Dragica Vilotic

Nickel content in plants and soil in the area of the protected natural resource “Avala” - Belgrade

The purpose of this research is above all focused on the aim of determining the load of ecosystem or rather soil and plants with the heavy metal Ni and the level of accummulation in this area so that on the basis of the obtained results adequate protection measures could be timely taken. The research of nickel (Ni) content in the leaves of herbs and woody plants growing under urban conditions in comparison with the nickel concentrations in the plant leaves in the protected natural resource “Avala” (16 km away from Belgrade) indicates that the recorded values of nickel concentrations by locations are statistically significantly different and range from A to F on locations 1, 2 and 3 while on location 4 in urban conditions the values range from A to B in accordance with Duncan’s Test.

Accumulation of Mn and Pb in linden ( Tilia platyphyllos Scop.) bark and wood

As an indicator of environmental pollution, we collected tree rings and bark of linden (Tilia platyphyllos Scop.) from four sampling locations in Serbia. Mn and Pb were determined with a spectrochemical method that has an argon-stabilized U-shaped DC arc with aerosol supply as excitation source. Increased concentrations of Mn in linden tree rings and bark were found at the Debeli Lug location, where the Mn transfer factors were largest. The availability of Mn in soil and tree rings was greatly influenced by pH. Since 1950, Mn level decreased more noticeably on acidic soils. Higher concentrations of Pb were found in linden tree rings and bark at the locations Fruška Gora and Zemun. Proximity of the road to Novi Sad at both sites may be a possible reason for this. The Pb transfer factor was highest at Fruška Gora. The ratio of bioavailable elements in soil for Mn and Pb were also calculated. Close correlations between Mn and Pb concentrations in linden tree rings and the ratio of bioavailable elements in soil were seen at all four locations.

Leaf stomatal traits variation within and among black poplar native populations in Serbia

Populus nigra as a keystone riparian pioneer tree species is one of the rarest and most endangered species in Europe due to the loss of its natural habitats. Genetic diversity existence is a key factor in survival of one species, and stomata as genetically controlled trait could be used for differentiation studies. With the aim of proving stomatal phenotypic variation of the four native populations of Populus nigra located on the banks of three biggest river valleys (Dunabe, Tisa and Sava) in the region of Vojvodina in northern Serbia, we examined various leaf stomatal traits (stomatal length and width, pore length and width, stomatal density, shape coefficient and stomatal and pore area). We tested the differences of stomatal traits among populations, interindividual variability - differences among trees, the intraindividual variability, the differences between sun-exposed and shaded leaves, among leaves nested in exposition and the differences in adaxial and abaxial leaf surface. Based on mixed model ANOVA results, interpopulation variability, as statistically significant differences, observed only for stomatal pore length and shape, while all examined traits showed interindividual variability. On the intraindividual level the results showed differences for stomatal traits, except for stomatal width, stomatal shape coefficient and stomatal density regarding leaf exposure. For better understanding of how morphological and stomatal characteristics vary in black poplar populations, further studies should be necessary involving controlled environmental conditions with the aim of examining phenotypic plasticity to changing climate conditions.

Bald cypress (Taxodium distichum (L.) Rich.) in the protected area Veliko Ratno Ostrvo.

Bald cypress is an introduced plant species in the protected area “Veliko Ratno Ostrvo“. It is growing outside its natural range, and in the given conditions it is capable of natural regeneration. The aim of the research was to study the adaptation, production and reproduction potential of this species, as the base for the conservation and targeted utilisation of the available gene pool.

Semi-dwarfs in the subspontaneous progeny and the synthesis of red oak dwarf cultivars

The main data on the occurrence of semi-dwarfs in the subspontaneous progeny of American red oak were researched. The grafting of scions from semi-dwarf trees on the stock of related species shortens the juvenile stage, i.e. accelerates the flowering, induces the self-fertilization and potential crossing of related species. The specific undertaking requires to: (1) define the desired type of the dwarf cultivar, (2) develop the model, and (3) plan the genetic nature of the conceived cultivar. The development of cultivars relies on the conceived and long-term activity.

Variability of chromosome number and morphology and gymnosperm improvement

The causes of monotypic and polytypic variability of the gymnosperm chromosome complex were studied. The development of karyogram and idiograms of the species should be applied in the aim of upgrading the breeding method and technique. The study of the chromosome variability depends on the knowledge on gene function at the level of chromosome and at the level of genome, i.e. at the supra-chromosome level.