Provenance trials, as the subject of continuous analyses, provide empirical information about the plasticity of tree species. Changing climate and environmental conditions likely favor genotypes with high levels of plasticity. Finding the suitable provenance for the reintroduction of pedunculate oak to habitats that are threatened and where this species no longer exists provides important information for the targeted use of the available gene pool. The dominant ecological factors in the development of pedunculate oak forests are groundwater level and changes in the hydrological regime of habitats. In this study, we established nursery and field provenance trials to test two pedunculate oak seed provenances from different hydrological conditions to investigate the influence of seedlings' provenance and field microhabitat on growth parameters and survival. In the nursery trial, the height and ground level diameter were measured. After three years in the pilot object, the height and diameter were analyzed again, as well as the survival. To determine the microhabitat influence planting area was divided in two ways: three repetitions and two planting blocks. In this study, significant differences in analyzed growth parameters between the chosen provenances were obtained at the end of the first vegetation period. In later ontogenetic phases influence of the provenance is missing. As the difference between provenances disappears, the influence of microhabitat occurs (significant differences between repetition or planting blocks). After the second year of development, no significant difference was observed between the two provenances of different hydrological regimes, but there are significant differences between the microhabitats in the afforested area (established pilot object).

The leaf area of plant leave scan be considered as an indicator of the plant growth conditions, and its variability is usually associated with adaptation and response to the changing environment. The aim of this study is to investigate the relation of the leaf area parameters on growth of the narrow-leaved ash 1+0 seedlings from the nursery trial and determining variability between the 18 half-sib lines. The seedlings were obtained from seeds collected from 18 maternal trees found in the area of the special nature reserve Upper Danube Region. Ten randomly selected 1+0 seedlings per half-sib line were selected for further study, and all leaves per seedling were collected, herbarized and scanned. The leaf area of each leaf (LACL) was measured using an open-source image processing program – ImageJ, and the total leaf area per seedling (TLA) was calculated. Also, the number of leaves per plant (NCL) as well as the number of leaflets within each imparipinnate compound leaf (NLCL) were counted. The results showed that differences between studied attributes were statistically significant among 18 selected half-sib lines (p < 0.05). The most variable parameter was the total leaf area per seedling (TLA; CV=68.98%), which is strongly correlated to the leaf area per each leaf (LACL; r=0.95) and the number of leaflets (NLCL; r=0.94). In this study, we confirmed that leaf parameters were highly correlated to the growth of one-year-old Fraxinus angustifolia seedlings.

Pedunculate oak (Quercus robur L.) is one of the most important deciduous tree species in the Serbian and European forests. Different negative factors limit natural regeneration of pedunculate oak forests, so producing of high quality seedlings becomes imperative to ensure successful forest restoration. This research was conducted with to aim to determine whether acorn size is related to seedlings quality. Acorns were collected from the natural pedunculate oak forest and divided into two groups by their size. Acorns were sown in the spring into plastic containers after five months cold storage. Size of acorns was in the standard species range, though germination was low (< 20 %). Germination was more then double in group of large acorns in comparison to group of smaller acorns (19.2 %, respectively 8.6 %). Height and root collar diameter of produced seedlings were lower than seedlings produced in seedbeds in commercial nurseries in Serbia, but it was in range of container produced seedlings in some similar researches. Height to root collar diameter ratio and shoot to root ratio were considered as satisfactory for containerized seedlings. There was not strong correlation between acorn size and seedlings quality attributes.

Aiming to produce forest reproductive material at the family level, we tested quality of twenty Fraxinus angustifolia Vahl half-sib lines in the nursery experiment. We measured height (HT) and root collar diameter (DIA) of one-year old seedlings, and we monitored germination rate and mortality during the first growing season. Seeds of 20 half-sib lines originating from Sombor area (north Serbia) were sown in seedbed on autumn 2016. The seed dormancy was not broken in all seeds equally, resulting with un-uniform germination over a two months period. All measured attributes shows a statistically significant differences, indicating a strong effect of genetic control. The highest average and DIA were measured in half-sib line 7 (22.62 cm; 5.79 mm, respectively). The lowest average DIA was measured in half-sib lines 18 (2.85 mm) and 19 (2.94 mm), which can be result of growing density effect (104 seedlings m-2 for line 18 and 126 seedlings m-2 for line 19, compared to 40 seedlings m-2 for line 7). The correlation between DIA and HT is strong and positive (R=0.90). Due to its morphological superiority, half-sib line 7 could be recommended for mass production of Fraxinus angustifolia seedlings at the family level. Keywords: Height; Root Collar Diameter; Seedlings Quality; Narrow leaved ash