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Summary During May and June of 2021, a total of 123 grapevine leaf samples were collected and analyzed for infection by grapevine fanleaf virus (GFLV) and three viruses from the grapevine leafroll-associated virus complex -1, -2 and -3 (GRLaV-1, GRLaV-2 and GRLaV-3, respectively). The samples were collected from commercial vineyards, small backyard vineyards and grapevine nurseries located across the entire Vojvodina Province (Bačka, Banat and Srem). OEPP/EPPO sampling protocols were followed during the sampling of leaf tissues showing possible virus infection symptoms. Among the 123 samples, 47 were collected from Bačka region (Bačko Gradište − 11, Bečej − 10, Temerin − 15, Vrbas − 1, Hajdukovo − 10), 50 from Banat region (Srpska Crnja − 10, Vojvode Stepe − 10, Čoka − 10, Uljma −20) and 26 from Srem region (Šid − 6, Banoštor − 10, Sremski Karlovci − 10) and serological ELISA tests were performed for virus detection. GFLV was detected in five samples (4.06%), GLRaV-1 was detected in six samples (4.87%), while GLRaV-2 was not detected in any of the analyzed grapevine samples. GLRaV-3 was present in five samples (4.06%). When infection rates were examined in relation to cultivars, GFLV was detected in Cardinal, Zalagyöngye, Black Muscat, Italian Riesling and Dornfelder. GRLaV-1 was detected in cultivars Cardinal, Black Muscat, Italian Riesling and Merlot, and GRLaV-3 in cultivars Othello and Italian Riesling. Based on these results, it can be concluded that GFLV and GRLaV-1 and GRLaV-3 are present in vineyards across Vojvodina Province and affect different grapevine cultivars. To effectively control virus infections and their spreading, continuous monitoring of these viruses and their vectors is required along with the planting of healthy propagation material.

Chemical properties (L-ascorbic acid and total sugars content, pH, titratable acidity, and dry solid content), phenolic compounds (total phenolics, tannins, flavonoids, anthocyanins, and flavan-3-ols) and antioxidant capacity were measured in ripe fruits of wild-growing strawberry, bilberry, and elderberry from eastern Serbia. All three selected fruits are rich sources of nutraceuticals: vitamin C, sugars, and different classes of phenolic compounds and their extracts expressed high antioxidant activity. Elderberry fruits possess highest concentration of all measured biomolecules.

Severe climate alterations that seriously challenge fruit production, combined with the demand for healthy, pesticide-free fruits, continuously direct rootstock/cultivar selection towards high adaptable varieties breeding. This study aimed to investigate the rootstocks’ influence on the performance of grafted ‘Summit’ cherry trees, including potentially dwarfing Prunus cerasus, Prunus fruticosa and Prunus mahaleb rootstock candidates. Anatomical properties of rootstock and scion stems were investigated to determine variation among different rootstocks and scion-rootstock combinations and to establish the link between trunk hydraulic conductivity, effective tree crown volume and yielding potential. Cross-section anatomical characteristics varied significantly both in rootstock and scion stems, indicating a clear influence of rootstock genotype on grafted sweet cherry trees. It was observed that all investigated cherry rootstock candidates belong to the low-vigorous rootstocks, based on the estimated effective crown volume of grafted trees compared to ‘Gisela 5’, with values ranging from 0.86 to 2.97 m3 in the fifth year after planting. Results showed a statistically significant positive correlation between trunk hydraulic conductivity, effective tree crown volume and yielding potential, with correlation coefficients up to 0.96. Significantly higher effective crown volume and trunk hydraulic conductance of trees grafted on P. cerasus compared to the trees on control, as well as highest yielding potential, showed better adaptation of these rootstock candidates in the trial without irrigation implemented. It was found that PC_05_04 rootstock candidate could be considered as the most appropriate choice when raising the high-density sweet cherry plantations, due to assessed parameters of vegetative and generative growth.

The plum pox virus was discovered in Bulgaria between 1915 and 1918, hence the name "plum pox". Despite strict quarantine measures, as early as 1980s, this virus was widespread in whole Europe, but its presence was also confirmed in South and North America, Africa and Asia. The only continent where the infection with this virus has not been described yet is Australia. The presence of strains PPV-D, PPV-M and PPV-Rec has been confirmed in Serbia. The PPV-M strain spreads very quickly naturally, and it is considered as very dangerous for stone fruit trees. Trees infected with the plum pox virus do not decay, but bear fruit of poorer quality. Poorer quality of fruits reduces their market value, which leads to significant economic damage.

Plant viruses cause considerable economic losses and are a threat for sustainable agriculture. Due to the multiple possibilities of infection, they have become widespread. The use of healthy propagation material, free of viroids, viruses and bacteria, is an important strategy in disease control in viticulture. The early and accurate detection of plant viruses is an essential component of their control. Due to the widespread of Grapevine fanleaf virus (GFLV) and its devastating potential, various diagnostic methods are being used. GFLV detection methods based on the specificity of the protein cover (ELISA) and nucleic acid-based virus detection methods (RT-PCR, qRT-PCR). Symptoms of viral diseases are often not distinct and can be confused with those of abiotic stresses, so visual inspection is not reliable enough.

Market interest in terrestrial orchids has risen significantly in the last decade. Their therapeutic potential and growing consumption has brought some species close to extinction. This study aimed...

New protocols for successful asymbiotic seed germination of two European orchid species, Himantoglossum jankae Somlyay, Kreutz & Ovari and Spiranthes spiralis (L.) Chevall., were established in this study. The influence of two basal media, organic supplements, illumination, and cytokinins on germination, protocorm formation, and seedling development was examined. A strong species-specific dependence on illumination conditions and nutrient medium composition was observed. Improved germination under continual darkness indicated that H. jankae had negatively photoblastic seeds, while S. spiralis seeds could germinate under both light conditions examined in this study, but slightly faster development was achieved under the 16-h photoperiod protocol. The H. jankae seeds cultured on Knudson C medium failed to germinate in any medium combination, irrespective of the organic supplement use. The highest germination rate of H. jankae was achieved on Malmgren medium supplemented with coconut water, peptone, and L-glutamine, indicating that germination of this species was amino acid–dependent. Although S. spiralis seeds germinated on all medium combinations, Knudson C basal medium (without supplements) yielded better results when compared with the Malmgren medium. The best S. spiralis seedling development was achieved on the medium supplemented with 6-(γ,γ-dimethylallylamino) purine, while the cytokinin 6-benzyladenine promoted H. jankae seedling development. With the implementation of these protocols, well-developed seedlings were acclimatized to greenhouse conditions after 7 mo in culture.

Summary Sweet cherries (Prunus avium L.) contain various phenolic compounds which contribute to total antioxidant activity. The present study was conducted to assess the antioxidant activity of 15 sweet cherry cultivars from Vojvodina province (north Serbia). The free radical scavenging properties of fruits were evaluated employing two different methodologies, including DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging assay and ferric reducing antioxidant power (FRAP) assay. Strong correlations were found between total phenolics, tannins, flavonoids and anthocyanins and DPPH and FRAP assays. In particular, cultivar Peter showed the highest antioxidant capacity and possesses the highest amount of measured phenolic compounds. This investigation shows large variability among sweet cherry cultivars in measured chemical attributes.

Summary Ophrys sphegodes Mill. is a wild orchid species which is threatened and protected due to its pollination biology, small seed and habitat destruction. The aim of this study was to establish asymbiotic germination protocol for the purpose of ex situ conservation. Two basal media Knudson C (KC) and Malmgren (MM), supplemented with organic additives (peptone (PE), L-glutamin (A)e, folic acid, casein hydrolysate (CA)) added separately and control media KC--C and MM--C were used in the present research. All the nutrition media contained 2% sucrose, 7% agar and 1% activated carbon, while their pH was adjusted to 5.8 ± 0.02 before autoclaving at 121 ° C for 20 minutes. The seeds were examined under two illumination conditions, 0/24 light/dark (L/D) and 16/8 L/D. The presented results indicate a huge influence of illumination and nutrition media on the seed germination and protocorm formation. The seed germination was overall significantly more successful in dark conditions (0/24 L/D) than with lighting (16/8 L/D). Protocorm, rhizoids and shoot formation were achieved only on the seeds cultured on MM medium, while the KC medium caused only swelling of the embryo. Organic additives had positive influence on the germination rate. According to the obtained results, the best germination rate and seedling development were achieved on MM-PE media, cultured in dark. The presented procedure accelerates the germination period and can provide a large number of plants in a relatively short period of time so it can be used for conservation programs and mass production protocol.

Cherry breeding and genetic studies can benefit from genome-wide genetic marker assays. Currently, a 6K SNP array enables genome scans in cherry; however, only a third of these SNPs are informative, with low coverage in many genomic regions. Adding previously detected SNPs to this array could provide a cost-efficient upgrade with increased genomic coverage across the 670 cM/352.9 Mb cherry whole genome sequence. For sweet cherry, new SNPs were chosen following a focal point strategy, grouping six to eight SNPs within 10-kb windows with an average of 0.6 cM (627 kb) between focal points. Additional SNPs were chosen to represent important regions. Sweet cherry, the fruticosa subgenome of sour cherry, and cherry organellar genomes were targeted with 6942, 2020, and 38 new SNPs, respectively. The +9K add-on provided 2128, 1091, and 70 new reliable, polymorphic SNPs for sweet cherry and the avium and the fruticosa subgenomes of sour cherry, respectively. For sweet cherry, 1241 reliable polymorphic SNPs formed 237 informative focal points, with another 2504 SNPs in-between. The +9K SNPs increased genetic resolution and genome coverage of the original cherry SNP array and will help increase understanding of the genetic control of key traits and relationships among individuals in cherry.

Summary The food production at the global level is about to meet its border. Industrialization of agriculture correlates with an explosive enlargement of human population, during XX and at the beginning of XXI centuries. An ongoing process of environmental erosion has been speeding up during that period, not only in our physical surrounding, but also in biodiversity. A new direction in agricultural food production is in demand. Organic food production has been recognized as the way of providing safety and quality food, preserving the environment in the same time. In the other hand new land areas have to be explored for agricultural use, in order to enhance food quantity to meeting the increasing demand for food. These targets set new requirements in plant breeding. To fulfill these requirements the genetic variability harbored in genetic resources has to be preserved, examined and put to good use.

Genetic diversity and population structure of 6 in situ and 3 ex situ populations of European ground cherry (Prunus fruticosa Pall.) were investigated using 35 microsatelite markers. A total of 227 alleles were amplified with average of 6.49 per primer pair. The number of alleles varied from 91 to 182 in different populations. Observed heterozigosity (Ho) and expected heterozigosity (He) ranged from 0.850 to 0.910 and 0.531 to 0.715, respectively. Effective number of alleles (Ae) ranged from 1.833 to 10.488 per locus for all populations. Cluster analysis and principal coordinate analysis produced similar grouping patterns of all analyzed accessions. Population structure was best explained by K = 5. Population structure revealed that most of the accessions are highly assigned to a single cluster, while populations: Titelski, breg, Budapest, Kac and some accessions from populations Fruska Gora 1 and 2 could be considered as admixed. Moderate genetic differentiations between populations were observed based on Fst and Gst. High diversity level, observed within and between analyzed populations of P. fruticosa, indicates the importance of future in situ and ex situ conservation. Potential of P. fruticosa material for breeding of new cherry varieties and new rootstocks for sweet and sour cherry is discussed.

Main goal of this study was the establishment of unequivocal selection protocol in breeding size-controlling rootstocks with possible drought adaptability. Plant material, consisted of ‘oblacinska’ sour cherry (Prunus cerasus L. – OV) and ground cherry genotypes (Prunus fruticosa Pall. – SV), was propagated by softwood cuttings under controlled mist system. Analysis included detail anatomical investigation of fine and skeletal roots and rootstock stems. Each constituent contributed to the overall rootstock size-control capacity and potential drought adaptability. Fine roots contribution was estimated trough the active root surface area that significantly varied within and between investigated species, indicating different absorption capacities. Ratio between active—fine-roots surface area responsible for radial solution sinking and total root surface area, comprised of non-sinking skeletal roots and fine roots served as coefficient for reduced water uptake in theoretical hydraulic conductance calculations. Simultaneous examination of root system water capacity, axial conductance capacity corrected by radial sink capacity, and rootstock stem capacity, defined by anatomical characteristics, wood formation and thickening dynamics was established as reliable selection protocol for size–controlling capacity and hypothesized adaptability. Based on stated protocol greatest size-controlling effect is expect to be achieved within ground cherry genotypes – SV1, SV2, SV4, SV5 and SVKK, followed by ‘oblacinska’ cherry genotypes OV13, OV14, OV22, OV23, and OV24. Following the same approach, genotypes SV2–7 and OV14 are presumed to be the best adapted to drought and embolism caused by freezing/thawing and hydration/dehydration cycles.

In vitro embryo culture enabled satisfactory germination of immature seeds produced in crosses from early ripening sweet cherry varieties (Prunus avium L.). Three varieties —‘Rita’, ‘Bigarreau Burlat’ and ‘Carmen’— were crossed with ‘Early Star’ as male parent. Germination rate was affected by the developmental stage of both fruit and embryo. Fruit ripening stage was a critical factor for culture infection rate that increased with maturity. In-ovule embryo culture on Murashige and Skoog medium without hormones improved the embryo size but did not increase the germination rate due to a further increase in infection rate. Ex-ovule embryo culture on Murashige and Skoog medium supplemented with BA 1 mg L−1, NAA 0.5 mg L−1, 20 g L−1sucrose, 10 g L−1 sorbitol and 6 g L−1agar during the stratification time increased embryo length. Germination was performed on Brooks and Hough medium at the 22 ± 1 °C with 16/8 h light/dark photoperiod. The highest germination rate (75 %) was reached in embryos that were 3−4 mm in length, after 30-days stratification at 4 °C. Embryos in fruits at green-yellow stage that were 3−4 mm long were morpho-physiologically developed to produce bipolar seedlings, without combined application of embryo culture and micropropagation.

New challenges that food production is facing, requires novel approach in agricultural strategy. The scissors of growing demand for food and the limits of the Earth's resources are forcing plant breeders to run for the new borders, utilizing all the available genetic variation in order to create fruitful and economically sound cultivars. Aegilops sp. (Poaceae) is a potential source of genetic variation for wheat improvement. RAPD marker analysis was used in order to distinguish and evaluate different genotypes of Aegilops sp. population samples from the collection gathered during few years’ expeditions in South Adriatic, along the coastal, littoral and the inland parts of Montenegro. Ten randomly amplified polymorphic DNA markers (RAPDs) were tested: OPA-05, OPA-08, OPB-06, OPA-02, OPA-07, OPA-25, OPB-07, OPB-18, OPC-06, OPC-10 to examine genetic structuring on 18 samples of 6 populations of different Aegilops sp. According to global AMOVA, 75% of total gene diversity was attributable mostly to diversity within population (ΦPT =0.205 p=0.001), indicating that the groups of studied goat grass populations were seemingly to differing genetically. In contrast, 25% of the variation came from variation among populations. According to PCoA, the distribution of 18 goat grass accessions by Principal Coordinate Analysis shows 3 distinct groups. PCo axis 1, PCo axis 2, and PCo axis 3 account for 20.8%, 18.2% and 14.1% of the variation, respectively. The results showed that RAPD markers could be a convenient tool for investigating genetic variation and for detecting genetic structuring of populations. Genetic variability formed under natural selection was entrenched.

All the new challenges that food production has been experienced, requiresadequate response not only in wide agricultural practice, but also in modernbreeding programs. Broadening genetic variability is indispensable to meeting theborder set by climatic changes, land erosion, human population growth, andsustainable agriculture. Gathering genetic variability, forming and examininggenetic collection are integral part of the task. A germplasm collection of 220entries, consisting of cereal (Poaceae) genotypes has been formed. Geneticvariability of wheat (Triticum sp. ), barley (Hordeum sp. ), and goat grass (Aegilopssp. ), samples from the germplasm collection was analysed using gliadin blocks asprotein markers, as well as, Random Amplified Polymorphic DNA (RAPD)markers. Gliadin allelic variation was notable within Triticum sp. samples,revealing not only genetic divergence, but also the origin and the structure ofpopulations. Genotype variation and structure of populations of Hordeum sp. wasfollowed by hordein allelic variation. Sampled population expressed heterogeneityfrom two to five genotypes per population sample. Landraces, old and modernvarieties were separated in collection using hordein allelic variation, as well. Asmall, pilot, investigation was conducted on Aegilops sp. polymorphism usingRAPD primers. Number and percentage of polymorphic loci, effective number ofalleles, expected heterozygosity and Shannon’s information index were used toestimate genetic variation.

Twelve cultivars and selections of sweet and sour cherries were surveyed and characterized agromorphologically. A total of 33 characters, mainly defined by the International Plant Genetic Resources Institute and the International Union for the Protection of New Cultivars of Plants, were used to describe the tree, branches, leaves, blooming, and fruits. This allowed unequivocally clear separation between six distinct growth forms-compact, dwarf, upright (pillar), columnar, weeping, and standard form-as well as evaluation of their interaction with four rootstocks of different vigor. Natural tree habit diversity within distinct growth forms has the potential to reduce pruning and training requirements in cherry, particularly in medium- and high-density planting. The reported unique growth forms, within compact and columnar tree habit of sour and sweet cherries, combine specific genetic potential of scion fruiting habits and vigor. Genetic diversity was confirmed by simple sequence repeats. Research showed that multiple interactions exist between rootstock and genotypic determined components of the tree architecture, namely branching density, shoot growth dynamics, flower bud differentiation, and distribution. Developed ideotypes are new foundational concepts of modern production strategies bringing significant contribution to improvement of cherry orchard training systems, light interception, efficient fruit harvest, and economics.

The aim of this study was to predict the rootstock and scion cultivar vigor and rootstock/scion interaction on the basis of the knowledge of their morphological and anatomical characteristics and calculated theoretical hydraulic conductance. The simulated root system contribution to the plant vigor is numerical output of morphological parameter (number of skeletal roots), physiological parameter (active root surface area) and root and rootstock stem axial conductance quantified through theoretical hydraulic conductance. Theoretical hydraulic conductance at the graft union included ‘functional’ vessel area of hipobiont and epibiont. Rootstock stem and scion cross-sections were examined in three zones: inner (the oldest), middle, and outer (the youngest). Calculated functional vessel area and theoretical hydraulic conductance included all three zones of xylem in scion and two rootstock zones (middle and outer), since the inner zone of rootstock xylem surface area overlaps with the pith of the scion. Obtained theoretical hydraulic conductance of scions had values which are in accordance with the natural inherent tree vigor of the examined varieties. Graphical models were based on the interaction of the above parameters as a visual simulation of the pre-selection method. The lowest vigor was noted in all three examined varieties combined with rootstock ‘Gisela 5’, as well as the combination of European ground cherry and ‘Oblacinska’ sour cherry with variety ‘Summit’, whereas the most vigorous was ‘Colt’/‘Bigarreau Burlat’, which is in agreement with in vivo measured parameters on one-year-old fruit trees grown in the nursery.

SummaryThe search for growth-reducing rootstocks has produced selections of ‘Oblacinska’ sour cherry (Prunus cerasus L.) and European ground cherry (Prunus fruticosa Pall.). The methodological approach to germplasm collection was a compromise between a search for specific characters and random sampling of the population. On the principle of 19 variables in 27 accessions, this research brought valuable and diverse plant material into rootstock breeding. The vigour of adult trees on their own roots ranged from extremely weak, such as in selections of European ground cherry (SV1, SV3, SV4) and ‘Oblacinska’ sour cherry (OV31), to vigorous genotypes such as sour cherry (OV33 and OV34) and P. mahaleb. The natural habit of untrained trees varied from upright (e.g., SV7) to dropping (e.g., SV2). Internode lengths ranged from 1.36 cm (in SV8) to 4.11 cm (in SV4). Based on a PCA scatter-plot, six diverse sub-groups showing significant intra- and inter-species variability were distinguished. These findings were supp...

Biodiversity of natural populations, biodiversity located on farm and the introduced cultivars and selections are a rich source of genetic variability in sour and sweet cherries, but they have never been bread with the aim of creating decorative varieties. Low vigour ? dwarfing and upright ? sour cherry genotypes, NS 1/16 KK and NS 1/24 KK, were selected from natural population of Fruska Gora and private arboretum, respectively. Sweet cherry selections NS 6/15 K and RS 8/27 were part of on farm conservation of genetic resources. Furthermore, reduction in vigour was achieved by defining specific combining abilities as a result of rootstock/scion interaction. The outcome of this study is unique columnar and dwarf forms that integrate specific genetic potential of varieties and selections, their interaction with rootstocks and traditional horticultural skills. Collected biodiversity is another confirmation that the Balkan peninsula is one of the most valuable secondary centres of genetic diversity and inexhaustible gene pool for breeding both, varieties and vegetative rootstocks.

Several field collecting trips in the 2009-2011 period confirmed that forest fruit species are an inexhaustible genofond of extremely important varieties that yield fruit of excellent quality and high nutritive value, with wide range of applications, including nutritional, medicinal and food production. The aim of this work was to develop long term interactive and integrated strategy for selection of wild fruit species through different breeding methods, as well as popularization of selected products and their integration into intensive fruit growing. The most important morphological, ecological, and biological characteristics were studied and presented for Cornus mas, Sambucus nigra, Morus sp. and Rosa sp. For each studied fruit species, advanced selections for cultivar release has been reported.

Alfalfa is an autotetraploid, allogamous and heterozygous forage legume, whose varieties are synthetic populations. Due to the complex nature of the species, information about genetic diversity of germplasm used in any alfalfa breeding program is most beneficial. The genetic diversity of five alfalfa varieties, involved in progeny tests at Institute of Field and Vegetable Crops, was characterized based on RAPD markers. A total of 60 primers were screened, out of which 17 were selected for the analysis of genetic diversity. A total of 156 polymorphic bands were generated, with 10.6 bands per primer. Number and percentage of polymorphic loci, effective number of alleles, expected heterozygosity and Shannon's information index were used to estimate genetic variation. Variety Zuzana had the highest values for all tested parameters, exhibiting the highest level of variation, whereas variety RSI 20 exhibited the lowest. Analysis of molecular variance (AMOVA) showed that 88.39% of the total genetic variation was attributed to intra-varietal variance. The cluster analysis for individual samples and varieties revealed differences in their population structures: variety Zuzana showed a very high level of genetic variation, Banat and Ghareh were divided in subpopulations, while Pecy and RSI 20 were relatively uniform. Ways of exploiting the investigated germplasm in the breeding programs are suggested in this paper, depending on their population structure and diversity. The RAPD analysis shows potential to be applied in analysis of parental populations in semi-hybrid alfalfa breeding program in both, development of new homogenous germplasm, and identification of promising, complementary germplasm.

Prunus cerasus L. `Obla?inska? sour cherry germplasm was established in vitrodirectly from in situ plants on different explant collection dates, enabling quick clonal multiplication and introduction to a rootstock breeding program. Rosette initiation of four investigated genotypes was possible from November to April on the medium containing Schenk and Hildebrandt (SH) macroelements, Murashige and Skoog (MS) microelements, and vitamins supplemented with (in mg L?1) 6-benzyladenine (BA), 0.5; indole-3-butyric acid (IBA), 0.01; gibberellic acid (GA3), 0.1; citric acid, 10; and L-ascorbic acid, 10. The lowest percent of contamination was noted in November and December, when dormant buds were used as an explant source, and the highest percentage was found with actively growing shoot tips. The elongation phase of rosettes initiated from dormant buds remained a major obstacle. Survival rates of shoot tips obtained in April were high and subsequent growth more prominent. An increasing index of multiplication from 1.5 to 1.9 was noted on Driver and Kuniyuki walnut medium (DKW) with 0.8 mg L?1 BA and 0.01 mg L?1 IBA in the `OV 32? genotype. Rooting percentages of 71.3% and 81.3% were achieved in `OV 17? and `OV 32? genotypes, respectively, on half-strength MS medium with 1 mg L?1 IBA.

Genetic diversity of cherry species collected in Serbia has been investigated using 26 simple sequence repeat (SSR) markers developed in Prunus. This material consisted of 77 cherry accessions corresponding to the five following species, Prunus cerasus, Prunus avium, Prunus fruticosa, Prunus mahaleb, and Prunus serrulata. A total of 98 alleles were detected, with an average of 3.7 putative alleles per primer combination. Sixteen unique, species-specific, alleles were detected with nine primer pairs in four species, P. avium, P. cerasus, P. mahaleb, and P. serrulata. The highest number of unique alleles, 8, was observed in P. mahaleb and no species-specific alleles were detected in P. fruticosa. SSR markers generated unique fingerprints for all cherry accessions. Cluster analysis classified accessions into four groups according to their taxonomy, where P. avium and P. cerasus were grouped together, supporting P. avium as one of the progenitors of sour cherry. The highest genetic variability and potential value in rootstock breeding was observed in P. mahaleb and P. serrulata material. Principal component (PC) analysis explained more than 50 % of the total observed phenotypic variability using the first two components. The most important characteristics of PC1 were leaf length and width, fruit taste, color of leaf nectaries, fruit weight, leaf blade margin incisions, petiole length, size of vegetative buds, and length of internode. The most important characteristics of PC2 were shape of leaf blade at base, fruit skin color, and leaf blade length and tip angle. The investigated germplasm proved to be sufficiently genetically diverse for use in breeding programs and development of new cherry cultivars and rootstocks.

In order to investigate the effect of phytohormones exogenous auxins on the level of the mechanical injury induced oxidative stress, intensity of lipid peroxidation (LP) was measured in rootstocks of cherry softwood cuttings. Basal parts of the cuttings and leaves of five rootstocks (Mahaleb 1 and 2, Gisela 5, European ground cherry (EGC) and “Oblačinska” sour cherry) were sampled 0, 2, 4 and 6 days after cutting. Cuttings were treated with 0.5% solutions of three auxins: α-naphthylacetic acid (NAA), indolebutyric acid (IBA) and combination of these two (INCIT K). Results obtained for the LP intensity varied depending on the rootstock, plant organ and auxin applied. The best LP-lowering effect of auxins occurred in all genotypes when treated with NAA. In the leaves, the LP peaked on the 2nd day while the best LP-lowering effect was recorded in European ground cherry rootstocks on the 4th day, independently of auxin applied. The highest MDA production in leaves was recorded in Mahaleb 2 and European ground cherry rootstocks treated with IBA (60-90% higher then control) two days after the cuttings were made. It has been established that in the most of the rootstocks examined auxins showed lowering effect on LP which points to their positive effect, not only on rooting of softwood cuttings, but on their antioxidant protection system, as well.

The effect of exogenously applied auxins on mechanical injury induced oxidative stress was studied in 6 promising rootstock selections of Prunus cerasus L., P. mahaleb L., and P. fruticosa Pall. Investigated selections were included in low-vigorous rootstock breeding programme for sweet and sour cherries. The standard rootstock PHL-A was used as a control, due to successful rooting. Leaves of investigated rootstocks were collected on: 0, 1st, 3rd and 7th day of inserting softwood cuttings into the rooting substrate under a fogging system with 95-99% average relative humidity. Exogenously applied auxin mixture consisted of 0.8% α-naphthylacetic acid (NAA) and 0.5% indolebutyric acid (IBA). Mechanical injuries during rooting period represent one of the factors that induce stress in softwood cuttings. Intensity of LP is used as a valuable biomarker of plant response to various abiotic factors. Differences in intensity of LP between auxin-treated and -untreated cuttings were examined. Almost all of investigated selections had lower LP intensity after auxin application (11.4-47.2%) between 1st and 3rd day. However, the most prominent change was in leaves of PHL-A (49.2%). The best LP-lowering effect were recorded in leaves of P. fruticosa, SV4 selection (56.9%) on 7th day and in P. mahaleb, M4 selection, on 1st and 3rd day (5.9, 5.8%), in comparison to untreated softwood cuttings. As for OV21 selection, LP intensity significantly increased in both treated and untreated cuttings on the 1st, 3rd and 7th day, but auxin-treated cuttings showed lower LP values, except on 7th day, reaching 221.3 nmol MDA equivalents g-1 fresh weight. Intensity of LP during vegetative propagation of selected genotypes could be used as one of the biochemical parameters in further rootstock selection for sweet and sour cherries.

The general aim of this research was to determine whether the cherry root cambium possesses similar water-stress adaptation abilities as the scion. Specifically, this study aimed to determine whether there is a shift in root xylem structure due to precipitation fluctuations and temperature increase during the growing season in two cherry species. Oblačinska sour cherry and European ground cherry roots with secondary structure were anatomically surveyed in detail, and correlated with meteorological conditions occurring during the vegetation when the roots were formed. Under environmental signals, both investigated species altered their radial root growth imprinting stops and starts in a cambial activity that resulted in the occurrence of intra-annual false growth rings. Changing environmental conditions triggered the shifts of large and small vessels throughout the false growth rings, but their size seemed to be mainly genetically controlled. Taking into consideration all the above, genotypes with moderate vessel lumen area&mdash, lesser or around 1200 &mu, m2 in the inner zone, as well as no greater than 1500 &mu, m2 in the outer zone&mdash, are presumed to be both size-controlling and stable upon the drought events. Thus, further field trials will be focused on the SV2 European ground cherry genotype, and OV13, OV32, and OV34 Oblačinska sour cherry genotypes.