Implications of captive breeding for the reintroduction of the Saker falcon (Falco cherrug) in Bulgaria

R. Petrov1,2*, Y. Andonova1, Y. Gancheva3, I. Klisurov1

1Green Balkans – Stara Zagora NGO, Stara planina str. 9, 6000 Stara Zagora, Bulgaria
2Department of General Livestock Breeding, Faculty of Veterinary Medicine, Trakia University, Student’s campus, 6000 Stara Zagora, Bulgaria
3School of Sciences, Faculty of Science and Engineering, University of Wolverhampton, Wulfruna St, WV1 1LY Wolverhampton, United Kingdom

(Manuscript received 20 June 2021; accepted for publication 5 August 2021)

Abstract. The Saker falcon (Falco cherrug) is a globally endangered species recovered in 2018 in Bulgaria. The only known active pair currently breeding in the wild in the country is made up of captive-bred and released birds, part of the first reintroduction programme for the species in Bulgaria and globally. As part of the project, sourced Saker falcons of known European origin are bred ex situ, the juveniles are parent-reared and released in the wild by means of the hacking method. The aim of this study was to evaluate the success and effectiveness of the captive breeding and rearing methods. The objective of the study was to investigate, compare and assess the results from fertilization, hatching, survival and hacking of captive bred Saker falcons registered over a 10-year period (2011-2021) at the Wildlife Rehabilitation and Breeding Centre (WRBC) Green Balkans, with a more detailed comparison of the breeding activities carried out in 2020 and 2021 (as the reintroduction programme was restarted in 2020). The results show more than threefold increase in output of laid eggs with the employment of the double clutching method in 2020 and 2021, and an overall 65% release rate of the hatched in the WRBC Saker falcons, for the investigated period.

Study on the effectiveness of chemical and biological agents to control tomato leaf miner (Tuta absoluta Meyrick, 1917)

R. Mineva1*, V. Yankova2, N. Valchev1

1Department of Plant Production, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria
2Maritsa Vegetable Crops Research Institute, 32 Brezovsko shose Str., 4003 Plovdiv, Bulgaria

(Manuscript received 1 June 2021; accepted for publication 30 July 2021)

Abstract. In growing four tomato varieties in greenhouses, the effect of a conventional and integrated scheme for control of tomato leaf miner (Tuta absoluta Meyrick, 1917) was studied. Six consecutive treatments were performed at ten-day intervals. The conventional scheme includes the following products: Confidor Energy OD 0.08%, Ampligo 150 ZC 400 ml/ha, Coragen 20 SC 200 ml/ha, Exalt 25 SC 2400 ml/ha, Voliam Targo 063 SC 800 ml/ha and Voliam Targo 063 SC 800 ml/ha. In the integrated scheme the following products for plant protection are used – Confidor Energy OD 0.08%, Sineis 480 SC 250 ml/ha, Sineis 480 SC 250 ml/ha, Voliam Targo 063 SC 800 ml/ha, Neem Azal T/S 0.3% and Neem Azal T/S 0.3%. The effectiveness of the plant protection products against the tomato leaf miner, the degree of pest attack of the different varieties and the tomato productivity were studied in this experiment. It was established that in the conventional and in the integrated treatment scheme, the highest efficiency was shown by the product Voliam Targo 063 SC, applied in a dose of 800 ml/ha on the seventh day after spraying. The percentage of damaged plants was the lowest in the variety Clarosa F1 (4.00%), with the application of the conventional plant protection scheme. The results were similar in the integrated scheme – 6.00%, while in the control the degree of infestation reached 18.00%. The percentage of damaged fruits in both treatment schemes was 6.00%, significantly lower than in the control (24.00%). The highest tomato productivity was observed with the application of the conventional plant protection scheme in Manusa F1 variety.

Design parameters of furrow forming and compacting roller of the combined seeder STS-80

G. Hristova1*, M. Dallev2, G. Tihanov1

1Department of Agricultural Engineering, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria
2Department of Agricultural machinery, Faculty of horticulture with viticulture, Agricultural University of Plovdiv, 12 Mendeleev Blvd., 4000 Plovdiv, Bulgaria

(Manuscript received 22 June 2021; accepted for publication 10 August 2021)

Abstract. A turf seed drill (STS-80) has been designed, in which the seeds from the sowing machines are sent to the soil through seed pipes. The size of the seeds is relatively small, therefore it is a requirement for them to be sown at a depth between 0.5 cm and 1.5 cm. The drill allows the following operations to be performed simultaneously: soil furrowing, seed sowing, and soil compaction with a compaction roller. The structure of the individual bodies that make up the aggregate is essential for the smooth running of the work process. Two rollers have been developed, which allow the providing of the necessary agro-technical requirements for sowing grass seeds. The role of the roller mounted in the front part of the drill is to make furrows in the soil at a depth of 1.5 cm, where the grass seeds fall. The roller, located in the rear of the unit, dulls the surface of the soil after the seeds enter it. This creates additional dynamic force, which increases the degree of soil compaction and the intensity of destruction of soil aggregates at a certain mass of the roller.

Estimation of the economic efficiency of Lacaune sheep farms, based on theoretical bio-economic models

S. Slavova*

Agricultural Institute, 6000 Stara Zagora, Bulgaria

(Manuscript received 24 November 2020; accepted for publication 26 April 2021)

Abstract. The aim of the present study was to develop theoretical bio-economic models of Lacaune sheep farms and establish their economic efficiency. Based on three main criteria, 15 options were considered and analyzed. Data were processed using the program EWSH2 as a part of ECOWEIGHT Package for calculating economic weights in livestock. Revenues from sales, variable costs, gross margin and profitability before and after subsidies and per ewe were calculated. It was found that raising sheep of the high productive Lacaune breed could generate profit and provide profitability for the studied models of farms, regardless of the level of selection, type of production system, flock size and even the amount of subsidies. Nucleus farms reported the largest gross margin, followed by the basic and commercial farms. Profitability without subsidies showed the highest values for the nucleus flocks of 1000 ewes – 24.24% when adopting semi-intensive production system and 23.14% for the intensive one. With the addition of subsidies, nucleus and basic farms of 1000 ewes were considered the most profitable with 40% and 37.37%, as for both options the semi-intensive conditions were preferable. A tendency for the values of the studied indicators to grow with the increase in the number of ewes in the flocks was observed, as only for the variable costs it was reversed. Due to the lack of studies on economic efficiency of Lacaune sheep farms in Bulgaria, an additional detailed research, based on real data, is advisable to be conducted.


Effect of irrigation rate on Sudan grass yield, grown as a second crop

R. Bazitov*

Agricultural Institute, 6000 Stara Zagora, Bulgaria

(Manuscript received 24 October 2020; accepted for publication 12 May 2021)

Abstract. The aim of the present study was to establish the effect of irrigation rate on the yield of Sudan grass variety Engje-1, grown as a second crop for silage on meadow-cinnamon soil for the region of Southern Bulgaria. For this purpose, an experiment with Sudan grass variety Endje-1 on the experimental field of the Agricultural Institute – Stara Zagora, after its predecessor barley, was conducted. The Sudan grass was harvested in the brooming stage. Five variants were explored: Variant 1 – without irrigation (control); Variant 2 – with optimal irrigation, 75-80% of field capacity (FC); Variant 3 – irrigation as Var.2 but with removal of the first watering; Variant 4 – irrigation as Var.2 but with removal of the second watering; Variant 5 – irrigation as Var.2, but with removal of the third watering. It was found that the efficiency of 1m3 of irrigation water was the highest at the optimum variant (Var.2), where 5.36 kg of dry mass (DM) were produced by 1 m3 of water. With the removal of the second irrigation (Var.4), the yield on the dry mass decreased by 6.4% compared to the optimal variant (Var.2), and with the removal of the first irrigation (Var.3) the losses on the dry mass reached, 12.3%, respectively. The highest values of this indicator were obtained by varying the second irigation (Vаr.4) – 7.53 kgDM/m3 water. The coefficient of efficiency of the irrigation rate, representing the ratio between the increase of the yield (in comparison with the version without irrigation – Vаr.1), and the size of the realized irrigation norm had the highest value in the version without second irrigation (Vаr.4) and the lowest values for the version without first irrigation (Vаr.3).

Simulated acid rain impact on growth, yield and leaf anatomy of Dioscorea rotundata (L.)

E.P. Edosa*, J.F. Bamidele

Department of Plant Biology and Biotechnology, Faculty of Life Science, University of Benin, P.M.B. 1154, Benin City, Edo State, Nigeria

(Manuscript received 23 September 2020; accepted for publication 26 March 2021)

Abstract. Acid rain causes damage to crops and also has adverse effect on the soil and the environment. These have led to the abandonment of farmlands in affected areas. Southern Nigeria which is known for yam cultivation is subjected to acid rain resulting from gas flaring activities, importation of fairly used vehicles, power generation and industrial activities. The growth, yield and leaf anatomy response of Dioscorea rotundata (L.) exposed to simulated acid rain (SAR) of pH 2.0, 3.0, 4.0 and 6.0 (control) was investigated. Acid rain exposure caused morphological changes in plants including chlorosis, necrosis, and leaf folding. Acidic precipitation inhibited vine length, leaf number, chlorophyll content index and leaf area at pH 2.0; while growth was encouraged at pH 6.0. 22% of leaf surface area of D. rotundata L, was injured after simulated acid rain treatment at pH 2.0 while necrosis was absent at the (control) pH 6.0. Harvest index of D. rotundata was not significantly different (p>0.05) between the pH treatment groups; however, was slightly higher at the (control) pH 6.0. Percentage dry matter partitioning of D. rotundata leaf and stem was not affected by the acid rain exposure; nevertheless, maximum percentage dry matter of tuber was obtained at pH 4.0 and pH 6.0. Transverse sections of D. rotundata leaves showed cuticle wax damage and rupture of epidermis at lower pH 2.0 and 3.0. Mesophyll degradation and cytoplasm depletion was also observed in the treated leaves. The plant leaves revealed dark tissues in necrotic areas which may be phenolic compounds secretion. However, it became clear that significant increases in the growth parameters considered occurred at pH 6.0 (control).

Assessment of morphological variations in wild populations of Nile tilapia from South West Nigeria

O.M. Popoola*, A. Ebiwonjumi

Department of Fisheries and Aquaculture, Federal University of Technology, Akure, Nigeria

(Manuscript received 31 October 2020; accepted for publication 20 February 2021)

Abstract. The pattern of morphological variations among Oreochromis niloticus (Linnaeus, 1758) (Cichlidae; Teleostei) from three populations from South West Nigeria (Asejire reservoir, Ureje reservoir and Ogbese River were examined (n=10 speciments from each water body) with a view to investigate the genetic diversity using morphometrics and meristics indices. In general, 77.22% of the total variation in the sampled populations is from first principal component (PC1) and the characters that contributed to this variation are with pre-dorsal length, pre-pectoral length, pre-anal length, dorsal spine length and anal spine length. Canonical variate analysis (CVA) showed that O. niloticus populations from the three water bodies formed a separate cluster from each other and that there was an intersection between the Asejire and Ureje reservoirs samples and the Asejire reservoir with Ogbese River samples. However, the samples from Ureje reservoir and Ogbese River had no intersection. Cluster analysis revealed two major clusters with Ureje reservoir samples belong to one and Ogbese River and Asejire reservoir fall in the other cluster. Principal Components for meristic (PC1 and PC2) accounted for 46.49% and 24.17% revealed that transverse scales and scales surrounding the caudal peduncle, pre-dorsal scales accounted for the variation. The CVA revealed that of all the populations sampled, samples from Ureje reservoir are more diverse that the other two populations. The research disclosed that there is variation in O. niloticus populations from the three water bodies, which could be a result of genetic structure and environmental conditions, being major factors affecting morphological variability among different geographical populations. Further study on genetic differentiation of individuals from different species is necessary to confirm findings of the present study.

Physiological responses of Vicia faba to copper toxicity

S. Benouis1,2*, H.A. Reguieg Yssaad1, E.H. Bouziani1, I. Khedim1

1Laboratory of Biodiversity and Conservation of Water and Soils, Faculty of Nature and Life Sciences, University of Abdelhamid Ibn Badis, Mostaganem, Algeria
2Scientific and Technical Research Center on Arid Regions (CRSTRA) Biskra, Algeria

(Manuscript received 21 July 2020; accepted for publication 26 February 2021)


Abstract. Copper plays an important role in multiple plant physiological processes including photosynthesis and protein synthesis. Excess copper in tissues leads to physiological and biochemical disturbances. In order to determine the physiological response of Vicia faba L. to copper toxicity, two varieties (Sidi Aïch and Super Aguadulce) were grown in a substrate of sand and compost (3V/V) and contaminated by different doses of Cu (0, 80, 160, 240, 320, 400 mg kg-1). Dose rates ≥160 mg kg-1 led to the accumulation of copper in roots and shoots, in turn leading to decreases in photosynthetic activity and protein content and to the accumulation of proline, a stress indicator, and soluble sugars.

Productivity and feed quality of Sudan grass (Sorghum sudanense (Piper) Stapf.) and sweet sorghum forms

S. Enchev*

Agricultural Institute, 3 Simeon Veliki, 9700 Shumen, Bulgaria

(Manuscript received 24 August 2020; accepted for publication 22 February 2021)

Abstract. During the period 2017-2018, the feed quality and productivity of three Sudan grass varieties – Endje 1, Vercors and Super Sweet, one stabilized Sudan grass population – SWT, local sweet sorghum – „Zaharna metla“ population and the sweet sorghum cultivar “Shumensko sladko” were researched in Agricultural Institute – Shumen. Green mass (t/ha), dry matter (%) and dry mass production (%) as well as basic nutritional characteristics by the two swaths of the tested cultivars in brooming phase were controlled. It was found that the sweet sorghum cultivar “Shumensko sladko” gave the highest amount of green mass – 59.5 t/ha by two swaths, and the dry mass yield was the highest from the cultivar Endje 1 – 20.8 t/ha. In terms of chemical composition, the greatest variation was demonstrated in phosphorus content (0.369-0.696%, CV=27.3%), followed by crude fat (1.28-2.39%, CV=26.8%), Ca (0.889-1.572%, CV=21.8%), crude protein (6.05-9.00%, CV=14.6%), nitrogen free extracts (42.05-51.20%, CV=7.6%), crude fiber (32.64-39.26%, CV=6.1%) and mineral substances (8.17-9.61%, CV=5.9%). It can be summarized that all hybrids provide quality hay, however the Bulgarian cultivars Endje 1 and “Shumensko sladko” showed the best nutritional value – compared to Super Sweet, Vercors, SWT and “Zaharna metla”.

Influence of long-term fertilization and environments on test weight of durum wheat (Triticum durum Desf.) grain

G. Panayotova1*, S. Kostadinova2, S. Stefanova-Dobreva3, A. Muhova3

1Department of Plant production, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria
2Department of Agrochemistry and Soil Science, Faculty of Agronomy, Agricutural University, 4000 Plovdiv, Bulgaria
3Field Crops Institute, 6200 Chirpan, Bulgaria

(Manuscript received 6 September 2020; accepted for publication 26 February 2020)

Abstract. The aim of this study was to investigate the influence of long-term nitrogen-phosphorus fertilization and meteorological conditions during the period 1990-2019 on test weight of durum wheat grain in Central South Bulgaria. The influence of nitrogen and phosphorus rates – 0, 40, 80, 120 and 160 kg.ha-1, as well as combined NP fertilization in the same rates on durum wheat grain under conditions of stationary long-term fertilizing experiment in cotton-durum wheat crop rotation was studied. The analysis of the results showed that the test weight was below the standard requirements in eight of the studied years, and in 22 years the average test weight exceeded the requirements. The values in 17 years were over 80.0 kg. The test weight decreased by increasing the N rates above 80 kg and the lowest average value was seen at N160 – 79.4 kg. The Р application in rates from 40 tо 160 kg.ha-1 indicated a tendency to increase the test weight. Good values were realized by combining a moderate to high phosphorus rates Р80-160 with low N levels N40-80. Weather conditions during the 30-year period have a strong significant impact on the test weight of the grain.