Bulgarian Cultivars Research Articles

Behaviour of some Bulgarian plum cultivars in the pedo-climatic conditions of the Pitesti – Romania area

In Romania and Bulgaria, plum is one of the most widespread species, both countries carry out a large breeding program. ‘Stanley’ is the most widespread cultivar in the plum orchards of both countries. Although it is a very productive cultivar, further requested by farmers, it presents some defects such as the low fruit quality and the sensitivity to Plum pox virus. That is why in both countries an improvement of the assortment was imposed by creating new cultivars in their breeding program, but also by introducing valuable cultivars obtained in other breeding centers from Europe. For this reason, researchers from both countries have changed biological material. In 2015, three Bulgarian cultivars were planted in a field trial by the Research Institute for Fruit Growing Pitesti, Romania. This paper aimed to evaluate the behaviour of these cultivars in climatic conditions from the Pitesti-Maracineni area. All Bulgarian cultivars were noted by good production, large fruits with high soluble solids content, as well as by tolerance to Plum pox virus. These cultivars can be recommended for extension in the commercial orchards from Romania, taking into account the requirements of the private fruit growers. Also, these cultivars can be used as genitors in breeding programs.

STABILITY AND ADAPTABILITY OF YIELD AND YIELD RELATED TRAITS IN BULGARIAN TRITICALE (×Triticosecale Wittm.) CULTIVARS IN DROUGHT CONDITIONS

To determine the adaptability and stability of yield and its related traits during drought conditions in triticale, eleven contemporary Bulgarian cultivars were studied according to the indices yield, number of productive tillers, 1000 kernel weight and number of grains in spike, applying four parameters: regression coefficient and deviation from regression, ecovalence and stability variance of Shukla. Drought had a significant effect on the yield related traits, which differed considerably according to the different parameters of stability. The best combination of stability and adaptability according to number of productive tillers and 1000 kernel weight was observed in Bumerang and Doni 52. The parameter number of grains in spike behaved in a rather complex manner under conditions of drought and the separate stability parameters related to contradictory results. The widest adaptability according to this parameter was observed in cultivars Rakita, Lasko and Respekt. The stability and adaptability parameters of the separate yield traits was not functionally related to the same parameters of yield, which determined the investigated cultivars as developed according to a complex of traits and being suitable for growing under variable environments.

Insertion of a mMoshan transposable element in PpLMI1, is associated with the absence or globose phenotype of extrafloral nectaries in peach [Prunus persica (L.) Batsch

Most commercial peach [Prunus persica (L.) Batsch] cultivars have leaves with extrafloral nectaries (EFNs). Breeders have selected this character over time, as they observed that the eglandular phenotype resulted in high susceptibility to peach powdery mildew, a major disease of peach trees. EFNs are controlled by a Mendelian locus (E), mapped on chromosome 7. However, the genetic factor underlying E was unknown. In order to address this point, we developed a mapping population of 833 individuals derived from the selfing of "Malo Konare", a Bulgarian peach cultivar, heterozygous for the trait. This progeny was used to investigate the E-locus region, along with additional resources including peach genomic resequencing data, and 271 individuals from various origins used for validation. High-resolution mapping delimited a 40.6 kbp interval including the E-locus and four genes. Moreover, three double-recombinants allowed identifying Prupe.7G121100, a LMI1-like homeodomain leucine zipper (HD-Zip) transcription factor, as a likely candidate for the trait. By comparing peach genomic resequencing data from individuals with contrasted phenotypes, a MITE-like transposable element of the hAT superfamily (mMoshan) was identified in the third exon of Prupe.7G121100. It was associated with the absence or globose phenotype of EFNs. The insertion of the transposon was positively correlated with enhanced expression of Prupe.7G121100. Furthermore, a PCR marker designed from the sequence-variants, allowed to properly assign the phenotypes of all the individuals studied. These findings provide valuable information on the genetic control of a trait poorly known so far although selected for a long time in peach.

POMOLOGICAL CHARACTERISTICS OF LOCAL AND INTRODUCED WALNUT CULTIVARS IN SOUTH BULGARIA

A study of local and introduced walnut cultivars was carried out at the Fruit-Growing Institute – Plovdiv in the period 2018 – 2020. Four introduced walnut cultivars – two Romanian (‘Valmit’ and ‘Valeris’) and two Turkish (‘Şebin’ and ‘Yalova 1’) – and the standard Bulgarian cultivars ‘Izvor 10’ and ‘Silistrenski’ were the object of the study. Their vegetative habits were investigated and biometric measurements of the nuts were performed. Based on the results obtained the pomological characteristics of the studied cultivars were evaluated. When grown in the conditions of South Bulgaria, the cultivars introduced from Romania – ‘Valmit’ and ‘Valeris’ and from Turkey – ‘Yalova 1’, are characterized by very large nuts. ‘Izvor 10’ and ‘Şebin’ have a high kernel ratio.

Antioxidant properties of pepper (Capsicum annuum L.) depending on its cultivar and fruit colouration

Due to its nutritional, health-promoting and taste-related values, new cultivars are introduced every year. The aim of the study was to assess the biological value of Polish and Bulgarian cultivars of pepper grown in moderate climate conditions and collected at different degrees of maturity. Ascorbic acid, carotenoids, polyphenols, chlorophyll a, chlorophyll b, total chlorophyll and antioxidant activity (DPPH) were determined in air-dried fruit. The investigation included five Polish cultivars: Roberta, Marta Polka, Etiuda, Trapez, and Cyklon and five Bulgarian cultivars: Bulgarski Ratung, Sivriya, Kurtovska Kapiya, Delikates, and Dzuliunska Shipka. Its design involved randomised sub-blocks, with three replications comprising nine plants each. The area of a single plot was 1.44 m<sup>2 </sup>(1.2 m × 1.2 m). The study confirmed the strong antioxidant properties of pepper grown in the field, without cover, and under temperate climate conditions. The vegetable is rich in vitamin C, polyphenols, carotenoids, chlorophyll pigments, and shows high antioxidant activity. However, the biological value of pepper is cultivar-dependent and is also determined by the fruit colouration degree. The coloured fruits are richer in vitamin C and carotenoids than the green ones, and when matured, they have greater antioxidant capacity. Green fruits contain more chlorophyll a, chlorophyll b and total chlorophyll than the coloured ones. The fruits of cv. Etiuda were the richest in vitamin C, of cv. Sivriya in polyphenols, of cv. Dzuliunska Shipka in carotenoids, and of cv. Trapez in total chlorophyll. Cv. Sivriya showed the strongest antioxidant properties.

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

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”.

Adaptation potential of <i>Ficus carica</i> L. in summer dry conditions

During the summer season, on the southern coast of Crimea, the parameters of the water regime of 6 varieties of Ficus carica L. of various origins were studied. As a result of a comparative assessment of the experimental indicators, potentially adaptive, resistant to stressful weather factors, genotypes were identified - 'Sabrutciya Rosovaya' of the Nikitsky Botanical Garden selection, an introduced plant from Bulgaria 'Ranniy is Sozopoliya'. These cultivars have demonstrated high water-retention forces and the possibility of the most complete repair of leaf tissues. A relatively weak ability to retain moisture and restore turgor after dehydration was shown by the cultivar Vladimirska Krupna introduced from Yugoslavia and the Bulgarian cultivar Pomoriyskiy 6.

Molecular Diversity of Walnut (Juglans regia L.) Among Two Major Areas in Morocco in Contrast with Foreign Varieties

ABSTRACT In Morocco, walnut tree (Juglans regia L.) cultivation is ancestral with complicated misidentification and unknown local genetic diversity. Atlas Mountains host a rich walnut tree germplasm, which has arisen from seedlings. The use of molecular markers makes it possible to overcomes confusion usually encountered in phenotypic characterization, thereby elucidating the real genetic diversity magnitude. This study aimed to investigate the genetic relationships among 33 local walnut trees grown in two contrasted agroecosystems, while comparing them with 8 Bulgarian varieties belonging to an ex-situ collection, using ISSR markers. The use of 13 primers generated 120 reproducible ISSR markers, with 7 to 13 bands and an average of nine bands per primer. This number reflected the high level of polymorphism between genotypes revealed by the selected primers. The average polymorphism rate was 75.2%, with the polymorphic information content varying from 0.212 to 0.370 and with an average of 0.32. Genetic distances and the pairwise comparison showed that all pairs of genotypes are distinct using more than 10 markers with a maximum of 50 bands. The dendrogram showed an obvious phylo-geographic structuring and the differentiation of genotypes by origin area. The Bulgarian cultivars form distinct groups that confirms the specificity of the Moroccan walnut gene pool. However, the dendrogram obtained showed that the Moroccan genotypes are genetically close to a certain number of Bulgarian genotypes. This indicates that some Moroccan genotypes and the Bulgarian varieties could have a common ancestor.

Peculiarities in the Structure of Yield in Common Wheat Accessions from Different Ecological and Geographic Origin

Dobrudzha Agricultural Institute (DAI) is the largest breeding center for cereals in Bulgaria. Among the varieties developed here, 36 genotypes were included in the national list, a large part of them being strong and medium strong wheat cultivars with increased strength. It is a disputable question if a plateau has been reached in the breeding of wheat and what are the further methods for increasing of the production potential. Until recently, the increasing of the spike productivity lay at the basis of the breeding strategy, primarily through a higher number of florets and grains formed per spikelet at the expense of a lower number of productive tillers. The contemporary high level of breeding and the market requirements impose the necessity to search for new approaches to increase productivity. The aim of the investigation was to characterize the structure of the yield in new common winter wheat accessions included in the gene pool of DAI. The investigation was carried out during 2015 – 2019 and encompassed four growth seasons with different combinations of meteorological factors allowing for good differentiation. The trial was designed in two replicates, the size of the harvest plot being 10 m2. Sixty-six accessions from different ecological and geographic origin and with specific combination of the economically important traits were evaluated. The cultivars from France were with the highest coefficient of tillering, followed by the cultivars from Croatia and Germany. The variability with regard to 1000 kernel weight was considerable. The Bulgarian and Serbian accessions were with the highest absolute weight, and the French ones – with the lowest. The differences with regard to the number of grains in spike were significant at a high level, but in the separate group, Athlon (DE), Moison (F), Fani (BG), Fidelius (AT), Iveta (BG) Korona (BG) and Simonida (RS) were with high values of the trait. Within the period, the Bulgarian cultivars, which realized highest yield, were Rada and Dragana, and among the European ones, these were Andalou, Basmati, NS 407 and Sofru.

Macro- and micronutrient content in selected cultivars of Capsicum annuum L. depending on fruit coloration

Capsicum annuum L. belongs to the Solanaceae family and is a species of huge economic importance and high nutritional value. A study conducted in the years 2014–2015 at the Department of Horticulture, West Pomeranian University of Technology in Szczecin, assessed the content of macro- and micronutrients in the fruit of selected Polish and Bulgarian cultivars of pepper collected at different stages of coloration development. The investigation included five Polish cultivars: Roberta, Marta Polka, Etiuda, Trapez and Cyklon and five Bulgarian cultivars: Bulgarski Ratung, Sivriya, Kurtovska Kapiya, Delikates and Dzuliunska Shipka. The study demonstrated a significant effect of cultivar and a degree of fruit coloration on the content of dry matter and macro- and micronutrients. The coloured fruits featured higher content of dry matter than the green ones and cv. Etiuda had the greatest dry matter. Green fruits contained more Mg, Mn and Zn, while the coloured ones more Ca and Fe. Cvs. Delikates and Dzuliunska Shipka were particularly rich in Mg and K, cv. Sivriya in Ca and cv. Etiuda in P, Cu, Zn and Mn were the most abundant in cv. Delikates, Fe in cv. Trapez, and Na in cv. Cyklon.

Pomological studies of Bulgarian cultivars and forms of cornelian cherry (Cornus mas L.)

Pomological studies of Bulgarian cultivars and forms of cornelian cherry (<i>Cornus mas</i> L.)

Influence of genotype and crop year on carotenoids content of peels from Bulgarian tomato cultivars

Influence of genotype and crop year on carotenoids content of peels from Bulgarian tomato cultivars

Enzyme-assisted extraction of carotenoids from Bulgarian tomato peels

Enzyme-assisted extraction of carotenoids from tomato peels of the Bulgarian cultivar “Stela”, one of the most widely used cultivars by the canning industry, was examined in this study. The carotenoid content in raw tomato peels was established by HPLC analysis. A two-step protocol was followed: the tomato peels were first treated with enzymes and then extracted by the use of acetone as a solvent for 30 min at 20±1 °C and solid/liquid ratio of 1:30. The total carotenoid, lycopene, and β-carotene extraction yields were increased by the use of pectinase, cellulase, endo-xylanase, and proteinase enzymes in comparison with the non-enzyme-treated samples. The increase in the extraction yield was affected by the enzymes used, the enzyme concentration, the pretreatment time and temperature. Maximum total carotenoid (55.15 mg/100 g d.w.), β-carotene (35.85 mg/100 g d.w.), and lycopene (15.44 mg/100 g d.w.) extraction yields were obtained in peels pretreated with mixed cellulase (100 U g−1) and endo-xylanase (400 U g−1) for 4 h at 50 °C. Carotenoid recovery by mixed cellulolytic and hemi-cellulolytic enzyme pretreatment of tomato peels is a good approach, which can be used for waste utilization.

Evaluation of diversity in Bulgarian pepper cultivars by agronomical traits and ISSR markers

Information about the genetic variation among cultivars of vegetable crops is of vital importance for improvement of plant breeding programmes worldwide. The objectives of this study were to group 19 pepper (Capsicum annuum L.) cultivars from the collection of Maritsa Vegetable Crops Research Institute, Plovdiv, Bulgariainto clusters according to their distances as estimated by agronomic traits and 9 di-and tri -nucleotide inter simple sequence repeat polymorphism (ISSR) markers and to assess the relationships between them. The phenotypic characterization during 3 consecutive years revealed significant differences among Bulgarian cultivars for the studied 13 phenotypic traits. The biplot analysis of quantitative traits showed that the most strongly correlating traits with the first axis (55.6% of variance) were fruit width, fruit weight and pericarp thickness (in the negative direction of the axis), and plant height (PH) (in the positive direction). The most discriminative traits, considering the second axis (22.6% of variance) were fruit length (FL) and to a lesser extent the stem height (StH). The correspondence analysis of the qualitative traits showed that the intensity of the colour of the fruit (before and at maturity), fruit colourbefore maturity and fruit shape in longitudinal section were the most discriminative characteristics for the first two dimensions. The agronomic traits data and 7 dinucleotide ISSR primers were used to estimate the pairwise genetic distances. Higher mean phenotypic distance (0.414) in comparison to the genotypic ones (0.214) among the cultivars was observed, indicating higher phenotypic diversity among them. A highly signi?cant, positive correlation between the agronomic data and ISSR marker-based matrices (r=0.41, p=0.001)was detected. This indicates that ISSR distance tended to re?ect that of the agronomics ones. However, additional molecular studies and large collection of highly diverse genotypes are needed to reveal associations between the marker loci and specific QTLs. The research initiated is a base for more precise estimation of genetic distances between pepper genotypes from the available large collection of landraces, local and modern cultivars including large number of highly polymorphic markers.

‘Evmolpiya’ – a new Bulgarian peach cultivar resistant to leaf curl disease (Taphrina deformans)

‘Evmolpiya’ – a new Bulgarian peach cultivar resistant to leaf curl disease (<i>Taphrina deformans</i>)

Response of Pea Varieties to Damage Degree of Pea Weevil, Bruchus pisorum L.

A study was conducted to determine the response of five pea varieties (Pisum sativum L.) to damage degree of Bruchus pisorum: Glyans, Modus, Kamerton, and Svit (Ukrainian cultivars) and Pleven 4 (Bulgarian cultivar). The seeds were classified into three types: healthy seeds (type 1), damaged seeds with parasitoid emergence hole (type 2), and damaged seeds with bruchid emergence hole (type 3) and they were sown. It was found that the weight of 1000 seeds did not affect the field germination of the pea varieties. Healthy and damaged seeds with parasitoid emergence holes (first and second seed types) provide a very good opportunity for growth and development while plants from damaged seeds with bruchid emergence holes had poor germination and vigor and low productivity. These seeds cannot provide the creation of well-garnished seeding and stable crop yields. Among tested varieties, the Ukrainian variety Glyans had considerably higher seed weight, field germination, and index germination and weak egg-laying activity of B. pisorum compared to others. Use of spring pea cultivars that are weakly preferred by the pea weevil in breeding programs would reduce losses due to pea weevil and provide an environmentally safer option to its control.

Genotype-environment interaction and stability analysis for seed yield in vetch (Vicia sativa L., Vicia villosa Roth.)

During the period 2012 -2014 was conducted a field trial with seven vetch cultivars: six Moldavian cultivars Liya, Lorina, Vilena, Moldovskaya (belonging to Vicia sativa L.), Violeta and Viola (belonging to Vicia villosa Roth.) and one Bulgarian cultivar Obrazets 666 (belonging to Vicia sativa L.). The performance, adaptability and stability of the tested cultivars were determined in relation to plant height (cm), stem (mm) and length (cm) of the pod, number seeds and pods per plant, number seeds per pod, 1000 seed weight (g), seed weight per plant (g) and seed yield (kg da-1). Traits such as plant height, pods per plant, seeds per plant, 1000 seed weight and seed yield showed a significant genotype × environment interaction which shows the participation of different gene systems in their control. In regard of these traits were calculated parameters of phenotypic stability and selection-valuable genotypes were determined. The cultivar Moldovskaya could be considered close to the ideal type (bi ≈ 1.0), suitable for growing over a wide range of environment. Liya and Obrazets 666 were determined as unstable (bi > 1) but with good responsiveness, providing them high yields at moderate environmental conditions. Cultivars Liya and Obrazets 666 could be defined as stable and with good responsiveness (bi = 1.07 - 1.11), but because of lower yields they do not have priority over others. From viewpoint of selection, cultivars Moldovskaya, Liya and Obrazets 666 are suitable for including in breeding programmes and developing new vetch lines with high and stable yields

Osmoregulation capacity in Bulgarian durum wheat

The phenotypic variation in osmotic adjustment (OA) capacity of five Bulgarian winter durum wheat genotypes and their progenies was determined using a modified method based on the measurement of seedling growth suppression after three-day exposure to osmotic stress induced by 1 mol/L sucrose. The genetic parameters of the studied trait in a diallel crossing scheme, including the selected genotypes and the microsatellite polymorphism at 43 loci, were determined. The old Bulgarian cultivar Apulicum 233 and all hybrid combinations involving this genotype showed higher OA. In the heritability of osmoregulation ability, the non-additive gene effects (specific combining ability) strongly predominated over the additive ones and had a significant impact on the observed high heterosis effect. Distinct polymorphisms were identified between the studied genotypes. Cluster analysis of the phenotypic data obtained from a multiyear test under water-limited conditions and the molecular data, both based on Euclidean distance, showed similar grouping of the genotypes with specific separation of cultivar Apulicum 233 (high OA) in a single cluster. Principal component analysis revealed not only interrelationships between the important agronomic and morpho-physiological traits in Bulgarian durum wheat under water-limited conditions, but also presence of relations between them and some microsatellite loci located near or within known quantitative trait loci (QTLs) for these traits. Further studies based on segregating population between genotypes with contrasting levels of OA will allow mapping QTLs for phenotypic traits expressed under water deficit and isolation of genes that can be used as potential markers in marker-assisted selection for drought tolerance.

Physiological and anatomical responses of wheat to induced dehydration and rehydration

Abstract Hydroponically grown wheat seedlings of two prominent Bulgarian cultivars (Katya and Prelom) were subjected to 48 h osmotic stress with PEG 8000 and were then rehydrated. The degree of stress was evaluated by monitoring relative water content, lipid peroxidation level, and accumulation of free proline and hydrogen peroxide in the leaves. Anatomy and ultrastructure of leaf tissue were observed under light microscopy. After imposition of stress, drought tolerant cultivar Katya displayed higher free proline content and significantly lower malondialdehyde and peroxide concentration in leaves than in the leaves of susceptible cultivar Prelom. After 24 h of rehydration Katya showed better ability to restore leaf water status and an apparent tendency towards recovery, whereas Prelom sustained higher levels of hydrogen peroxide, lipid peroxidation products and free proline and markedly low relative water content. Here, we have uncovered some of the characteristics displayed by cultivar Katya that enable it to survive and recover from severe osmotic stress. Interestingly, there was congruence between our results and the high level of cultivar Katya drought tolerance observed in the field.

Expression of recombinant human lactoferrin in transgenic alfalfa plants

In order to produce human lactoferrin (Lf) in alfalfa (Medicago sativa L.), a construct containing human Lf cDNA under the control of cauliflower mosaic virus 35S promoter was engineered. As selectable marker bar gene, whose expression in plant cells confers tolerance to L-phosphinothricin (ppt) was used. Plants from a highly embryogenic alfalfa clone from the Bulgarian cultivar Obnova 10 were transformed using Agrobacterium tumefaciens mediated leaf disc method. Transgenic alfalfa plants were established from ppt-resistant calli via indirect somatic embryogenesis. The presence of human Lf cDNA in the genome of the selected regenerants was confirmed by polymerase chain reaction (PCR). Reverse transcriptase (RT)-PCR and Western blot showed expression of human Lf in leaf tissue. Studies on antibacterial effect of the recombinant glycoprotein were conducted and resistance of the transgenic alfalfa plants to two phytopathogens, Pseudomonas syringae pv. syringae and Clavibacter michiganensis, was demonstrated. The obtained results suggest that the expression of human Lf in alfalfa could be beneficial not only for producing recombinant protein for clinical application but also for crop quality improvement.