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Fast growing woody plants represent effective tools for cadmium (Cd) extraction during remediation of low to medium Cd contaminated soils. Poplars are good candidates for this task because of their rapid growth rate, high biomass yield, and adaptability, as well as the availability of well-characterized clones/ genotypes with various anatomical and physiological traits. The present study evaluates the potential of Populus deltoides (clone B-81) and Populus × euramericana (clone Pannonia) for phytoremediation of Cd contamination in soil. Poplar clones were analyzed for (1) plant growth response to Cd contamination, (2) Cd accumulation, translocation, and partitioning between plant organs, and (3) morphological, anatomical and physiological responses to Cd stress as a function of biomass production. Plants were cultivated in soil moderately contaminated with Cd (8.14 mg kg-1 soil) under semi-controlled conditions for six weeks. Our results suggest that P. × euramericana and P. deltoides clones respond differently to Cd contamination. Biomass production and morphological characteristics were more negatively affected in P. × euramericana than in P. deltoides plants. However, most examined leaf structural parameters were not significantly affected by Cd. In most cases, photosynthetic characteristics and gas exchange parameters were affected by Cd treatment, but the levels and patterns of changes depended on the clone. High tolerance to applied Cd levels, as estimated by the tolerance index, was observed in both clones, but was higher in P. deltoides than P. × euramericana (82.2 vs. 66.5, respectively). We suspect that the higher tolerance to Cd toxicity observed in P. deltoides could be related to unchanged proline content and undisturbed nitrogen metabolism. Following treatment, 58.0 and 46.7% of the total Cd content was accumulated in the roots of P. × euramericana and P. deltoides, respectively, with the remainder in the stems (18.2 and 39.9%) and leaves (23.8 and 13.4%). In summary, P. deltoides displayed better phytoextraction performance under Cd exposure than P. × euramericana, suggesting its potential not only for Cd phytostabilization, but also phytoextraction projects.

A large number of macrophytes, often in dense populations, have developed on the Grlište Reservoir, Serbia over a period of 15 years. Fast development of vegetation is a consequence of anthropogenic impact in lake management. The methodology used in this research covered 100% of the water body, including all areas with or without aquatic plants. The results indicate that plant communities are still in the early phase of development. This leaves space for future development of competitor macrophyte species (Najas marina, Eleocharis palustris, Typha latifolia, Typha angustifolia, Phragmites australis, etc.) capable of endangering stability of the lake, which will tend toward eutrophication.

Good photosynthetic features and a favorable water regimes of woody plants improve their survival and remediation potential under unfavorable ecological conditions. Accordingly, we here present results of testing plant tolerance of Pb, Cd, Ni, and diesel fuel based on gas exchange parameters and WUE of four poplar and two willow clones grown in a greenhouse on soil culture. Photosynthesis and transpiration of plants grown on soils with individually applied heavy metals decreased significantly, but this was less obvious in the case of Cd treatment. A heavy metal mixture in the soil induced significant reduction in photosynthesis (by more than 50%). Diesel fuel as the only pollutant in soil caused very strong and significant inhibition of photosynthesis and transpiration of willow clones. The results indicate genotypic specificity of all investigated physiological parameters and mark poplar clones as very useful in phytoextraction technology for the bio-cleaning of chemically polluted soils.

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.

An anatomical study of adventitious roots of three Salix clones, ‘B-44’, ‘SV068’ and ‘SM4041’, treated with 3 and 6 mg Cd kg-1 dry weight in soil was performed in a greenhouse experiment. The aim was to analyze the anatomical characteristics of roots in response to pollution by cadmium and to assess the potential application of anatomical and hydraulic characteristics in the selection of the most suitable Salix clones for phytostabilization of pollutants in soils. Anatomical parameters measured in this study included root cross-sectional area, root diameter, the proportion of periderm, secondary phloem (cortex) and wood (secondary and primary xylem), and parameters of the vessels (lumen area, diameter and frequency). Based on the measurements of individual vessel lumens and the number of vessels, the theoretical hydraulic conductivity (kh) of roots was calculated. The effects of applied Cd concentrations on root traits were studied in clones and control plants. Following treatments with both Cd concentrations, plants of clone ‘B-44’ had the highest values of most parameters and significantly higher kh in comparison with control samples due to the significantly larger root cross-sectional area and lumen area of vessels. It was concluded that these characteristics can serve for effective evaluation and selection of studied clones for remediation of sites contaminated with cadmium.

White poplar is a key species in wood production and afforestation, but also very important for biodiversity preservation and habitat improvement. Vegetative propagation from hardwood cuttings is the most desirable method of white poplar breeding. The present research analyzed the effect of various technological treatments on four white poplar clones. Selected treatments were powder formulations of indole butyric acid (IBA) and foliar treatment with urea. The variability of 14 morphometric characteristics on the rooting of cuttings was analyzed, as well as relationships between them. Differences in analyzed morphometric characteristics depended on genotype, while the effect of the examined technological treatments was detected only by Fisher’s least significant difference (LSD) test. Significant variability between genotypes was found for traits describing rooting at the basal cut (R0 and R0p), the number of leaves (LN), the total number of roots (TRN), and cutting survival in the first part of the growing season (SURV07). Application of IBA had significant stimulating effects on rooting at the lower part of cuttings (R05) compared to controls. Variability between genotypes after foliar treatment with urea was not detected. The examined parameters were grouped into 5 groups by principal component analysis, where shoot traits and traits that describe rooting at the basal cut were in the same group with total number of roots, and cutting survival (SURV07) was in a separate group. These results suggest a need for further testing of the characteristics of hardwood cuttings in white poplars. More efficient clone technology is needed, using auxins and/or nitrogen fertilization designed to suit the specific requirements of particular clones. [Projects of the Serbian Ministry of Education, Science and Technological Development, Grant no. 43007: Studying climate change and its influence on the environment: impacts, adaptation and mitigation and Grant. no 43002: Biosensing Technology and Global Systems for Continuous Research and Integrated Management of Ecosystems]

Two half-sib lines of Turkey oak (Quercus cerris L.) (C1 and C2) were subjected to different treatments in semi-controlled conditions: optimal soil moisture - control (K), drought followed by recovery after the restoration of the optimal soil moisture (T1) and the treatment of constant drought (T2). Changes in the physiological parameters related to the process of photosynthesis were examined in correlation with the applied treatments. Treatment T2 was influenced to a significant reduction in the intensity of photosynthesis, stomatal conductance and instantaneous water use efficiency, as well as to a significant increase in the intercellular CO2 concentration in both half-sib lines. In relation to control, treatment T2 did not lead to a significant variation in the maximum photochemical efficiency in the examined half-sib lines. In treatment T1, the second half-sib line (C2) showed better ability to recover the intensity of photosynthesis and stomatal conductance after re-watering, while using the same treatment before recovery, water was used more efficiently compared to the first half-sib line (C1). The results of the study indicate specific adaptive predispositions of the examined half-sib lines in relation to drought stress and recovery. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III 43002: Biosensing Technology and Global System for Continuous Research and Integrated Management of Ecosystems]

are valuable source of vitamins, minerals and fibers important for healthy human nutrition. However, an increased level of heavy metals in vegetables has been noticed in recent years. This study was conducted with an aim to analyze content of heavy metals, cadmium (Cd), lead (Pb), and chromium (Cr) in 11 vegetable species which are the most common in human diet. Vegetables were collected from three green markets (Limanska, Futoška and Riblja pijaca) in Novi Sad, during September and October, from 2009 to 2011. Heavy metal contents were analyzed in edible parts of tomato, potato, spinach, onion, beetroot, parsley, parsnip, carrot, cauliflower, pepper and broccoli using atomic absorption spectrophotometer (Varian, AAS 240FS). The results showed statistically significant differences in element concentrations among analyzed vegetables. In general, the highest metal pollution was observed in the year of 2011. Spinach was found to contain the highest metals content - 0.89 μg/g for Cd, 5.81 μg/g for Pb, and 3.67 μg/g for Cr. According to Serbian official regulations, 18.18% of all analyzed species exceeded maximum permissible level for Cd, 9.09% for Pb, while for Cr these limits are not defined. Elevated content of heavy metals in vegetables might be related to soil contamination, atmospheric depositions during transportation and marketing. Thus, a continuous monitoring of vegetables on markets should be performed in order to prevent potential health risks to consumers.

Three willow species (Salix alba, Salix matsudana and Salix nigra) were exposed to very high cadmium (Cd) concentrations in order to define some physiological traits related to high biomass production. Plants were grown hydroponically under semi-controlled conditions (greenhouse). It was assumed that leaves accumulate different amounts of Cd in relation to their age due to the specific occurrence of symptoms generated by Cd accumulation. The rate of photosynthesis and concentration of photosynthetic pigments in young and old leaves was correlated with biomass production in order to ascertain their significance as indicators of plant performance at sites contaminated with Cd. Changes in the photosynthetic parameters induced by treatments depended on the concentration of Cd in the nutrient solution, the species of willow and leaf age. Fv/Fm ratios were not considerably changed in treated plants, indicating preserved activity of PSII. According to results presented in this work, the Fv/Fm ratio was a less sensitive indicator of Cd stress in willows than the rate of photosynthesis and pigment concentration. High tolerance to applied treatments estimated on the basis of biomass production of S. nigra and S. matsudana irrespective of Cd concentration in the growth substrate might indicate their potential in the reclamation of Cd-contaminated sites. [Projekat Ministarstva nauke Republike Srbije, br. No. III 043007]

The concentrations of Cu and Zn were measured in shoots of plants Phragmites australis (Cav.) Trin ex Steud., Typha latifolia L. and Typha angustifolia L. at four locations in the area Bardača (Necik - neglected fishpond, Lug - fishpond used for recreation activities, Sinjak - active fishpond and Matura - river connected to some of the fishponds). In all these types of water bodies, Zn and Cu concentrations were the highest in young plants (May-June) and then declined until the end of the season, especially in September. Phragmites australis has accumulated higher amounts of Zn than Typha latifolia and Typha angustifolia, whereas for Cu the difference between species was not so clear. In relation to the site, the largest concentrations of Zn and Cu were recorded in plants from the sites Sinjak and Matura, followed by Necik and Lug respectively. Such site specific differences are related to specific ecological conditions at each habitat.

The heavy metal (cadmium, lead, nickel, chromium) and mineral element (potassium, phosphorus, calcium, magnesium) levels in edible parts of tomato, potato, spinach, beetroot, parsley, parsnip, carrot, cauliflower, pepper and broccoli were determined by atomic absorption spectrophotometry. Six samples for each species originating from different localities were collected from green markets. The heavy metal concentrations ranged from calcium > phosphorus > magnesium. The highest mean levels of the heavy metals, as well as of potassium, calcium and magnesium, were found in spinach. A large number of samples containing high levels of toxic heavy metals, especially of cadmium and lead, impose the necessity for strict regulative guidelines concerning individual vegetable crops production, harvest, handling and storing, in order to diminish possibility of contamination.

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.

The paper presents the impact of periodic soil drought on physiological parameters important for bioproductivity of mountain beech populations. The investigated forest population was located near Fruška gora mountain peak, where water runs off quickly, and consequently lack of soil humidity develops very often. Decreasing trends of photosynthesis, transpiration, water use efficiency and stomatal conductance (gs) during the growing season were evident, in correlation with a shortage of precipitation. Diurnally, photosynthesis of beech leaves showed rhythmical changes. It was the most intensive in the morning, then decreased between noon and 1 pm, and increased again during early afternoon. High leaf temperature and water deficit in the deeper soil layers caused a decreasing trend in photosynthesis and daily rhythmic changes of the transpiration rate and water use efficiency. Although surface soil water capacity did not show a significant decreasing trend from July to September, a lack of precipitation was observed, which probably caused a lack of moisture in deeper soil layers, resulting in a decline in photosynthesis and transpiration. Physiological status, linked to primary photosynthetic productivity of forests, could be a significant indicator of environmental conditions and trends in climate changes.

Rapid industrialization, urbanization, and mine tailings runoff are the main sources of heavy metal contamination of agricultural land, which has become one of the major constraints to crop growth and productivity. Finding appropriate solutions to protect plants and agricultural land from heavy metal pollution/harmful effects is important for sustainable development. Phytoremediation and plant growth-promoting rhizobacteria (PGPR) are promising methods for this purpose, which both heavily rely on an appropriate understanding of the anatomical structure of plants. Specialized anatomical features, such as those of epidermis and endodermis and changes in the root vascular tissue, are often associated with heavy metal tolerance in legumes. This review emphasizes the uptake and transport of heavy metals by legume plants that can be used to enhance soil detoxification by phytoremediation processes. Moreover, the review also focuses on the role of rhizospheric organisms in the facilitation of heavy metal uptake, the various mechanisms of enhancing the availability of heavy metals in the rhizosphere, the genetic diversity, and the microbial genera involved in these processes. The information presented here can be exploited for improving the growth and productivity of legume plants in metal-prone soils.

Continuous monitoring of heavy metal content in vegetables is of high priority for population nutrition control, as well as risk assessment for human health. The chemical composition of plants is a reliable indicator of their contamination by hazardous substances accumulated in the environment as a consequence of inadequately applied agro-technology. The main goal of this study was to examine the quality of vegetables that reach consumer markets as a function of growth location. Samples of 11 of the most common vegetable species used in the human diet were collected during a 4-year survey. Vegetables originated from local farm producers who cultivated them at different locations in Vojvodina Province, Serbia. Many vegetable samples contained disturbingly high levels of the investigated metals: cadmium, lead, nickel, and chromium. The plant species with the highest Cd accumulation was spinach, where Cd leaves exceeded the maximum permissible concentrations (MPCs) in more than half of the analyzed samples from different localities (54%). Pb concentrations in spinach were also higher than MPC values (according to Serbian law 3.0 μg/g) in 46% of all analyzed samples. Results showed that Cr levels in all tested vegetable species were below MPC values recommended by the FAO/WHO organization. The largest chromium accumulator was spinach, with average values of 2.3 μg/g, followed by beetroot and parsnips with an average concentration of 1.4 μg/g. The highest average content of Ni in all analyzed vegetable species was also recorded in spinach leaves, with an average value of 2.2 μg/g, followed by broccoli (1.7 μg/g) and tomatoes (1.5 μg/g).

Over the past few years, significant efforts have been made to decrease the effects of drought stress on plant productivity and quality. We propose that fullerenol nanoparticles (FNPs, molecular formula C60(OH)24) may help alleviate drought stress by serving as an additional intercellular water supply. Specifically, FNPs are able to penetrate plant leaf and root tissues, where they bind water in various cell compartments. This hydroscopic activity suggests that FNPs could be beneficial in plants. The aim of the present study was to analyse the influence of FNPs on sugar beet plants exposed to drought stress. Our results indicate that intracellular water metabolism can be modified by foliar application of FNPs in drought exposed plants. Drought stress induced a significant increase in the compatible osmolyte proline in both the leaves and roots of control plants, but not in FNP treated plants. These results indicate that FNPs could act as intracellular binders of water, creating an additional water reserve, and enabling adaptation to drought stress. Moreover, analysis of plant antioxidant enzyme activities (CAT, APx and GPx), MDA and GSH content indicate that fullerenol foliar application could have some beneficial effect on alleviating oxidative effects of drought stress, depending on the concentration of nanoparticles applied. Although further studies are necessary to elucidate the biochemical impact of FNPs on plants; the present results could directly impact agricultural practice, where available water supplies are often a limiting factor in plant bioproductivity., Competing Interests: The authors have declared that no competing interests exist.