Deyan Petrov* and Yordan Ivanov

Department of Forest Management, University of Forestry, 10 Kliment Ohridski Blvd., 1797
Sofia, Bulgaria. E-mail: petrovdeyan96@gmail.com

The aim of this study is to determine the current volume increment of high-stemmed European beech (Fagus sylvatica L.) stands within the territory of Petrohan Training and Experimental Forest Range at elevations ranging from 1400 to 1600 m a.s.l. Permanent and temporary sample plots were established in pure, simple, relatively even-aged stands. Trees within the plots were measured using callipers, and several heights within each diameter class were taken to determine the standing volume. Increment cores from trees of varying diameter classes were taken using a Pressler increment borer to measure the current radial increment over the last ten years. The width of annual rings was measured using CooRecorder software. The current volume increment was estimated using two methods. The first method is based on the difference between the volume measured at the time of the study and the volume ten years ago, while the second method was based on growth tables. Comparison was made between the volume increment results obtained by the two methods. The results indicate that the increment values established in the present study considerably exceed (on average by 5–6 times) the increment levels derived from the growth tables at stand density 1.0. The highest increment rates (8.1 and 8.4 m3∙ha-1) were recorded in stands with a density above 1.0 (1.2–1.3). Equations derived using Gerhardt’s formula for calculating the current increment were developed, which may be applied in beech forests within the enterprise’s territory at the indicated altitudes.

Received: 21 July 2025 / Accepted: 28 November 2025 / Available online: 02 December 2025

Open Access: This work is distributed under the Creative Commons Attribution 4.0 License.

Iliyan Zhelyazkov

Department of Agriculture and Herbology, Agricultural University of Plovdiv, 12 Mendeleev Blvd., 4000 Plovdiv, Bulgaria. E-mail: zheliazkov@mail.bg

The study was conducted on areas where the conservation agricultural systems were applied (No-Till). A crop rotation system of winter oilseed rape and winter wheat has been maintained for the past five years. The present research was carried out over two growing seasons (2019/2020 and 2020/2021). The absence of rotation and differences in the herbicide application, as well as the presence of the same species in the years of the survey, can be considered as the first signs requiring the conduct of annual regular surveys according to the methodology. Such monitoring is essential for the detection of herbicide-resistant weed species. The weed flora monitoring was performed in three agricultural locations: the town of Brezovo and the villages of Streltsi and Varben. A total of 54 weed species were identified, belonging to 22 botanical families, with a ratio of 89:11 (monocarpic : polycarpic). They were assigned to eleven biological groups, comprising 43 annual (monocarpic) and 10 perennial (polycarpic) species. Among the annuals, 6 were monocotyledonous, 36 dicotyledonous, and 1 bulbous species. The family Poaceae was the most abundant in the surveyed areas, represented by 9 species distributed across four biological groups: annual species, from which: winter spring – Apera spica-venti (L.) P.Beauv.; overwintering – Bromus arvensis L.; late spring – Setaria viridis (L.) P.Beauv., Echinochloa crus-galli (L.) P.Beauv., Setaria glauca (L.) P.Beauv.; early spring – Avena fatua L., Lolium temulentum L.; and perennials (rhizomatous weeds) – Sorghum halepense (L.) Pers. and Cynodon dactylon (L.) Pers. The aim of this research was to characterise the weed flora in crop production areas under the crop rotation system of winter oilseed rape and winter wheat.

Received: 21 July 2025 / Accepted: 04 December 2025 / Available online: 10 December 2025

Open Access: This work is distributed under the Creative Commons Attribution 4.0 License.

Marieta Nesheva (1)*, Petko Minkov (2)†, Svetoslav Malchev (1), Vanya
Akova (1), Irina Staneva (1), Boryana Stefanova (2), and Leyda Todorova (1)

1. Agricultural Academy, Fruit Growing Institute, 12 Ostromila Str., 4004 Plovdiv, Bulgaria. E-mails: marieta.nesheva@abv.bg*, svetoslav.m@live.com, vannnia85@abv.bg, tsarewa@abv.bg, l.todorowa@abv.bg
2. Agricultural Academy, Research Institute of Mountain Stockbreeding and Agriculture, 281 Vasil
Levski Str., Troyan, Bulgaria. E-mail: stefanova_b@abv.bg  †Deceased. Contribution approved by the co-authors.

In Bulgaria, the apple (Malus × domestica Borkh.) has a long history of cultivation, and there is a wide diversity of genetic resources in the country. Wild relatives of this fruit species can be found in forests or other habitats. The local genetic resources are valuable due to their good adaptation to the climate and soil conditions of the natural habitat. In addition, they often have a number of valuable characteristics, such as resistance to diseases and pests, which should be conserved and used as donors for breeding programmes. The aim of the current study was to investigate the diversity of seedlings and local genotypes mapped during expedition studies in the Troyan region, Central Balkan Mountains of Bulgaria, in order to assess their characteristics and select the most valuable ones for future breeding purposes. For these purposes, the fruit size, flesh firmness, the total soluble solids content (°Brix), the skin and flesh colour were measured. All the characteristics studied were highly variable in the population. Fruit flesh colouration varied from white to pinkish. Regarding chemical analysis, very high sugar content was recorded in PM 11 (18.08 %), PM 12 (18.32 %), and PM 25 (17.44 %). All analysed samples had higher invert sugar content and lower sucrose content. Of all the studied genotypes, PM 17 and PM 104 had very low acidity. The studied local forms do not comply with modern market demands but are valuable for preserving biodiversity and for breeding purposes because of their good adaptation to the climatic conditions in the region.

Received: 26 June 2025 / Accepted: 13 December 2025 / Available online: 17 December 2025

Open Access: This work is distributed under the Creative Commons Attribution 4.0 License.