Title: BIOLOGICAL AND PRODUCTIVE CHARACTERISTICS OF EARLY SWEET CHERRY CULTIVARS IN THE BELGRADE DANUBE REGION

Authors: Dragan Milatović, Gordan Zec, Đorđe Boškov, Dejan Đurović, Boban Đorđević

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Abstract: In the period of five years (2017-2021) in the area of Belgrade, the phenological characteristics, vigour, yield and fruit quality of nine sweet cherry cultivars of early ripening time were examined. The ‘Bigarreau Burlat’ cultivar was used as a control for comparison. The average flowering time was in the first half of April, and the ripening of fruits was in the second half of May. The cultivars ‘Kossara’ and ‘Rozita’ (1.2 kg) had the lowest average yield per tree, and the yield was highest in the cultivar ‘Merchant’ (4.1 kg). In three of the five years of research, late spring frosts occured, which significantly reduced the yield. Three cultivars (‘Merchant’, ‘Chelan’ and ‘Early Lory’) obtained a significantly higher yield compared to the control, while two cultivars (‘Early Lory’ and ‘Chelan’) had a significantly smaller trunk cross-sectional area. The average fruit weight varied from 6.4 g (‘Djuti’) to 8.8 g (‘Sweet Early’). The content of soluble solids was the lowest (13.5%) in the cultivar ‘Rita’, and the highest (16.2%) in the cultivars ‘Merchant’ and ‘Chelan’. The best sensory scores for the fruit quality were given to the ‘Sweet Early’ cultivar, which is the most promising for growing in the Belgrade Danube region.

Key words: Prunus avium, flowering, ripening, yield, fruit characteristics

Title: MORPHO-HISTOLOGICAL CHARACTERIZATION OF GRAFT UNION OF SWEET CHERRY TREES

Authors: Mirjana Ljubojević, Tijana NarandŽić, Vladislav Ognjanov

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Abstract: Adequate selection of rootstock/cultivar combination prevents potential future difficulties in growth and development of grafted trees, which could severely jeopardize fruit production. Discrepancies between data obtained from previous anatomical investigations of leading cherry rootstocks and selections and practical observations regarding tree growth altering, imposed the need for further investigation of potential mechanical barriers to water transport through the plant-rootstock, graft union and scion, or other imbalances between graft constituents. Thus, this study aimed to determine possible incompatibility between rootstocks and scions belonging to genus Prunus, sub-genus Cerasus. Initial histological characterization was conducted on sweet cherry ‘Summit’ grafted on three rootstocks of different vigor Prunus cerasus L. ecovar. ‘Oblačinska’, Prunus avium  Prunus pseudocerasus ‘Colt’ and Prunus mahaleb L. ‘Mahaleb’. In order to investigate different rootstock/scion interactions, cultivars ‘Bigarreau Burlat’, ‘Summit’ and ‘Hedelfingen’ were grafted on four standard rootstocks Prunus avium L. ‘Mazzard, ‘Mahaleb’, ‘Colt’ and Prunus cerasus  Prunus canescens ‘Gisela 5’, and one selection of Oblačinska sour cherry. Diameters and cross-section areas of rootstock, graft union and scion were measured, as well as secondary cortex areas of all investigated graft constituents. Concerning graft union formation, longitudinal cross-sections of one-year-old trees showed very good compatibility of ‘Summit’ cultivar with Oblačinska sour cherry and ‘Mahaleb’. When grafted on ‘Colt’, vascular tissue joining was weaker and greater necrosis of both pith and conductive tissues was observed. Bud grafted trees had higher diameters of rootstock, graft union and scion than those scion grafted, and the following descending values order was found: graft union > rootstock > scion. In scion grafted trees, the trend was different: graft union > scion > rootstock, while the difference in rootstock and scion diameters in the first year after grafting was within range of 0.7-2.6 mm. Maximal values of diameters with both grafting methods used, were found in ‘Summit’/‘Colt’ combination. Graft constituents’ investigation of three-year-old trees showed similar thickening of ‘Colt’ and grafted cultivars, in combination with ‘Mahaleb’ and ‘Mazzard’, rootstock thickening was stronger, while low vigorous rootstocks ‘Gisela 5’ and ‘Oblačinska’ sour cherry showed slower thickening rate than cultivars. Both rootstock and scion cross-section areas were lowest in trees grafted on ‘Gisela 5’ and ‘Colt’, followed with ‘Oblačinska’ sour cherry, while highest values were observed in combination with ‘Mahaleb’ and ‘Mazzard’ (values within range of 494.6-2,514.8 mm2 for rootstock, 585.1-1,801.1 mm2 for scion). In all rootstock/cultivar combinations, secondary cortex area was greater on graft union crosssection compared to rootstock. Also, in trees grafted on ‘Gisela 5’ and ‘Oblačinska’ sour cherry scion secondary cortex areas were 19% and 26% larger than in rootstocks. Results indicated that excess callus tissue surrounding the graft union do not represent an exclusive barrier to the ascending and descending water flow in trees grafted on high vigorous rootstocks but that detemined differences in tissue thickening and phloem tissue formation during the years induce poor nutrition, development and root anchorage when grafted on low vigorous cherry rootstocks.

Key words: compatibility, cultivar, graft union, hydraulic conductivity, Oblačinska sour cherry, Prunus, rootstock, secondary cortex

Title: Effect of 6-benzyladenine and gibberellic acid application on productivity and fruit quality of plum cultivar ‘Čačanska Rodna’

Authors: Gordana Barać, Zoran Keserović, Jasna Mastilović, Žarko Kevrešan, Biserka Milić, Nenad Magazin, Maja Milović, Jelena KalajdŽić, Aleksandra Bajić

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Abstract: Plum production in Serbia is mainly extensive, followed by low and unstable yields per unit of area and small fruits with poor quality. In order to improve production and increase fruit quality, the influence of 6-benzyladenine (BA) and gibberellic acid (GA3) on fruit yield, size and storability was examined. The experiment was carried out 2016-2017 on cultivar ‘Čačanska Rodna’ grafted on the generative rootstock Prunus cerasifera Ehrh. with the Prunus spinosa L. as an interstock and vegetative rootstock ‘Wavit’. When the fruit diameter reached 10 mm in average, the following treatments were applied: 50 mg l-1 BA, 100 mg l-1 BA, 200 mg l-1 GA3 and the untreated control. Fruits were analysed at harvest, after cold-storage at 1 ± 1°C for 28 days (2016) and 20 days (2017) and after three days of shelf-life Š28 + 3 (2016) and 20 + 3 (2017)Ć. BA treatments significantly increase yield and fruit size, while the effect of GA3 was inconsistent. The highest yield and number of fruits per tree were achieved with the 50 mg l-1 BA in both rootstocks. Yield was increased by 118% at the ‘Wavit’ rootstock and by 66% at Prunus cerasifera/Prunus spinosa rootstock, compared to the control. The exception was 2017 for the ‘Wavit’ rootstock when the highest yield was achieved in plum trees treated with 100 mg l-1 BA. The colour expressed through chromaticity (C* hroma) varied between years, rootstock and treatments. During fruit storage, the value of bioyield point decreased significantly. In 2016 storage of plum fruits reduced bioyeld point for almost 50%, while in 2017 reduction was around 30%.

Key words: Prunus domestica L., ‘Wavit’, Prunus spinosa, bioregulators, storage, shelf life

Title: FOLIAR APPLICATION OF CALCIUM AND POTASSIUM IN THE FUNCTION OF STRAWBERRY FRUIT QUALITY

Authors: Marko Kesić, Nenad Magazin, Gordana Barać, Maja Milović, Jelena KalajdŽić, Biserka Milić

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Abstract: The experiment was performedin strawberry plantation with the aim of examining the effect of foliar application of calcium and potassium on fruit quality, i.e. the fruit size and chemical fruit properties. In addition, the aim was to determine how the treatments affected the ability to store fruits. The experiment analyzed the influence of: 1) calcium carbonate (0.5%); 2) calcium nitrate (0.5%); 3) WAKE-up® Liquid fertilizers (1%); 4) potassium nitrate (0.5%); 5) calcium carbonate (0.5%) + WAKE-up® Liquid (1%); 6) calcium carbonate (0.5%) + potassium nitrate (0.5%); 7) calcium nitrate (0.5%) + WAKE -up® Liquid (1%); 8) calcium nitrate (0.5%) + potassium nitrate (0.5%). The investigation also included control treatment with a standard fertilization program. The treatments were effective in preserving the quality of the fruit after cold storage and increasing the calcium content in the leaf. Also, the application of WAKE-up® Liquid showed an effect on increasing the weight, height and diameter of the fruit, and in combination with calcium nitrate had affect on fruit firmness after harvest. The treatments had impact on the contents of soluble solids and total acids, while had no affect firmness of the fruit after cold storage.

Key words: strawberry, potassium nitrate, calcium nitrate, FoliaStim, Wake up, fruit properties

Title: EFFECT OF HYDROPONIC GROWING OF MOTHER PLANTS AND CONTAINER POSITION ON PRODUCTIVITY AND QUALITY OF DAUGHTER PLANTS OF STRAWBERRY CULTIVAR ‘SENGA SENGANA’

Authors: Jasminka Milivojević, Dragan Radivojević, Mladen Radojičić

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Abstract: The objective of this study was to investigate the effect of container position with strawberry mother plants on daughter plants productivity and quality of produced tray plants. Study was conducted in the mother planting established in a high tunnel in Guča, during the period of 2018-2019. Certified frigo plants of the cultivar ‘Senga Sengana’ were planted in 3 l pots in May, 2018. In the first treatment, the pots were placed in gutters installed on tables, whereas in the second treatment, pots with mother plants were placed on the floor of the high tunnel. The applied density was 10 plants per square meter. Another part of the investigation was performed on daughter plants that were separated from runners of mother plants in the autumn of 2018 and stored in a chamber at -2°C during the winter, and then as frigo plants were planted in containers during the spring of 2019. Leaf rosette height and number of leaves per rosette were significantly higher in mother plants placed on the tables, while runner length and total number of daughter plants per mother plant were higher in plants placed on the floor. Effect of container position with mother plants on the quality of tray plants was not statistically significant in 2018. From the total number of frigo plants stored in a chamber at -2°C during the winter and planted in containers during the spring of 2019, 70% was rooted after planting. In the rest tray plants, an increased in number of leaves per rosette (11.33) and crown diameter (11.05 mm) were registered in this study.

Key words: containers, mother plants, vegetative development, daughter plant productivity, tray plants

Title: Monitoring of stone fruit viruses in Serbia

Authors: Darko Jevremović, Bojana Vasilijević

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Abstract: The results of the survey on the presence of seven viruses (cherry necrotic rusty mottle virus, cherry leaf roll virus, cherry rasp leaf virus, tomato black ring virus, tomato ringspot virus, prunus necrotic ringspot virus and apple mosaic virus) infecting stone fruits are presented in this paper. A total number of 107 samples from mother blocks and nurseries in 30 locations were collected and analyzed. Samples were analyzed with ELISA and RT-PCR methods. Cherry necrotic rusty mottle virus was detected in six samples (one sweet and one sour cherry, two plums and two apricots). No other viruses were detected in analyzed samples.

Key words: Prunus sp., viruses, ELISA, RT-PCR

Title: Preliminary results of ‘Timočanka’ plum cultivar storability

Authors: Aleksandra Korićanac, Ivana S. Glišić, Branko Popović, Olga Mitrović, Nebojša Milošević, Ivan P. Glišić

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Abstract: ‘Timočanka’ is a dessert plum cultivar created in Fruit Research Institute, Čačak. Although it has excellent fruit’s physical attributes, its storage potential has not been investigated so far. Commercial quality demands of plum cultivars aimed for fresh consumption mainly refer to physical properties, but nowadays an increased trend in society is healthy consumerism, particularly referring to bioactive compounds. For this reason, the presented study included evaluation of, not only physical properties of plum fruit, but also determination of total phenolic content and antioxidant capacity. No significant changes of fruit weight and soluble solids content after 21 days of cold storage were observed. Fruit firmness’ values were high on both analysis dates, notwithstanding fruit softening occurred during storage. Although ‘Timočanka’ is characterized by relatively low content of total phenols, the values of antioxidant capacity indicate that its consumption can increase the daily antioxidants intake.

Key words: Prunus domestica L., storage potential, fruit quality, physical properties, total phenolic content, antioxidant capacity