Dejan Zejak

Mr. Dejan Zejak

University of Belgrade, Belgrade, Beograd, Serbia

Research Focus & Metrics

Academic Career Length

6Years (2021-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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20 August 2021 in Agronomy
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Journal Article
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DZDejan Zejak
Dejan Zejak
IGIvan Glišić
Ivan Glišić
Velibor SpalevicVelibor Spalevic
Velibor Spalevic
PMPavle Mašković
Pavle Mašković
BDBranislav Dudic
Branislav Dudic
The physical-geographical features of the mountainous area of Montenegro cause difficulties in farmers’ life and work. The organization of the agricultural production faces a number of problems that limit the overall development of rural areas. Some agricultural crops, such as raspberry, have found optimal growth conditions and produce appropriate yields associated with good fruit quality in such mountainous area. The Willamette variety dominates the production and has broadly expanded, as some new varieties, most notably, Tulameen, Fertȍdi Zamatos, and Glen Ample. The aim of this paper was to examine the biological and production characteristics of two raspberry varieties—one floricane (Tulameen) and one primocane (Polka)—grown in two localities. We confirmed the general rule that at lower altitudes, these varieties (570 m a.s.l, Bijelo Polje) are characterized by earlier vegetation, flowering, and fruit ripening in comparison to plants at higher altitude (1040 m a.s.l, Mojkovac). The Tulameen variety started flowering on 15 May in Bijelo Polje (the flowering phenophase lasted for 29 days, until 12 June) and on 25 May in Mojkovac (the flowering phenophase lasted for 27 days, until 20 June). That is a delay of 11 days in relation to different locations. The Polka variety started flowering on 25 June in Bijelo Polje (57 days, until 20 August) and on 1 July in Mojkovac (flowering for 67 days, until 5 September). That is a delay of 7 days. The Tulameen variety started maturation on 14 June in Bijelo Polje (maturation lasted for 27 days, until 10 July) and on 22 June in Mojkovac (26 days, until 17 July), with a delay of 9 days. The Polka variety started maturation on 23 July in Bijelo Polje (the maturation phenophase lasted for 55 days, until 15 September) and on 5 August in Mojkovac (52 days, until 25 September), with a delay of 14 days. The results showed that the Polka variety had significantly higher total phenol content than the Tulameen variety (4.43 and 4.03 mg, respectively). In terms of locality, the Mojkovac raspberries had higher total phenol content than the Bijelo Polje raspberries. Polka raspberries also had a higher content of total flavonoids than Tulameen, whereas differences between localities in regard to the content of total flavonoids in the fruit were not significant. The content of condensed tannins and gallotannins in the raspberry fruit was similar in relation to both varieties and localities. Finally, the total antioxidant capacity was significantly higher in the Polka compared to the Tulameen variety, whereas the differences between localities were not statistically significant.

25 August 2022 in Notulae Botanicae Horti Agrobotanici Cluj-Napoca
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Journal Article
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DZDejan Zejak
Dejan Zejak
VPVera M. Popovic
Vera M. Popovic
Velibor SpalevicVelibor Spalevic
Velibor Spalevic
DPDragana Popović
Dragana Popović
VRVuk Radojević
Vuk Radojević
IGIvan Glišić
Ivan Glišić
Organic farming preserve and upgrade the biodiversity of the soil and biodiversity of the entire ecosystem by protecting the environment, plants, and human health. This study analyses organic plant production worldwide and in Montenegro (2000-2020) and discusses the prospects and challenges in developing organic plant production. Geographically, Montenegro has a diverse climate, suitable for the production of more types of fields crops, vegetables and fruits throughout the year. The paper compares the area of organic farms, the number of farmers, and share of organic in the overall agricultural land in the world and Montenegro, Europe, and several European countries similar to Montenegro in terms of relief or area (Switzerland, Slovenia, Slovakia, Estonia, Serbia, and Cyprus). Data were also analysed for a mountainous state, such as Switzerland, and a Mediterranean one, as Cyprus, as by its position and relief, Montenegro is at the same time a mountainous (northern) and a Mediterranean country (southern region). Shows are trends in plant production areas in Montenegro since it gained independence (2006) and comparison with the EU countries. Grassland production prevails in Montenegro with 85.89%, followed by fruit (12.26%) and cereals (1.62%). The total area under organic vegetable covered a small area compared to the production of fodder crops (3951.84 ha), fruit (563.98 ha), medicinal and aromatic plants (232.46 ha) and field crops (74.49 ha). Organic fruit production has the largest share in the northern part of Montenegro. Certified organic production brings benefits because health-safe products are a condition for preserving the environment and health.

26 June 2025
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Book Chapter
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DZDejan Zejak
Dejan Zejak
NANikola Abramovic
Nikola Abramovic
VSVelibor Spalević
Velibor Spalević

21 September 2023 in Notulae Botanicae Horti Agrobotanici Cluj-Napoca
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ZCZeliha Ciftci
Zeliha Ciftci
ESEbru Sakar
Ebru Sakar
Sezai ErcisliSezai Ercisli
Sezai Ercisli
Mehmet İlhan ODABAŞIOĞLUMehmet İlhan ODABAŞIOĞLU
Mehmet İlhan ODABAŞIOĞLU
DZDejan Zejak
Dejan Zejak
Velibor SpalevicVelibor Spalevic
Velibor Spalevic
Olive (Olea europaea L.) is one of the oldest cultivated fruit species in the world. Fruits and oils of autocthonous olive varieties (native Turkish olive varieties) with unique sensory properties (taste, smell and aroma) gain importance recently. Particularly olive oil companies looking for varieties that have distinct taste, smell and aroma in their oil. Propagation of olive varieties by cuttings and grafting is very difficult and expensive, therefore it is important to find solution for easy and mass propagation. Micropropagation is particularly beneficial to propagate plants that are difficult to reproduce conventionally or to ensure virus-free plants or plants with particular qualities. In this study, in vitro micropropagation success of two autocthonous olive varieties (‘Mavi’ and ‘Guleki’) grown in the origin center of olive, Southeast Anatolia, Türkiye was investigated. Both varieties, have distinct smell, taste and aroma and are difficult to root by cuttings. The effects of three different medium OM (Olive Medium), WPM (Woody Plant Medium) and DKW (Driver-Kuniyuki Walnut Medium) and two different growth regulators BAP (6-Benzylaminopurine) and Zeatin on shoot induction (proliferation) in the in vitro micropropagation of the olive varieties were examined. Obtained shoots were later subjected to in vitro rooting and acclimatization. The highest proliferation efficiency and shoot length for both varieties were obtained with the use of 1 mg Zeatin+0.1 mg GAɜ hormone combinations on OM medium. ‘Mavi’ variety formed more roots compared to ‘Guleki’ (3.33 vs. 2.75 per shoots), and gave the highest rooting rate of 74.33% with 2 mg IBA (Indole Butyric Acid) treatment on ½ OM medium. In terms of rooting rate, Guleki gave the highest rooting (100%) on medium containing ½ OM, 0.2 mg GA3 and 4 mg IBA. 60% and 75% of the micropropagated plants of ‘Mavi’ and ‘Guleki’ varieties adapted well to the external conditions.

19 June 2023 in Ekonomika poljoprivrede
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GRGordana Radović
Gordana Radović
DZDejan Zejak
Dejan Zejak
VPVladimir Pejanović
Vladimir Pejanović
Organic agricultural production requires higher financial investments than conventional agricultural production. Seed prices are higher, labor costs are higher, and there is the additional cost of certification. That is why the existence of incentive measures of agricultural policy is necessary for organic agriculture. The aim of the paper is to present the incentives paid from the agricultural budget for organic agriculture in Serbia and Montenegro. The authors conclude that subsidies for organic agriculture, although they are paid continuously and are a significant incentive, have a small percentage share in the agricultural budget in both countries. In Serbia, 1% and 3% of registered farms in Montenegro practice organic agriculture.

1 January 2025 in Journal of the Serbian Chemical Society
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Journal Article
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DZDejan Zejak
Dejan Zejak
BPBranko Popović
Branko Popović
ALAleksandar P. Leposavić
Aleksandar P. Leposavić
Velibor SpalevicVelibor Spalevic
Velibor Spalevic
VTVele Tešević
Vele Tešević
Volatile compounds of plum spirit have a decisive influence on its quality and are closely related to the method of production. In this paper, minor and major volatile of plum spirits produced in small artisanal distilleries of Montenegro, obtained by two batch distillation techniques traditionally used (single and double distillation in alembic of the same construction) were analysed by GC-FID and GC-FID?MS methods. All plum spirits contained all 8 major volatile compounds analysed by GC-FID method, but out of a total of 138 minor aromatic compounds detected, only 32 are common to all samples. Wide ranges of concentrations of most volatile compounds indicated the great heterogeneity of plum spirit production methods in Montenegro, included, among others, two different distillation techniques. ?h? princip?l c?mp?n?nt analysis have shown that differentiation of plum spirits obtained by single or double batch distillation is not possible using the all compounds analysed by GC-FID or GC-FID?MS, as well as compounds belonging the same chemical class, but rather based on the content of the volatile compounds typical for batch distillation tail fraction.