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Urban vegetation affects the environment in several ways. It improves air quality, the height of drainage water, and soil properties, balances temperature variations (temperatures are lower in summer and higher in winter in the presence of urban vegetation), reduces UV radiation, reduces noise, increases relative air humidity and contributes to certain types of social development (ecological, aesthetic, economic aspects of urban development). Urban vegetation especially improves microclimatic conditions in large cities and considerably contributes to the urban increase of oxygen. It is of vital interest to pay attention to its size and quantity in urban areas. To assess CO2 absorption and O2 release, the photosynthesis of five tree species and three types of herbaceous plants species was measured. The obtained results show that there is a certain variability in terms of the species that was analyzed. Thus, fast-growing woody deciduous species are more suitable due to the greater and faster growth of biomass, which requires a larger amount of CO2 compared to herbaceous species. The careful calculation indicates the requirement of two to four trees per person or 30-40 m2 of a grassy area per person to balance the inhabitant oxygen consumption. For the overall contribution of green vegetation, the multiple qualitative benefits of green areas in urban areas should certainly be considered.

The utilization of ash obtained as a result of the combustion of fossil fuels (coal, peat) or biomass (straw, wood, solid waste) is an environmental problem that should be optimally solved. The chemical characteristics of ash depend on several factors, mostly on sources of fuel. According to characteristics, ash can be used in agriculture, forestry, or utilized for other purposes. The content of heavy metals (Cd, Ni, Pb, Cr) in peat ash is several times higher than in willow wood ash and straw ash. It means that peat ash application is limited to agricultural crops and its optimal application is one year before planting SRC trees, especially on poor and acid soils. The application of peat ash at a dose of 10 mg dry mass ha-1 in willow plantations on post-mining peaty soils changed soil acidity from 5.2 pH to 5.88 pH and stimulated tree growth. Wood and straw ash was applied to wil­low plantations on arable loam-sandy soils in doses 0.5, 1.0, and 1.5 t dry mass ha-1. The positive effect of ash application in doses 1.0 and 1.5 t dry mass ha-1 showed in the second year after the application both for soil and for willow growth.

The goal of this research is an assessment of the possible use of peatlands biomass and straw for the production of mixed bio-pellets. Peaty soils are a specific type of soils formed as the result of wetlands drainage. Peat mining is completed by the factory if the layer of the peat is less than 1-2 meters and not enough deep for effective mechanical excavation. After the peat excavation is finished, the biggest problem is the use of these lands for other purposes. One of the perspective directions is rewetting of post-mining peatlands to stimulate the growth of common reed, cattail, fescue, sedge, and other grasses which may grow in natural conditions, and also improve conditions for the cultivation of other plants, including trees. The yield of wetland grass in Belarus varies from 8.1 to 14 DM g ha-1 per year. The yield of willow wood can reach 8-10 of DM g ha-1 per year. The highest prime cost of biomass is obtained for willow wood, but it will be lower with the enlargement of the plantation area. Pellets with a high content of wood residues (sawdust) have the best technological parameters including calorific value when compared to pellets from only peat and peat plus straw. Biomass production on degraded peaty soils has also an ecological effect. The cost of carbon quotas on the market varies from 20 to 25 euro per ton, and biomass production can provide additional profit in the case of CO2 emissions trading depending on the biomass content in the fuel.

Alternative or renewable energy is a modern strategy with a good per­spective in the nearest future. There are several directions of renewable energy development that depend on climatic, economic and technological opportunities of a region. The perspective choice for areas with moderate climate is bioenergy. One of the bioenergy directions is agro forestry based on short rotation coppice plantations (SRC) of trees, like willow, poplar and others. The goal of experiments was the assessment of the potential of different willow species for the obtaining of energy in two climatic zones and on two types of soils of Belarus. For this purpose several morphological characteristics were metered: height of plants, biomass, diameter and number of sprouts. The field experiments were conducted on two types of soils: post-mining peaty soils in Grodno region and on degraded peaty soils in Brest region of Belarus. The same soils are very problematic for growing of traditional agricultural crops, thus willow production is a good alternative for biomass production of energy as well as for the reclamation of these soils. In our experiments the following species of willow were tested (Salix alba, Salix viminalis, Salix dasyclados, Salix aurita) that may grow on peaty soils at the natural conditions. The most popular species for modern selection of SRC of willow is Salix viminalis. Nevertheless, the most suitable morphological characteristics on post-mining peaty soils were established for plants of Salix dasyclados and on degraded peaty soils for the plants of Salix alba. The unfavorable parameters at the both type of soils were identified for the plants of Salix aurita. However, it is necessary to take into account that the used species are more popular for natural wetlands and in our experiments plants have best results of survival of cutting and rates of growth at the beginning of vegetation. In accordance with these facts Salix aurita may not be used for energy plantation directly, but it is interesting for hybridization with other species. Our results have shown that perspective hybrids for peaty soils may be for instance Salix aurita x Salix dasyclados and Salix aurita x Salix alba.

Bioenergy production based on short rotation coppice willow plantations (SRC) is an effective direction both for economic and environment profit. The yield of willow wood can amount to 10-15 tons per hectare of dry biomass per year and the cost of thus obtained energy is lower in comparison with other energy crops. In order to achieve high yield and profitability, the use of special willow clones is necessary. Species most often used in selection for biomass production are shrub type willows: Salix viminalis, Salix dasyclados and Salix schwerini, while the clones tested in this paper were also of tree species Salix alba. The productivity and some physiology characteristics of Serbian selection clones of Salix alba (Bačka, Volmianka and Drina) and Swedish selection clone Jorr (Salix viminalis) were investigated in greenhouses and in field conditions. As the result of testing three clones of Salix alba - Bačka, Volmianka and Drina, having special preferences and adaptability to different environmental conditions, these were included in State register of Republic of Belarus in 2013. In our experiment it was also satisfactory that specific properties of willows (intensity of transpiration and photosynthesis, water use efficiency and others), were conserved both in greenhouses and in field conditions. This factor gives opportunity to select prospective clones of willows at an early stage of ontogenesis for further testing.

Heavy metals are the substances that indicate environmental pollution. The plants polluted with heavy metals may endanger natural environment and cause health problems in humans. In our multidisciplinary research of the concentrations of pollutants in forest ecosystems and natural environment in Belgrade, we examined the contents of heavy metals essential for plants but harmful in greater concentrations on a long-term basis. The fact that heavy metals manganese and iron are accumulated in plants to the greatest extent focused our work on determination of the level of concentrations of Mn and Fe in the vegetative parts of 8 plant types on three locations on the Avala Mountain and one location in the centre of the city of Belgrade. The analyses of heavy metals contents in plants were performed by the method of flame atomic absorption spectrophotometry. The examination of the existence of important differences between the average values was performed by implementation of Duncan’s test for the level of significance of 95%. The current contents of heavy metals in plants in the area of the protected natural resource Avala do not represent danger that would presently cause notable damage to forests but show the tendency of the increase of concentrations. Therefore, this issue should be constantly monitored.

The aim of this study was to examine variability of acorn anatomical characteristics in seventeen Quercus robur L. genotypes. Acorns were collected in clonal seed orchard Banov Brod (Srem, Vojvodina, Serbia). Microscopic measurements were done for pericarp (total thickness, thickness of exocarp and mesocarp), seed coat (total thickness, thickness of outer epidermis, parenchyma, and inner epidermis), and embryo axis (diameter, thickness of cortical region, and diameter of stellar zone). Obtained results revealed certain divergence between genotypes. The thickness of pericarp varied from 418 to 559 mm (genotypes 20 and 22, respectively). On average, the participation of exocarp in the total thickness of pericarp was 36.3%, of mesocarp 61.0%, while of endocarp 2.6%. The thickness of seed coat for individual genotypes ranged from 71 mm (genotype 28) to 157 mm (genotype 38). In addition, anatomic parameters of embryo axis varied among studied genotypes. The lowest cortical zone thickness and stellar zone diameter were measured in genotype 40, while the highest values in genotype 33.

Pepper (Capsicum annuum L.) is one of the major members of the vegetable kingdom. The differences between the individual varieties in mineral nutrition and the uptake of mineral elements have provoked our interest for the investigations of their genotype specificity. The chemical composition of pepper leaves at flowering and at the end of the growing season was analyzed. On the average, the content of total ash was app. 22%, namely 19-20% (soluble) and 2-3% (insoluble) at both stages. The highest accumulation values were obtained with nitrogen, then potassium, calcium and phosphorus, whereas the lowest with sodium. The most remarkable genotypic differences were recorded at the end of the growing season. The results obtained clearly demonstrate the chemical heterogeneity of pepper varieties. This crop may be grown successfully only if specificity of its mineral nutrition is known.

Identification of Alternaria genus species is a very complicated process which demands broadly designed investigations and studying of great number of properties which together can be considered as satisfying taxonomic criteria. The main objective of these investigations was examining the possibilities of applying the antigenic characteristics of Alternaria spp. phytopathogenic fungi as a taxonomic criterion, as well as introducing the serological methods for their identification. Conducting the examination of Alternaria spp., pathogenic for Apiaceae plants in Serbia, several isolates were obtained and identified as Alternaria radicina, A. petroselini, A. dauci and A. alternata, based on the conventional mycological methods and host range, as well as on molecular detection and partial characterization. The investigation included 12 isolates from plant leaves, seeds and soil which were pathogenic mainly to carrot and parsley and were identified as A. radicina, A. petroselini, A. dauci and A. alternate. Investigated isolates were compared with each other, as well as with standard isolates for the mentioned species (a total of 5 isolates, originating from USA and EU). During the investigation of serological characteristics of Alternaria spp. firstly a polyclonal antiserum was prepared against one isolate from Serbia identified as A. dauci. This antiserum was specific to Alternaria genus while there was no reaction with antigens from other phytopathogenic fungi genera (Fusarium, Rhizoctonia and Agaricus). Antiserum titer, determined by slide agglutination test, was 1/32. Antigenic characteristics of Alternaria genus fungi were examined by Electro-Blot-Immunoassay serological method (EBIA, Western blot), i.e. their protein profiles were compared. Investigated Alternaria spp. isolates showed different protein band profiles in gel and on nitrocellulose paper, and the observed differences were in complete correlation with the results of the previous identification. All investigated isolates, both domestic and the standards, were similar to each other, and they could be correctly identified to the species level using EBIA. Besides grouping to the species level, antigenic characteristics indicated similarities and differences among the isolates within the same and different species, showing their complex relationships which properly reflect their diversity in nature. In all the previous investigations of Alternaria genus fungi up to now, there have been no data about their serological characteristics as possible taxonomic criteria. Introduction of this group of characteristics represents an important contribution both to the taxonomy and implementation of fast and accurate methods of phytopathogenic fungi identification.

The objective of this study was to determine genotype influences on pedunculate oak's leaf traits: leaf area, specific leaf area (leaf area per unit of leaf mass), concentration of photosynthetic pigments, rates of photosynthesis and respiration, and nutrient concentrations (nitrogen phosphorus, potassium, calcium, and sodium). Leaf samples were taken from seventeen Q. robur genotypes originating from clonal seed orchard Banov Brod (Srem, Vojvodina, Serbia). Leaf area of the studied genotypes ranged from 248.4 to 628.8 cm2, SLA from 109.4 to 160.7 cm2 dry matter-1, rates of photosynthesis and respiration from 6.98 to 20.32 and from 6.73 to 14.65 µmol O2 m-2 s-1, respectively. The leaves of genotype 35 contained the highest concentration of photosynthetic pigments, while the lowest were recorded in genotype 29. The following pattern of nutrient concentrations was obtained for the studied genotypes: N>Ca>K>P>Na. Genotype variability of P K, Ca, and Na concentrations was more pronounced when compared with nitrogen. Estimated quantitative differences are the consequence of interaction of certain genotype and common environmental conditions for all trees. These results will provide information on intraspecific variation of the studied leaf characteristics.

Sugar beet root rot has severely occurred in our country recently, especially in localities of Pazova, Pećinci, Ruma, Sremska Mitrovica and Šid. From diseased roots as well as from soil collected from the localities where decay occurred, fungal isolates were obtained by bait plant method. Based on their characteristics, they were identified as multinucleate Rhizoctonia sp. During the year of 2004 in Mitrosrem trial field T-11, where the presence of multinucleate Rhizoctonia sp. was confirmed, an experiment under the coordination of Committee for Acknowledgement and Registration of New Cultivars in our country was conducted in order to determine cultivars' tolerance, i.e. their susceptibility and possibility for growing on infested fields. Six cultivars of sugar beet, Laetitia (as standard) and five new ones were included in the investigation. The trial was conducted in accordance with the established and accepted method (Ministry of Agriculture, Forestry and Water Resources, Republic of Serbia). Susceptibility of investigated cultivars was evaluated according to significant production characteristics root yield, sugar content, corrected sugar content, thick juice Q, molasses sugar, content of K, Na and amino-N, polarized sugar yield and white sugar yield, as it was recommended by the method. Conducted investigations have revealed that tested sugar beet cultivars showed different reactions to natural infection with multinucleate Rhizoctonia sp. Concerning root yield as the most important agricultural characteristic, statistically significantly higher yield was obtained with the cultivar under code mark 5 (61.120 kg/ha) whereas the cultivar marked under code 6 had significantly lower yield comparing to the standard (38.100 kg/ha).

Variability within R. pseudoacacia species represents an important factor in selection of fast-growing genotypes. Therefore, it is important to identify superior individuals according to their anatomical and physiological traits. This paper presents the results of a study of genotype variability of the main leaf anatomical (frequency, length and width of stomata, leaflet thickness among veins, leaflet thickness on the main vein, mesophyll thickness, length and width of vascular bundle of main vein) and physiological (leaf area, photosynthetic pigments content and content of N P, K, Ca, Na) parameters among five clones of Robinia pseudoacacia L. Significant interclonal variations were observed in the investigated parameters. Clone R-56 had the highest N, P, and K concentrations, the largest mesophyll volume and the highest pigment concentration. We concluded that the clone R-56, although without a remarkable leaf area, possesses the ability for high photosynthetic production. The results are going to be used in further work on selection.

Most of the Lathyrus species of the Vojvodina Province arc cultivated for fodder. They are protein-containing herbs which easily recover after grazing. Some perennial species survive in grassland communities for ten years or more. Certain species are important melliferous plants. In the Vojvodina Province, they inhabit different habitats like forests and grasslands, dry and wet sites, thus showing a wide distribution range. Besides their floristic and vegetation aspects, their role as green and dry fodder crops should be emphasized.

The objective of this study was to determine genotype variability of leaf trichome and stoma characteristics. Leaves were sampled from seventeen pedunculate oak (Quercus robur L) genotypes originating from clonal seed orchard Banov Brod (Srem, the Vojvodina Province). The pedunculate oak has hypostomatal leaves. Statistically significant differences were found for the dimensions and density of stomata. Genotype variability of stomatal dimensions was less pronounced in comparison with their density (CV = 8.88%). Stomata number ranged from 530 to 791 per mm2 of leaf area; genotypes 18 and 25 could be distinguished from the others for the highest stomata number per leaf unit area, genotype 35 for the lowest number. In all genotypes, only solitary eglandular trichomes were observed on the adaxial leaf surface while both solitary eglandular and uniseriate glandular hairs were present on the abaxial surface. Single glandular trichomes were observed in all genotypes, while some of them were characterized by the presence of two (genotypes 4, 5, 6, 16, 22, 25, 28, 29, 30, 35, 38, 40, and 85) or three (genotypes 16, 25, 35) hairs joined by their basal cells.

The Lathyrus species are wild relatives of cultivated peas. Results of morphological, anatomical and physiological analyses of Lathyrus latifolius L. are presented in this paper. Certain measured parameters and observed morphological characteristics are not in agreement with available literature data, whereas no reference to the winged stem width, length of inflorescence pedicle, calyx length and leaflet index can be found. Two forms, f rotundifolium RCHB and f. latifolius BECK have been determined. Leaflets are amphystomatic, with anisocytic stomata present in almost equal number on both epidermises, dorsoventral, with one-layered palisade and many-layered spongy tissue. Stem in transverse section is rotund to oval with two long lateral wing-like expansions and cortical bundles. Mineral element analysis shows that the highest N, P and K concentrations were obtained with the flower while Ca and Na with the leaf. Leaf pigment content was higher than stem content while net photosynthesis rate was twice as high as respiration rate.

This study was carried out in order to identify the major viruses infecting pumpkins (Cucurbita pepo)grown in Serbia. Leaf samples from virus-infected pumpkin plants were collected in mid-July 2001. Naked-seeded and hulled oil pumpkins, patty pan, zucchini and summer squash from three different locations were included (Table 1). Virus-infected plants showed different symptoms (Table 2 and Figures 1-4). Due to the great variability of the symptoms, the causal viruses could not be fully and precisely determined by visual examination only. The infected samples were tested by the biotest, as well as by two serological methods, ELISA and EBIA. Polyclonal antibodies raised against cucumber mosaic cucumovirus (CMV), zucchini yellow mosaic potyvirus (ZYMV), watermelon mosaic potyvirus 1 (WMV-1), watermelon mosaic potyvirus 2 (WMV-2) and squash mosaic comovirus (SqMV) were used. In each of the 50 collected samples one or two viruses were detected (Tables 3 and 4). The most prevalent viruses infecting pumpkins were ZYMV (62%) and CMV (58%). WMV-2 was extremely rare.

Photosynthesis, transpiration, water use efficiency (WUE) and biomass production have been investigated in nine black poplar clones (section Aigeiros) in three field experiments. Eastern cottonwood clones (Populus deltoides) had the highest net photosynthesis and water use efficiency. European black poplar clones had the highest transpiration intensity. Correlation analysis showed that net photosynthesis was in a high positive correlation with biomass. Medium negative correlations existed between WUE and net photosynthesis, transpiration and biomass and WUE and biomass. The study showed a pronounced interclonal variability of the physiological and growth characters under study.