Vera Rakonjac

The study evaluated the effects of six rootstocks on the leaf mineral composition and nutritional balance of four apricot (Prunus armeniaca L.) cultivars. The rootstocks comprised five seedling rootstock treatments (‘Green Gage’, ‘Belošljiva’, ‘MY-KL-A’, ‘Iroquois’, and ‘Crvena Ranka’) and one clonal rootstock (‘Myrobalan 29C’), while the evaluated cultivars were ‘Buda’, ‘Ruža’, ‘NS-4’, and ‘Novosadska Rodna’. The experiment was conducted in 2022 and 2023. Twenty-nine elements were analyzed in leaves collected 120 days after full bloom, of which 21 were detected and quantified. Rootstock significantly affected the concentrations of most mineral elements. Trees grafted onto ‘Belošljiva’ had the highest leaf concentrations of Ca, Mg, Zn, and Mn, whereas those grafted onto ‘Myrobalan 29C’ had the highest concentrations of K, P, and Fe. ‘MY-KL-A’ generally resulted in the lowest concentrations of several essential elements and the greatest nutritional imbalance, expressed as the sum of the absolute deviation from optimum percentage indices (ΣDOP = 360.50). The lowest ΣDOP value was recorded for ‘Belošljiva’ (231.85). Among the cultivars, ‘NS-4’ showed the most balanced mineral status (ΣDOP = 268.99), whereas ‘Novosadska Rodna’ showed the greatest imbalance (ΣDOP = 321.85). The leaf concentrations of several elements were higher in 2023 than in 2022, possibly in association with the greater and more evenly distributed precipitation recorded during the 2023 growing season. Trace and potentially toxic elements, including Al, Ba, Sr, Pb, Ni, Cr, and Co, were also quantified in the analyzed leaf samples. Overall, leaf mineral composition and nutritional balance were influenced by rootstock, cultivar, and year, with ‘Belošljiva’ providing the most favorable nutritional balance under the conditions of this study.

The aim of this study was to determine the influence of genotype, environmental factors across three consecutive years (2022-2024), and incubation temperature (17°C and 20°C) on in vitro pollen germination and pollen tube length in sour cherry, as well as to monitor flowering phenology during the same period. Six cherry genotypes were used: two cultivars created in the Republic of Serbia (“Sofija” and “Sumadinka”), one introduced cultivar (“Érdi Bötermö”), one autochthonous cultivar (“Feketicka”) and two promising genotypes (“GV-6” and “GV-10”). The flowering phenophase was recorded as the beginning, full and end of flowering. To determine germination and pollen tube length, pollen was collected and sown in Petri dishes on an agarose-sucrose nutrient medium and incubated at the two temperatures for 24 h. The obtained results demonstrated that flowering time varied between years in terms of date and duration. In vitro pollen germination ranged from 3.16% to 53.75%, while pollen tube length ranged from 225.6 μm to 960.2 μm. Significant differences were recorded between most sour cherry genotypes for both pollen germination and tube length. Differences between years were also significant, while incubation temperatures did not significantly affect the evaluated traits. The significant influence of many interactions, as established by analysis of variance, indicates that the response of genotypes to environmental conditions was different, which could be explained by differences in their stability. Knowledge of pollen germination and pollen tube growth plays a crucial role in understanding the value of a cultivar as a pollinator, both for commercial cultivation and breeding.

The efficacy of sweet cherry production is highly dependent on the regularity of flowering events and genetic-determined relations between female sporophyte and male gametophyte, which became even more important with higher flowering temperatures caused by climate change. Special attention is paid to the genetic diversity that provides essential sources of potential temperature-tolerance genes. Our study aimed at the genetic and reproductive characterization of Balkan cherry cultivars of autochthonous origin (‘Canetova’, ‘G-2’, ‘Dolga Šiška’ and ‘Ohridska Crna’), and six potential pollenizers. To identify S-haplotypes, the polymerase chain reaction (PCR) method was used to detect the S-ribonuclease (S-RNase) and S-haplotype-specific F-box protein (SFB) alleles, combined with fragment analysis and S-RNase sequencing. Pollination experiments were performed at three Balkan localities over two flowering seasons, and the fluorescence microscopy method was used to assess the cultivars’ male/female reproductive behaviour. A novel S-RNase allele S₄₀ was identified in ‘Ohridska Crna’ for the first time. ‘Ohridska Crna’ also demonstrated the best adaptability to higher temperatures regarding primary ovule longevity. This feature makes it desirable from the aspect of breeding new cultivars that can withstand the impacts of climate change. The findings on male-female relations and their temperature dependence open up the possibility for yield prediction and smart horticultural decisions that can be made to guide cherry production.

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The phenotypic variability of 50 European plum ( Prunus domestica L.) cultivars from the germplasm collection of the Faculty of Agriculture in Belgrade was evaluated on the basis of 7 qualitative and 24 quantitative traits over three years. A great diversity between cultivars was found for all analysed traits. The results show that qualitative traits play an important role in the identification of cultivars, as each cultivar has a unique combination of scores. Among the quantitative traits, the greatest variation was found in yield efficiency (0.027–0.757 kg cm ⁻² ; CV = 67.0%), yield (4.4–35.7 kg tree ⁻¹ ; CV = 45.6%), maturity index (9.4–42.9; CV = 36.1%), titratable acidity (5.2–17.2 g l ⁻¹ ; CV = 29.4%) and fruit weight (16.5–73.7 g; CV = 29.6%). Principal component analysis (PCA) revealed that the traits related to ripening time, fruit weight, quality and yield accounted for most of the observed variability. Cluster analysis (CA) grouped the analysed cultivars into two main clusters with several subclusters. The results of the present work provide important information on how to best utilise these plum cultivars and can help breeders to select the most diverse cultivars with the best fruit and yield characteristics to be crossed in future breeding programmes.

The aim of this study was to examine the dimensions and surface morphology of pollen grains of some sweet and sour cherry genotypes through scanning electron microscopy (SEM) as an additional alternative identification tool. In vitro pollen germination and pollen tube length as indicators of their viability were determined as well. Observations were carried on 10 sweet cherry (Prunus avium L.) and 7 sour cherry (Prunus cerasus L.) genotypes. All genotypes had prolate, tricolpate pollen grains, and striate exine ornamentation, with more parallel longitudinal ridges. Significant differences among genotypes within species and between species were found for most pollen grain characteristics and exine ornamentation. In both sweet and sour cherry the largest variability was recorded for colpus length (CV = 15.0% and 12.9%, respectively). For sweet cherry genotypes, in vitro pollen germination and pollen tube length ranged between 1.4% to 51.5% and 360.4 to 669.3 μm respectively, while for sour cherries they ranged from 15.5% to 37.0% and 96.3 to 960.2 μm, respectively. The results of the correlation analysis showed that in vitro pollen germination correlated positively with pollen length/pollen width (L/W) ratio (r = .640) and furrow width (r = .588), and negatively with the number of ridges (r = −.517), while pollen tube length was not significantly correlated with any of the studied characteristics. Principal component analysis (PCA) revealed that pollen length, pollen width, L/W ratio, colpus length, mesocolpium width, and ridge width are relevant tools to discriminate among the studied genotypes. The measurements made on pollen grains did not reveal individually big differences, but when all features were considered together, the pollen of each genotype exhibited a unique pattern. The distribution on the scatter plot showed considerable variation among sweet and sour cherry genotypes based on pollen morphological characteristics, which led to their distribution into two separate groups. This demonstrates the ability to distinguish cherry species based on pollen morphological characteristics determined by SEM. To improve discriminative ability for genotypes within species combination between pollen ultrastructural analysis, morphological and molecular markers is desirable, in subsequent work.Research Highlights: Significant differences in pollen characteristics between sweet and sour cherry. Significance of pollen morphology in taxonomic differentiation. Significance of SEM studies for the taxonomic identification.

This paper presents the results on the study of promising vine hybrids in the Nis wine-growing region. The following promising vine hybrids were obtained from three different crossing combinations: NI 11-92 (Prokupac x Gamay Noir), NI 8-92 (Smederevka x Traminer Savagnin rose), and NI 2-92 (Smederevka x Riesling Rhine). The hybrids were created in the “Centre for Viticulture and Winemaking” in Niš. The tested hybrids differed in their cropping potential, grape yield and quality, chemical composition and sensory evaluation of the wine.