Dragana Skocajic

The effects of iron deficiency on lead accumulation in Ailanthus altissima (Mill.) Swingle seedlings.

Understanding the effects of root Fe deficiency on the uptake and translocation of toxic metals can be important for improving the phytoremediation strategies of polluted soils. The present study investigated how Fe nutritional status affects the uptake and root-to-shoot-translocation of Pb in hydroponically grown seedlings of (Mill.) Swingle. The interactions of Fe deficiency and Pb were assessed by measuring the root Fe(III) reductase activity, carboxylic acids concentration in root exudates, root and shoot biomass, and accumulation of Pb and other metals (Fe, Zn, Mn, and Cu) in roots and leaves of Fe-sufficient (+Fe) and Fe-deficient (-Fe) plants. The results indicate that Fe deficiency induced 18-fold higher Fe(III) reductase activity in roots compared with +Fe plants, which was followed by increased root exudation of citric acid (28.2 ± 1.39 in +Fe and 498 ± 256.4 μmol g DW 2 h in -Fe plants). Iron deficiency also induces a significant decrease of root and shoot dry weight compared with the control +Fe plants, whereas 2-wk Pb (20 μM) treatment did not influence root and shoot growth. Iron-sufficient plants accumulated more Pb (56.8 ± 17.29 μg g) in leaves than -Fe plants (21.5 ± 8.10 μg g). Two weeks of exposure to Pb significantly decreased Fe(III) reductase activity and accumulation of Fe, Zn, and Mn in the roots of -Fe plants. It is hypothesized that 2 wk of root exposure to Pb blocks functioning of a specific Fe transport system activated under Fe deficiency.

Asteretum lanceolati - xenospontaneous community on wet and riparian habitat.

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 lo- calities on the territory of Belgrade were chosen for the analysis of the community. Floristic structure of the community was determined by the standard Braun-Blan- quet method (1964), phytogeographical analysis was performed according to Gajic (1980, 1984), and determination of life forms according to Raunkier (E l l e n b e r g , M u e l l e r- D o m b o i s , 1967). pH soil analysis and electric conductivity (EC) were performed at all investigated localities. It was established that the community dom- inates 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 officina - le L. and Rumex obtusifolius L. are the most frequent. In relation to life forms, the community has hemicriptophytes character, and in relation to phytogeography Eu- roasian and Middle Europaean floral elements are dominant, with a high presence of cosmopolitan and adventive floral elements. On the locialities Veliko Ratno os - trvo (island) and Makis, EC values point to the fact that the amount of nutrient in the soil is higher than at other localities.

Impact of Invasive Aster lanceolatus Populations on Soil and Flora in Urban Sites

ABSTRACT Invasive plants are one of the major treat to local communities and ecosystems in urban habitats. Aster lanceolatus Willd. is one of the most spreading invasive plant species in Serbia and to examine its impact on soil, flora and aboveground biomass in urban habitats we investigated the pH, electrical conductivity and concentration of trace elements (Zn, Cu, Ni, Mn) in four invaded and four uninvaded plots in urban habitats. We also studied floristic composition and floristic richness regarding these invasive plant populations. These parameters were assessed along transects arranged in the cross shape, running from the centre of the invaded area towards the peripheral uninvaded area. Trace elements were analysed using atomic absorption spectrophotometer. Statistical differences were analysed using ANOVA and post-hoc LSD-tests. The results showed an important decrease of the number of species and herbaceous cover under A. lanceolatus populations. There were no statistically significant differences between invaded and uninvaded patches when soil pH and electrical conductivity were considered. The concentration of Zn, Mn and Ni in the soil was higher in invaded areas. The content of Zn in aboveground biomass collected from invaded compare to uninvaded areas was higher. This study raises the possibility that invasive species changes soil characteristics and create conditions for their spreading.

Micropropagation of Achillea millefolium L. on half-strength MS medium and direct rooting and acclimatization of microshoots in hydroponic culture.

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]

Effect of explant type on the rooting and acclimatization of Dianthus serotinus Waldst. & Kit.

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]

Effects of the time of cuttings collection and IBA concentration on the rooting of softwood cuttings from elite trees of Cornelian cherry (Cornus mas L.) in Belgrade area.

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: pracenje uticaja, adaptacija i ublažavanje]

Quick-dip and contact method of cutting rooting of Zelkova carpinifolia (Pall.) K. Koch as an alternative non-invasive species

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.

Public attitude in the City of Belgrade towards invasive alien plant species.

Biological invasions are seen as a major threat to biodiversity at a global level, while the number of new invasions is increasing at an alarming rate. Raising the awareness of the public, academic world and policy makers about the dangers caused by invasive species, is essential for the creation of the support needed to implement and coordinate the policies necessary to address this problem. The aim of this study is to determine the level of local public awareness of the existence of these plant species, examine the public attitude towards alien invasive plant species and willingness to get involved in the prevention of their spreading. The survey was conducted in four nurseries on the territory of the City of Belgrade and the investigation dealt only with alien invasive woody plant species. Thirty customers were questioned in each of the four nurseries. The results show that local public is uninformed on the issue of invasive plant species. It is necessary to constantly and intensively raise their awareness of this issue, as well as the awareness of harmful consequences that may occur due to the uncontrolled spreading of alien invasive species. This refers not only to the population that visits the nurseries and buys the plants there and to those employed in plant production and selling, but also to the whole local public and decision makers.

Spontaneous changes a basis for new ornamental woody plant cultivars

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. .

Improving germination of Chionanthus virginicus L. seed by using gibberellic acid (GAZ)

The aim of this experiment was to explore effects of gibberellic acid on Chionanthus virginicus L. seed germination. The species has great horticultural values but due to problem in propagation it is rarely used. The seed possesses double dormancy: egzo and endo dormancy. Gibberellin has shown helpful in overcoming endo dormancy which is confirmed with this species. Different concentrations of GA3 had different influence. The lower one has shown stimulative effects while the higher one has shown the inhibitor effects. It is also confirmed that endocarp prevents germination.