respiration, and interaction with other elements are analyzed. At the same time, data are indicating that the application of I has no effect, moreover, it may act phytotoxically, especially at higher concentrations. Based on the current understanding of I impact on life processes and the organic production of higher plants, it can be considered a useful element. Plants can complete their life cycle without iodine, but it may have a stimulating effect on their growth under certain circumstances. Considering the importance of I for the health of the human population and higher animals, the application of I to increase its concentration in edible parts of grown plants using cultivation practices (biofortification of crops with I) is an important task for further research.

In this study, the effect of Cd on the germination, growth of seedlings and composition of plants deriving from contaminated grains, grown in the field, was ex­amined. Wheat grains were soaked in Cd-containing solutions: 0 (control, deionized water), 10-5, 10-4, 10-3, and 10-2 M CdCl2 during 24h. One portion of grains was used to test germi­nation and seedling growth, while the other was sown in the field. The concentration of Cd in the grains almost linearly increased with the increase in the applied concentrations of Cd, which reduced the germination and energy of germination and increased the proportion of atypical seedlings. Larger concentrations of Cd significantly impaired the growth of seedlings (length of the shoots and roots, dry matter mass). In the grains of the field-grown plants the concentrations of N, P, and K were not affected by Cd, but their concentrations in the straw declined (especially of N). These results suggest that the emergence and development of plants on the soil polluted by Cd are likely to be significantly limited and yield reduced. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR 31016]

Even though calcium (Ca), strontium (Sr) and barium (Ba) belong to the same group of the periodic table of elements, and thus have similar chemical features, their importance for plants differs greatly. Since plants do not have the ability to completely dis­criminate between essential (e.g. Ca) and non-essential elements (e.g. Sr and Ba), they read­ily take all of them up from soil solution, which is reflected in the ratios of concentrations of those elements in plant tissues, and it influences their nutritive characteristics. The ability of plant species and genotypes to take up and accumulate chemical elements in their different tissues is related to their genetic background. However, differences in chemical composition are the least reflected in their reproductive parts. Hence, the aim of this study was to evaluate ratios of concentrations of Ca, Sr and Ba in the whole grain of diploid and tetraploid wheat - ancestors of common wheat, as well as in hexaploid commercial cultivars, grown in the field, at the same location, over a period of three years. The investigated genotypes accumulated Ca, Sr and Ba at different levels, which is reflected in the ratio of their concentrations in the grain. The lowest ratio was established between Ba and Sr, followed by Ca and Ba, while the highest ratio was between Ca and Sr. Moreover, the results have shown that the year of study, genotype and the combination highly significantly affected the ratio of the concentration Ca:Sr, Ca:Ba, and Ba:Sr.

(Carthamus tinctorius L.) is highly regarded in the world as an aromatic, spicy, medicinal and oilseed crop, which can be used in all kinds of industries. It inhabits arid and semiarid areas of the world. The influence of the relatively low NaCl concentrations found in soils and irrigation waters on the growth and metabolism of saf­flower, grown under semi-controlled conditions, was examined in this work. It was found that increased concentrations of NaCl affected the number of leaves per plant and dry leaves mass/area ratio. The transpiration intensity was reduced in plants grown in the presence of NaCl and stomatal diffusive resistance increased following an increase in NaCl concentration.

The aim of this study was to evaluate the concentration of barium in grain of various Aegilops and Triticum species with different genomes. The studied species differed significantly with respect to the concentration of barium. The grain of wild diploid Aegilops speltoides, the donor of B genome, contained significantly higher Ba concentration than all other analyzed genotypes. Wild and cultivated tetraploid wheats (Triticum diciccoides, Triticum dicoccon, Triticum turgidum and Triticum durum) had the lowest Ba concentration in grain. The modern cultivated hexaploid varieties presented substantial variation in grain concentration of barium. The highest Ba concentration (3.42 mg/kg) occurred in Serbian winter wheat variety Panonnia.

Some plants from the genus Brassica have the ability to tolerate excessive concentrations of heavy metals, including Ni. Considering the fact that Ni is a very toxic element for living beings we wanted to examine its influence on some species from genus Brassicaceae. The aim of this study was to investigate the effect of Ni on distribution and accumulation of essential macronutrients from the standpoint of food quality and phytoremediation potential. Experiments were performed using winter (W) and spring (S) varieties of rapeseed (Brassica napus, L.), white mustard (Brassica alba, L.), black mustard (Brassica nigra, L.) and turnip (Brassica rapa, L.). The seeds were exposed to 10 μM Ni from the beginning of germination. Plants were grown in water cultures, in semi-controlled conditions of a greenhouse, on ½ strength Hoagland solution to which was added Ni in the same concentration as during germination. Concentrations and distribution of Ca, Mg, K in leaf and stem were altered in the presence of increased concentration of Ni. Significant differences were found between the control and Ni-treated plants as well as among the genotypes. [Projekat Ministarstva nauke Republike Srbije, br. TR 31036 i br. TR 31016]

Effect of treatment of seed with various lead concentrations (0, 10-5, 10-4, 10-3, and 10-2 mol/dm3) on accumulation and distribution of lead (Pb) in seedling, seed germination, seedling growth, and mobilization of mineral matter during seed germination was investigated. Content of Pb in the root and the shoot indicates that seeds imbibed in solutions of various Pb concentrations took up Pb intensively. Content of Pb in the root and the shoot increased with increase of Pb concentration and it was much larger in the root than in the shoot. Contrary to this, the accumulation coefficient was greater in the shoot than in the root. Treatment of seed with Pb did not significantly affect its biological properties. Increase of Pb concentration decreased germination ability, germination energy, and percentage of typical seedlings, while increasing the number of atypical seedlings and non-germinated seeds. Contamination of seed by Pb did not affect the dry matter mass and the growth of young plants shoots, while the length of the primary root, the mesocotyl root as well as the root mass at the highest Pb concentration, significantly decreased. Translocation of mobilized mineral matter from the seed during germination and growth of young plants into the root and shoot was specific, depending on elements. Only the implementation of the highest implemented Pb concentration affected mobilization and translocation of some elements. Based on the obtained results, it can be concluded that maize is characterized by significant tolerance to Pb contamination during seed germination and growth of seedlings.

Effect of different concentrations of nickel (0, 10-5, 10-4, 10-3 and 10-2 mol Ni/dm3) present at the time of maize seed imbibition, on concentration, distribution and nickel accumulation coefficient in the root and the shoot, biological value of the seed and growth of young plants was investigated. It was found that during germination the nickel from the seed is intensively translocated to the root and shoot of young plants. With increase of applied concentrations of nickel, its concentration in the root and shoot increased as well. Nickel concentration and accumulation coefficient were higher in the root than in the shoot except at the highest applied concentration when the result was opposite. The highest applied concentration of nickel increased percentage of atypical seedlings and non-germinated seeds and decreased percentage of typical seedlings, germination energy and seed germination ability. Nickel implementation did not affect the growth and mass of the shoot. Root mass and length of the primary root decreased at the highest concentration of nickel, which led to change in shoot and root mass ratio. Based on the obtained results it can be concluded that only the highest applied nickel concentration affected the biological value of the seed and the growth of young maize plants, regardless of its intensive accumulation in the root and the shoot, which indicates a significant tolerance of maize in initial phases of growth to presence of high nickel concentration. Intensive translocation of nickel during germination into newly formed organs points to its good mobility and potential possibility to enter the food chain from a contaminated seed.

Eleven sugar beet genotypes were tested for their capacity to tolerate drought. Plants were grown in semi-controlled conditions, in the greenhouse, and watered daily. After 90 days, water deficit was imposed by the cessation of watering, while the control plants continued to be watered up to 80% of FWC. Five days later concentration of free proline in leaves was determined. Analysis was done in three replications. Statistical analysis was performed using STATISTICA 9.0, Minitab 15, and R2.11.1. Differences between genotypes were statistically processed by Duncan test. Because of nonormality of the data distribution and heterogeneity of variances in different groups, two types of transformations of row data were applied. For this type of data more appropriate in eliminating nonormality was Johnson transformation, as opposed to Box-Cox. Based on the both transformations it may be concluded that in all genotypes except for 10, concentration of free proline differs significantly between treatment (drought) and the control.

Acid soils limit crop production on 30-40% of the world's arable land and up to 70% of the world's potentially arable land. Over 60% of the total arable lands in Serbia are acid soils. Soil acidity is determined by hydrogen (H+) in soil solution and it is influenced by edaphic, climatic, and biological factors. Major constraints for plant growth on acid mineral soils are toxic concentrations of mineral elements like Al of H+ and/or low mineral nutrient availability due to low solubility (e.g. P and Mo) or low reserves and impaired uptake (e.g. Mg2+) at high H+ concentrations. Aluminum (Al) toxicity is primary factor limiting crop production on acid soils. This review examines our current understanding of mechanisms of Al-toxicity, as well as the physiological and genetic basis for Al-toxicity and tolerance. Inhibition of root growth by Al leads to more shallow root systems, which may affect the capacity for mineral nutrient acquisition and increase the risk of drought stress. Of the two principal strategies (tolerance and avoidance) of plants for adaptation to adverse soil conditions, the strategy of avoidance is more common for adaptation to acid mineral soils. At the same, the short view of the most important genetics tolerance mechanisms, developed and determined in some small grains genotypes, is showed as well.

The aim of this work was to investigate genetic specificity of sunflower nutrition with microelements. Therefore, concentrations of essential (Zn, B, Mn, Cu, Fe and Ni) and non-essential (Cr, Al, Cd, As, Pb and Ba) micronutrients were analyzed. Five sunflower hybrids the most grown in Serbia and different populations of wild sunflower species originating from North America: Helianthus neglectus Heiser (3), Helianthus agrophyllus T&G (3), Helianthus petiolaris Nutt. (2), Helianthus annuus L. (4) were included in the experiment. Populations of wild sunflower species and hybrids differed significantly with respect to the concentration of analyzed elements. Manganese concentration was significantly higher in hybrids than in wild species. In all genotypes Fe, B and Mn had the highest concentration. Coefficient of variation of microelement concentration depended on genotype and particular element. In wild populations, for essential microelements, it was between 3.7 and 59.5, whereas in hybrids it varied from 10.0 to 48.8. Coefficient of variation of concentration of non-essential microelements in wild populations varied from 7.7 to 73.8, and in hybrids from 15.1 to 48.8. Average coefficient of variation in both wild species and hybrids was the lowest for Mn and Pb. It was the highest for Cr, Ni, and Zn in hybrids and for Cd, Ni, and Cr in wild species. The results suggest that genetic specificity with respect to uptake of microelements in wild species and hybrids is highly expressed. Broad genetic variability of concentrations of microelements in wild species and hybrids indicate that their reactions to deficiency and/or excess of those elements probably are not the same either. This finding may be used in breeding process aimed specifically at improvement of tolerance and capacity to accumulate microelements in sunflower. Phytoremediation technology designed to reduce the amount of microelements in the soil could thus be advanced by utilization of such plants.

Rare earth elements (REEs) form a chemically uniform group with very similar physical and chemical properties. The REEs include the elements scandium, yttrium, and the lanthanides from lanthanum to lutetium. They are widely distributed and present in all parts of the biosphere. REEs are required in industry, agriculture, medicine, biotechnology, environmental problems and many other fields. Lately, many experiments show their positive or negative, first of all nonspecific, effect on life processes of higher plants as well as growth and yield of cultivated species, but the physiological mechanisms are still not well understood. It has been determined that yttrium is widely distributed in plants, as well as that certain plant species uptake yttrium at different extent. Its highest accumulation is in the root and the leaf. Although yttrium was discovered more than two centuries ago, its effect on higher plants - their anatomical and morphological built, physiological and biochemical processes etc. - is very little known. One of the basic reasons is that yttrium, as well as other REEs elements, according to current knowledge, is not biogenic for higher plants and - wider - for live organisms. The objective of this paper is to concisely show previous knowledge about yttrium in the plant world.

Reactive oxygen species (ROS), such as O2·¯, are formed by electron transfer to a molecule with stable electron configuration, in electron transport chains in the cell. ROS are very reactive molecules which are formed at higher rates under stress, such as drought, high insolation, heath, inadequate mineral nutrition, and such conditions lead to impairment of various physiological and biochemical processes in the cell. To reduce production of ROS, and their detrimental effect, plants developed various enzymatic and non-enzymatic protective mechanisms. Superoxide dismutase (SOD) is one of the most important antioxydative enzymes, which removes superoxid anion radical (O2·¯), whose rate of production is the highest under unfavorable environmental conditions. Plant tissues that exhibit delayed senescence often have higher cytokinin content, which is accompanied by reduced amount of ROS. The focus of this paper is to examine whether foliar application of cytokinins to young wheat plants insufficiently supplied with nitrogen affects the activity of SOD and amount of O2·¯. Application of trans-zeatine (CK) reduced the activity of SOD, but this reduction was not accompanied by an increase in the amount of O2·¯. Application of benzyl adenine (BA) also reduced the activity of SOD, with concomitant increase in the amount of O2·¯ in wheat leaves.

Magnesium content was analyzed in five of the most grown sunflower hybrids in Serbia, as well as in different populations of wild sunflower species: Helianthus agrophyllus (5), Helianthus annuus (4), Helianthus neglectus (3), Helianthus petiolaris (5), Helianthus tuberosus (5). Magnesium content in the populations of wild sunflower species ranged from 317 to 824 mg/100 g DW. The highest magnesium content was found in Helianthus petiolaris and the lowest in Helianthus tuberosus. Different populations within each species differed significantly in magnesium content. The highest variation coefficient was found in Helianthus tuberosus and the lowest in Helianthus petiolaris. Magnesium concentration in hybrids was significantly different as well, and in two years it was in average between 575 and 813 mg/g DW. The results suggest that genetic variability between magnesium concentrations in wild species and hybrids of sunflower is very high. This should be taken into consideration when requirements for mineral nutrition are analyzed, as well as when wild species are included in breeding programs.

Boron (B) deficit as well as excess may significantly limit the organic production in plants. In extreme cases they may kill the affected plants. Boron excess occurs primarily in arid and semiarid regions, in saline soils or in consequence to human action. Excessive boron concentrations retard plant growth and cause physiological and morphological changes (chlorosis and necrosis) first of all in leaf tips and then in marginal or intercostal parts of the lamina. Physiological mechanisms of plant tolerance to boron excess have not been studied in sufficient detail. The predominant opinion holds that they are based on restricted uptake and accumulation of boron in the root and aboveground plant parts. Significant differences in boron excess tolerance have been observed not only between different crops but even between different genotypes of the same crop. This has enabled the breeding of crop genotypes and crops adapted to growing on soils rich in available boron and intensified the research on the inheritance of plant tolerance to high B concentration. Sources of tolerance to high B concentration have been found in many crops (wheat, mustard, pea, lentil, eucalypt). Using different molecular techniques based on PCR (RAPD, SRAP), plant parents and progenies have been analyzed in an attempt to map as precisely as possible the position of B-tolerant genes. Small grains have been studied in greatest detail for inheritance of B tolerance. B tolerance in wheat is controlled by at least four additive genes, Bo1, Bo2, Bo3 and Bo4. Consequently, there exists a broad range of tolerance levels. Studies of Arabidopsis have broadened our understanding of regulation mechanisms of B transport from roots to above ground parts, allowing more direct genetic manipulations.

An investigation has been conducted on the effect of reduced water potential in nutrient solution on the accumulation of some essential macro- and micro nutrients in the aboveground pails of young sugarbeet plants. Plants of 8 different sugarbeet genotypes were exposed for 21 days to a nutrient solution whose water potential of 0.1 MPa was regulated by PEG. Contents of N, P, K Ca, Mg, Fe, Mn, Cu and Zn declined in all genotypes under water deficiency but the intensity of reduction varied among the genotypes. The results indicated that some harmful effects of water deficiency could be attributed to disturbances in plant mineral nutrition, especially the lack of N, P, and Mg, as well as to impaired ratios between the contents of particular elements, especially K/Ca.

In the base, working of ventilation system can be analyzed in regular and incidental modes of operation. This paper concerns the specification of the longitudinal ventilation necessary to prevent upstream movement of combustion products in a tunnel fire. In this work the objective of the study is to analyze the road way tunnel ventilation system using CFD software to create comfort ventilation system in the tunnel. The comfort ventilation concept refers to the situation when air quality within the tunnel is reduced due to presence of polluted air in the tunnel. This paper is focused on ventilation system in a road traffic tunnel in moment of accident situation as fire. In this investigation numerical simulation of fire was carried out and determination of a critical air velocity depending on the power of the fire was conducted. The output results of the software developed for this purpose, which is also used in the realization of practical projects, are shown. [ABSTRACT FROM AUTHOR]

Eleven sugar beet genotypes were tested for their capacity to tolerate drought. Plants were grown in semi-controlled conditions, in the greenhouse, and watered daily. After 90 days, water deficit was imposed by the cessation of watering, while the control plants continued to be watered up to 80% of FWC. Five days later concentration of free proline in leaves was determined. Analysis was done in three replications. Statistical analysis was performed using STATISTICA 9.0, Minitab 15, and R2.11.1. Differences between genotypes were statistically processed by Duncan test. Because of nonormality of the data distribution and heterogeneity of variances in different groups, two types of transformations of row data were applied. For this type of data more appropriate in eliminating nonormality was Johnson transformation, as opposed to Box-Cox. Based on the both transformations it may be concluded that in all genotypes except for 10, concentration of free proline differs significantly between treatment (drought) and the control. [ABSTRACT FROM AUTHOR]

Effect of different concentrations of nickel (0, 10-5, 10-4, 10-3 and 10-2 mol Ni/dm³) present at the time of maize seed imbibition, on concentration, distribution and nickel accumulation coefficient in the root and the shoot, biological value of the seed and growth of young plants was investigated. It was found that during germination the nickel from the seed is intensively translocated to the root and shoot of young plants. With increase of applied concentrations of nickel, its concentration in the root and shoot increased as well. Nickel concentration and accumulation coefficient were higher in the root than in the shoot except at the highest applied concentration when the result was opposite. The highest applied concentration of nickel increased percentage of atypical seedlings and non-germinated seeds and decreased percentage of typical seedlings, germination energy and seed germination ability. Nickel implementation did not affect the growth and mass of the shoot. Root mass and length of the primary root decreased at the highest concentration of nickel, which led to change in shoot and root mass ratio. Based on the obtained results it can be concluded that only the highest applied nickel concentration affected the biological value of the seed and the growth of young maize plants, regardless of its intensive accumulation in the root and the shoot, which indicates a significant tolerance of maize in initial phases of growth to presence of high nickel concentration. Intensive translocation of nickel during germination into newly formed organs points to its good mobility and potential possibility to enter the food chain from a contaminated seed. [ABSTRACT FROM AUTHOR]

Acid soils limit crop production on 30-40% of the world's arable land and up to 70% of the world's potentially arable land. Over 60% of the total arable lands in Serbia are acid soils. Soil acidity is determined by hydrogen (H+) in soil solution and it is influenced by edaphic, climatic, and biological factors. Major constraints for plant growth on acid mineral soils are toxic concentrations of mineral elements like Al of H+ and/or low mineral nutrient availability due to low solubility (e.g. P and Mo) or low reserves and impaired uptake (e.g. Mg2+) at high H+ concentrations. Aluminum (Al) toxicity is primary factor limiting crop production on acid soils. This review examines our current understanding of mechanisms of Al-toxicity, as well as the physiological and genetic basis for Al-toxicity and tolerance. Inhibition of root growth by Al leads to more shallow root systems, which may affect the capacity for mineral nutrient acquisition and increase the risk of drought stress. Of the two principal strategies (tolerance and avoidance) of plants for adaptation to adverse soil conditions, the strategy of avoidance is more common for adaptation to acid mineral soils. At the same, the short view of the most important genetics tolerance mechanisms, developed and determined in some small grains genotypes, is showed as well. [ABSTRACT FROM AUTHOR]

Rare earth elements (REEs) form a chemically uniform group with very similar physical and chemical properties. The REEs include the elements scandium, yttrium, and the lanthanides from lanthanum to lutetium. They are widely distributed and present in all parts of the biosphere. REEs are required in industry, agriculture, medicine, biotechnology, environmental problems and many other fields. Lately, many experiments show their positive or negative, first of all nonspecific, effect on life processes of higher plants as well as growth and yield of cultivated species, but the physiological mechanisms are still not well understood. It has been determined that yttrium is widely distributed in plants, as well as that certain plant species uptake yttrium at different extent. Its highest accumulation is in the root and the leaf. Although yttrium was discovered more than two centuries ago, its effect on higher plants -- their anatomical and morphological built, physiological and biochemical processes etc. -- is very little known. One of the basic reasons is that yttrium, as well as other REEs elements, according to current knowledge, is not biogenic for higher plants and -- wider -- for live organisms. The objective of this paper is to concisely show previous knowledge about yttrium in the plant world [ABSTRACT FROM AUTHOR]

The aim of this work was to investigate genetic specificity of sunflower nutrition with microelements. Therefore, concentrations of essential (Zn, B, Mn, Cu, Fe and Ni) and non-essential (Cr, Al, Cd, As, Pb and Ba) micronutrients were analyzed. Five sunflower hybrids the most grown in Serbia and different populations of wild sunflower species originating from North America: Helianthus neglectus Heiser (3), Helianthus agrophyllus T&G (3), Helianthus petiolaris Nutt. (2), Helianthus annuus L. (4) were included in the experiment. Populations of wild sunflower species and hybrids differed significantly with respect to the concentration of analyzed elements. Manganese concentration was significantly higher in hybrids than in wild species. In all genotypes Fe, B and Mn had the highest concentration. Coefficient of variation of microelement concentration depended on genotype and particular element. In wild populations, for essential microelements, it was between 3.7 and 59.5, whereas in hybrids it varied from 10.0 to 48.8. Coefficient of variation of concentration of non-essential microelements in wild populations varied from 7.7 to 73.8, and in hybrids from 15.1 to 48.8. Average coefficient of variation in both wild species and hybrids was the lowest for Mn and Pb. It was the highest for Cr, Ni, and Zn in hybrids and for Cd, Ni, and Cr in wild species. The results suggest that genetic specificity with respect to uptake of microelements in wild species and hybrids is highly expressed. Broad genetic variability of concentrations of microelements in wild species and hybrids indicate that their reactions to deficiency and/or excess of those elements probably are not the same either. This finding may be used in breeding process aimed specifically at improvement of tolerance and capacity to accumulate microelements in sunflower. Phytoremediation technology designed to reduce the amount of microelements in the soil could thus be advanced by utilization of such plants. [ABSTRACT FROM AUTHOR]