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Dianthus giganteiformis subsp. kladovanus is an endemic, endangered, horticulturally appealing perennial plant that can be used for the revegetation of sand dunes of the Danube region. The appropriate method for its effective production is micropropagation. For this reason, the experiments were conducted in order to establish an efficient protocol for the micropropagation of this subspecies. The sterile culture was initiated from seeds collected in situ and the germination percentage was high (88%). According to the results obtained in this study, the multiplication phase should be performed on an MS medium enriched with 0.1 mg/L BAP and 0.1 mg/L NAA. The concentration of MS salts significantly influenced rooting, and higher rooting percentages were obtained on reduced MS media (91.7 - 95%) than on MS media (73.4 - 76.7%). The addition of NAA slightly increased rooting percentage (up to 95%). Obtained microplants were successfully acclimatized (83.3%) in a substrate composed of peat and sand (1: 1; v/v). Using the protocol presented in this paper, the efficient propagation of D. giganteiformis spp. kladovanus can be achieved for rapid plant production aimed at revegetation, biodiversity protection and floricultural production of this species. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 43007]

The review of recent researches regarding the in vitro culture of 30 endangered Dianthus taxa is presented in this paper. Various in vitro protocols developed for selected rare and threatened Dianthus taxa are analysed in order to provide a useful synthesis of the data obtained with the main principles, techniques and recommendations for futher research and practice. The recapitulated data presented in this review can be used as a tool for the micropropagation of other endangered Dianthus taxa, enabling their propagation and obtaining a sufficient amount of plants for reintroduction. In addition, the obtained results represent the basis for ex situ conservation of the investigated taxa, especially for medium-term and long-term conservation (cryopreservation). [Projekat Ministarstva nauke Republike Srbije, br. 43007]

The aim of this study was to determine the possibility of micropropagation of the medicinal plant A. millefolium on half-strength MS medium and ex vitro rooting and acclimatization of the obtained microshoots in hydroculture in order to establish an efficient production method. Two explant types were used: basal and terminal cuttings, and better results were achieved when terminal cuttings were used. The development of shoots in the multiplication phase was successful with a regeneration percentage of 100%. Ex vitro rooting in a modified Hoagland nutrient solution was successful (83%), but the percentage of in vitro rooting on half-strength MS medium without hormones was higher (95%). However, bearing in mind that mass production of A. millefolium is more efficient when the phase of in vitro rooting is excluded, this method could be recommended for commercial propagation of this medicinal plant. It is necessary to conduct additional research in order to optimize the composition, EC and pH value of the hydroponic nutrient solution. [Projekat Ministarstva nauke Republike Srbije, br. 43007]

Some heavy metals such as Zn are essential micronutrients for plants. However, in a high concentration in soils they could cause repression of growth with toxicity symptoms. It is therefore very important to investigate the species that are tolerant to high concentration of zinc which have the ability to survive on soils contaminated with heavy metals. This paper presents an investigation of the effect of elevated Zn concentrations on the germination and seedling growth of the invasive tree species Ailanthus altissima (Swingle) Mill., aimed at a better understanding of its adaptation ability to heavy metal stress and potential use in phytoremediation. Seeds of Ailanthus altissima were treated with Zn concentrations of 25, 100 and 250 μM in form of zinc sulfate. After germination, the seedlings at the stage of first leaf development were transferred into a growing chamber in the hydroponic system where zinc sulfate was added in the concentrations of 100, 250 and 500 μM. The results showed that Zn treatments, including the highest concentration, have caused a reduction in seed germination parameters. Considering the hypocotyl and radicle length, there was no significant statistical difference among the treatments, but further growth of young seedlings in hydroponics under high concentrations of Zn, cause an inhibition of the root system growth and repress development of assimilating organs. Seeds and seedlings of A. altissima are tolerant to elevated Zn concentrations at early stages of development. However, later on with leaves development, the inhibitory effect of the strongest concentrations is expressed. [Projekat Ministarstva nauke Republike Srbije, br. 43007: Studying climate change and its influence on the environment: impacts, adaptation and mitigation]

In this paper are presented the analyzes of some morphometric properties, leaves area stomata density and the intensity of leaves transpiration of white poplar, Populus alba L. and canadian poplar, Populus x canadensis Moench ‘I 214’ in populations at (1) flooded (wet) and (2) unflooded (dry) habitats on the Ada Ciganlija river island during the growing season. Six trees of each species from both habitats were selected, with similar height, age and physiological condition. The morphometric analysis of the analysed poplar species show that the type of habitat did not influence tree height and trunk as well as the leaves area. However, crown width and trunk diameter were greater in the wetter habitat. It was found that the intensity of transpiration of Populus x canadensis ‘I 214’ trees had higher average values (0,73 gH2Odmˉ²hˉ¹) than white poplar (0,68 gH2Odm ˉ²hˉ¹). Transpiration of both taxa was more intensive on the drier than on the flooded habitats. By analyzing the number and size of stomata on leaves of the investigated Populus x canadensis ‘I 214’ trees, it was found that stomata are more numerous but of smaller size on the leaves from drier habitats. It could be concluded that both species could have impact on microclimate conditions by increasing air moisture content and decreasing air temperature but Canadian comparing to white poplar, slightly greater. Increasing air temperature is a consequence of evident global climate change. Through transpiration plants reduce summer air temperature indirectly, by increasing its relative humidity. [Projekat Ministarstva nauke Republike Srbije, br. 43007: Studying climate change and its influence on the environment: impacts, adaptation and mitigation]

The study deals with the influence of growth regulators on the germination of Judas tree (Cercis siliquastrum L.) seed which is double dormant. We simultaneously tested seeds prepared in the conventional procedure: scarification + stratification and scarified seeds treated with phytohormones from the groups of gibberellins, auxin and cytokinins. The results indicate a positive effect of gibberellic acid (GA), as well as some combinations of this phytohormone with others. Recommendations for practice are to combine the conventional procedure with GA. The procedure may shorten the duration of stratification; the application of GA should follow stratification because the temperature of 4°C does not provide growth regulators activity. The study results can serve as the base for easier generative reproduction of this valuable woody ornamental species which could have a wide use in changed climate conditions. [Projekat Ministarstva nauke Republike Srbije, br. 43007: Studying climate change and its influence on the environment: impacts, adaptation and mitigation]

Seeds of sweet acacia (Vachellia farnesiana (L.) Wight & Arn.) were mechanically scarified and treated with concentrated sulfuric acid in order to determine the permeability degree of the seed coat. The obtained results suggest a stronger form of seed coat dormancy that prevents potential invasiveness after introduction. The species is recommended for limited cultivation in outdoor conditions and unlimited use in interior spaces as full size or bonsai trees. [Projekat Ministarstva nauke Republike Srbije, br. 43007: Istraživanje klimatskih promena i njihovog uticaja na životnu sredinu: praćenje uticaja, adaptacija i ublažavanje]

In this study, the effect of concentration of indole-3-butyric acid (IBA) (powder dip), cutting type as well as the time of taking cuttings on the rooting of softwood cuttings of cornelian cherry was examined. Four types of cuttings were used: basal cuttings, terminal cuttings, basal cuttings with 2-year-old wood and terminal cuttings with 2-year-old wood. The obtained results showed that IBA concentration, cutting type and time of collecting have significant effect on rooting. The best results were obtained using 1% IBA and cuttings collected in the second term (in mid-July) had a higher rooting percentage. Terminal cuttings treated with 1% IBA (powder dip) should be used for optimum results. In that case the rooting percentage was very high (over 90%) in both terms of cuttings collection. [Projekat Ministarstva nauke Republike Srbije, br. 43007: Istraživanje klimatskih promena na životnu sredinu: praćenje uticaja, adaptacija i ublažavanje]

The effect of the concentration of MS salts and explant type on D. serotinus rooting and acclimatization was investigated in order to optimize a protocol for the micropropagation of this species. The obtained results showed that explant type as well as the concentration of MS salts had a significant effect on rooting, and the highest rooting rate (85-86,7%) was achieved when culturing single-node cuttings and terminal buds on a half-strength MS medium supplemented with 0,5 mgL-1 NAA. Nevertheless, mean number of roots per explant was higher on the MS media (15,3-18,6) than on the half-strength MS media (11,8-13,4). The best acclimatization rate was obtained in a 4:1 mixture of peat and sand (83,3-86,7%). The explant type from which in vitro plantlets developed had no effect on the acclimatization rate. [Projekat Ministarstva nauke Republike Srbije, br. 43007]

The aim of this study was to investigate the effect of different concentrations of sorbitol on the development of the in vitro culture of D. serotinus in the multiplication phase. The obtained results showed that sorbitol generally had a positive effect, depending on its concentration and explant type. In addition, the presence of sorbitol affected the change of pH value of the media after autoclaving and after 25 days of in vitro culture, which could affect the availability of certain ions to plants. Therefore, the obtained results indicate that sorbitol can be used as an energy source for the in vitro culture of D. serotinus, but this should be further investigated. [Projekat Ministarstva nauke Republike Srbije, br. 43007]

Propagation by cuttings is one of the most successful methods of vegetative propagation of floral crops. In addition to applications in interior decoration, ficuses belong to the group of plants that will potentially be used in green spaces of Belgrade due to global climate changes. In this paper, the possibility of rooting stimulated by adding different concentrations of the indolbytric acid phytohormone was investigated in the commonly cultivated species Ficus benjamina L. and Ficus elastica Roxb.. This is the most commonly used phytohormone in the propagation of ornamental plants due to its stability and stimulation of the rooting process, i.e. its favourable impact on the formation of adventitious roots, their size, number and weight. In this research, the rooting percent of cuttings was 100 % in F. benjamina and 77.66 % in F. elastica. It was found that the highest dose (2 %) of the phytohormone significantly increased all indicators of rooting success in F. benjamina and that the application of weaker concentrations also showed good success. The rooting of F. elastica cuttings was not successful without phytohormones, and the best results were achieved at the phytohormone concentration of 2 %, which increased the dry weight of the roots of this ficus about 4 times. It would be useful to examine higher concentrations of this phytohormone and also some combinations with other rooting stimulators, to be able to make sound recommendations on the optimal dose for the mass production of these ficuses. [Projekat Ministarstva nauke Republike Srbije, br. 43007]

Today, in vitro culture is of the great importance in both scientific investigation of under-researched plant species and plant production. In this paper, a review of development and methods of in vitro culture is presented. The main principles are given and the most commonly used methods are described. Special attention was paid to the propagation of Dianthus spp. Tissue culture of commercially important taxa is described in detail, and the review of propagation of other decorative Dianthus spp. that can be used as ornamental plants is also given. [Projekat Ministarstva nauke Republike Srbije, br. 43007: Istraživanje klimatskih promena na životnu sredinu - praćenje uticaja, adaptacija i ublažavanje]

Two methods of rooting of Zelkova softwood cuttings were analyzed: (1) quick-dip method and (2) contact method - the thin polyethylene film (20 mm) laid directly over the cuttings during the rooting process. The control for contact method was a low tunnel with a thick polyethylene film. One group of cuttings in the contact method was treated with quick-dip (IBA 2,500 μg•mL-1, carrier-ethyl alcohol) during 5 sec, and the other group was treated with water solution of IBA (50 μg•mL-1) in 24-hour treatment. The third group was control - untreated cuttings. The same groups of cuttings were also used in low tunnels. The number and length of primary and secondary roots were measured on rooted cuttings. The results of all treatments show that contact method in combination with water solution of IBA was the best with 92% of rooted cuttings. No significant differences were obtained between this treatment and quick-dip + contact method (85.3%). Rooting of cuttings under low tunnel was significantly lower. In general, contact method was better than low tunnel, disregarding the carrier used. These results recommend the almost unknown contact method in nursery propagation of Zelkova, as an alternative, non-invasive species for the conditions in Serbia.

Relative amounts of nutrients, especially nitrogen, the most abundant macro-element, and also the distribution of ammonium ions in relation to nitrate ions, in the soils of different ecosystems, are determined by many factors. The most important are: temperature, pH of substrate, accumulation of organic matter, presence of allelopathic compounds, degree of oxygenation, etc. The ability of plants to adapt to these variations influences their production of bio-mass, the rate of expansion in different habitats, and the impact on ecosystem and biodiversity. This paper analyzes the impact of different forms of nitrogen (NO3 - and NH4 +) on the growth of seedlings of invasive species Acer negundo L. and Ailanthus altissima (Mill.) Swingle. The results show that nitrogen nutrition only in the form of NH4 + ions significantly affects the reduction in shoot dry weight. Compared to the nutrition with both forms of nitrogen together, aerial parts of Ailanthus altissima were reduced by 62.5%, and leaf area by 66.7%, while Acer negundo seedlings had reduction in dry mass of aboveground part by 89.5%, root by 81.2% and leaf area by 85.8%. Nutrition with nitrate form of nitrogen led to a proportionally small, but statistically significant decrease in dry mass of aboveground parts and roots as well as leaf area of Acer negundo, while in Ailanthus altissima seedlings, it was only the mass reduction of aboveground parts that was significantly influenced, so it can be assumed that this species is more resistant to the lack of both forms of nitrogen. The fact that both species produced significantly more biomass when nitrogen was present in both forms may be important in controlling the spread of alien species, or in their potential use in phytoremediation.

Invasive species Aster lanceolatus grows on moist habitats on the whole territory of Serbia. In Belgrade, this species is recorded with a higher degree of presence at a number of localities. With the aim to investigate the community in which this species is dominant, the wide area of Serbia was researched, and 8 localities on the territory of Belgrade were chosen for the analysis of the community. Floristic structure of the community was determined by the standard Braun-Blanquet method (1964), phytogeographical analysis was performed according to Gajić (1980, 1984), and determination of life forms according to Raunkier (Ellenberg, Mueller-Dombois, 1967). pH soil analysis and electric conductivity (EC) were performed at all investigated localities. It was established that the community dominates the moist habitats of Belgrade. It is composed of 104 species and among them Aster lanceolatus Willd., Cichorium intybus L., Agropyrum repens (L.) Beauv., Calystegia sepium (L.) R. Br., Cirsium arvense (L.) Scop., Symphytum officinale L. and Rumex obtusifolius L. are the most frequent. In relation to life forms, the community has hemicriptophytes character, and in relation to phytogeography Euroasian and Middle Europaean floral elements are dominant, with a high presence of cosmopolitan and adventive floral elements. On the locialities Veliko Ratno ostrvo (island) and Makiš, EC values point to the fact that the amount of nutrient in the soil is higher than at other localities.

The Small-winged wingnut is a 12 to 20 metres tall, deciduous and fast growing tree with large substantial branches that spread as wide as the tree is tall. The 15 to 30 cm long winged fruit catkins, which turn brown in the autumn, are suspended below the branches. The species is not described by domestic authors in Serbia. The seed was introduced from Sofia (from the Arboretum of the Forestry University of Sofia, Bulgaria - Lesotehničeski universitet, Sofija), and subjected to classical stratification and naked stratification during the period of 1 and 2 months. Germination capacity varied among the treatments. The largest number of germinated seeds was observed in the shorter stratifications, (1 month) the classical (56.5%) and the naked (51.0%) with no significant difference. The values of real germination of all treatments were between 69-88%. High value of RG, compared to GC, indicated that more than 40% of the seeds were empty. However, the results of the control as well as other parameters of seed germination clearly point to the fact that practically no deep embryo dormancy was observed, but the seed is recalcitrant and microbiotic. The results indicate a non-invasive character of the species in terms of reproductive potential.

The old flotation tailings of the Bor copper mine have not been reclaimed for several decades, although it is a serious threat to the environment, especially to some parts of the town. To date, there have been no efficacious attempts of solving the problem by indirect rehabilitation, only several cases of direct reclamation. This paper presents some results of the experiment established on a part of the tailings in the vicinity of the town, where various variants of meliorated and sterile substrates were applied in the biological reclamation with several tree and grass species. The analysis shows that, in the rehabilitation of sterile substrate of the copper mine, it is possible to grow several woody species. The best results were achieved by the species that were planted in the fertile soil layer on the sterile copper mine substrate, and on the mixture of soil and waste. Among the woody species, Robinia pseudoaccacia, Fraxinus excelsior and Acer pseudoplatanus showed the best survival percent, growth, and physiological vitality and the poorest were spruce and common oak.

The species Aster lanceolatus occupies a significant position in the world and European lists of invasive species. Its spreading potential is a hazardous factor to the biodiversity in many countries. There are no relevant data on the wider proportion of this species in the area of Belgrade. The sites of Aster lanceolatus are annual or pioneer communities along the water courses, abandoned and neglected areas, forest margins, moist meadows. The study areas are located near a choice of water courses in Belgrade. The aim of the study was to assess the species ecology and population density, synecological interrelationships among the coenobionts of the communities in which it occurs, and also to map its the habitats. The study of population density was performed on the supplemented and partially modified 'CPS SKEW' form, applied in West European countries, by the principle of squares. The species was determined by standard floristic method, and the species location by GPS system. It was concluded that Aster lanceolatus was dominant and wild at all study sites. The individuals and populations are especially numerous on the river islands Ada Ciganlija and Veliko Ratno Ostrvo, along the stream Kumodršaki Potok and the Danube left bank, where the number of individuals per squares is above 1300 and the degree of coverage is 100%. Its spreading potential is conditioned by the species biology, and the expansiveness by climate changes, anthropogenic impacts and the competitive interrelationships.

It is known that invasive plant species, as the species which most often spread and suppress the native species, form stable populations and become dominant firstly by occupying the sites of urban areas, and later on by continuing their invasion to the neighbouring suburban and rural areas. This paper presents the research of biological and ecological characters of Elaeagnus umbellata Thunb., one of the potential invasive species. The phenological observation of this species yield abundance and periodicity and the biometric analysis of fruits and seeds point to a high quality of its generative reproductive material. The analysis of seed dormancy of this species in our conditions, as the significant factor of the control of potential invasiveness, shows its double dormancy and its elimination requires combined chemical treatments and several months of stratification. The study of mechanisms of autumn olive dormancy breaking (overcoming the reproductive barrier) and seed dispersion (overcoming the dispersion barrier) is very significant for the forecast of further dispersion of this species.

In nursery stock production of some ornamental woody plants the appearance of spontaneous variability was identified in the form of atypical pigmentation of leaves (albinism, variegated, red colored), leaves shape (jaggy) and dwarfs. Mutated plants with variegated leaves were observed among hybrid plane (Platanus x acerifolia (Ait.) Willd.), Siberian elm (Ulmus pumila L.), laurel cherry (Prunus laurocerasus L.) and Lawson false-cypress (Chamaecyparis lawsoniana (Murr.) Parl.) Seedlings. The type of variegation and frequency were analyzed. Among plane tree and Siberian elm seedlings there were observed red colored leaves. Atypical, jaggy shaped leaves were found among laurel cherry seedlings. Dwarf growth was identified at Siberian elm and birch (Betula pendula Roth.) where also found fruits at one year seedling. There were not significant differences in some morphological and physiological properties in plane tree seedlings with various pigmented leaves. .

The aim of the experiment was to determine the optimal presowing treat­ment for breaking seed dormancy of Japanese raisin tree (Hovenia dulcis Thunb.), a very rare exotic species introduced to the Mediterranean parts of Serbia and Mon­tenegro. Three pretreatments are applied: mechanical scarification and chemical scarification (conc. H2SO4) lasting for 5 and 120 minutes. The best treatment was the longer chemical scarification, which confirmed the dormancy of the seedcoat.

The usability of seeds for the production of seedlings, as well as the utilisation potential of seeds for natural regeneration was assessed by the comparative analysis of seed germination from the cones of different ages of three species with partial serotiny (P. halepensis Mill., Cupressus sempervirens L., Cupressus arizonica Greene). In cypress, serotiny is not so expressed as to be a reserve for extraordinary situations (fire). Fouryearold Aleppo pine cones should be collected for production purposes. Serotinous cones up to ten years old are efficient for natural regeneration of Aleppo pine forest after fire.

The results of the influence of main macronutrients (N, P, and K) on growth and development of spruce (Picea abies L. Karst) one-year old seedlings are presented. They were grown in containers, in nursery conditions, on four different substrates. There is a good influence on biogenous element contents, height, root collar diameter, needle length and mass, root mass as well as physiological vitality of spruce seedlings. It was observed that the effect of nutrition depends also on the type of substrate.