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Optimization of nursery procedures is important part of introduction of white poplar genotypes in common practice. In this case we examined reaction of three genotypes of white poplar (Populus alba L.) on term of cutting preparation and slope aspect by survival and growth of rooted cuttings in PE "Vojvodinašume" nursery "Ratno ostrvo", near Novi Sad. There were two treatments concerning term of cuttings' preparation: a) middle of March (cuttings were stored in cool chamber at 2±1°C) and b) the day before planting at the first half of April. Also, there were examined the effect of slope aspect of nursery area: a) East-northeast, and b) Westsouthwest facing slope. Gained results suggest better survival and growth of rooted cuttings made at the middle of March and better survival and growth on area oriented to the West-southwest. The gained effects were mostly consistent for all examined genotypes (better results on West-southwest aspect and after early term of preparation). These results suggest that the research on the influence of terms of cuttings' production and the slope aspect could be important issues in creation and optimization of nursery technology suitable to the specificities of white poplar clones

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 tested the influence of the low pH values of the nutrient medium for rooting on the growth and development of the shoots of five white poplar (Populus alba L.) genotypes. After 35 days of in vitro cultivation following characters were measured: height of shoot, the number of roots, length of the longest root, the percentage of survival and rooting. Three different pH values of the medium: 3.0, 4.0 and 5.5, buffered by sodium citrate buffer, and standard medium for rooting with pH 5.5 without the addition of citric acid (control), sterilized in microwave oven, were used. Generally, a statistically significant lower values in all studied morphological parameters have been recorded on the media with pH 3.0, compared to all the other tested media. The highest values of all investigated parameters were observed in clone L-80. The results indicate that the in vitro test culture might help to narrow the selection of white poplar genotypes that could be used on acid soils.

One of the main cause of relativly slow afforestration with white poplar are problems in rooting of its hardwood cuttings. One way of stimulation of white poplar cuttings' rooting is treatment with appropriate plant growth regulators, mainly those with auxin effect. In this work the results of the experimental application of powder formulations with indolbutiric acid (auxin) and cobalt chloride (ethylene action inhibitor) in nursery conditions are presented. Beside effect of examined powder formulations, the effect of differences between genotypes (Populus alba cl. Villafranca and cl. L-12) was examined, as well as, for genotype Villafranca, the effect of differences between three nurseries. Obtained results suggest the positive effect of implementation of cobalt chloride in formulations dedicated to the stimulation of white poplar cuttings' rooting, as well as on differences between genotypes in their reaction on examined formulations. After the treatment of cuttings of Villafranca with combined formulation with 100 μM CoCl2·6H2O and 0,6% indolbutiric acid, beside pozitive effect on cuttings surivival, the positive effect on the rooted cutting height was achieved as well, resulting in significantly higher partition of plants apropriate for planting than in control (50-100% higher, depending on nursery). Presented results suggest the significant potential in the implementation of cobalt chloride in white poplar nursery production.