Pepper is the second most important vegetable crop in Bulgarian agriculture and has become the subject of extensive breeding programs that frequently employ induced mutagenesis. The success of breeding programs can be enhanced by the efficient and integral application of different biochemical and molecular methods to characterize specific mutant alleles. On the other hand, identifying new cost-effective methods is important under a limited-resources environment. In this paper we compare the levels of five health-related carotenoid compounds of fruits (α-carotene, β-carotene, lutein, β-cryptoxanthin, zeaxanthin) between a mutant variety Oranzheva kapia (possessing high ß-carotene concentration) and a corresponding initial pepper variety Pazardzhishka kapia 794. Both varieties are intended for fresh consumption. Pepper is a major natural source of β-carotene. It was observed that fruit at both commercial and botanical maturity from mutant variety had greater α-carotene and β-carotene concentrations to the initial variety (7.49 and 1.94 times higher, respectively) meaning that the mutant was superior in fruit quality to the initial genotype. Two hydroxylase enzymes, converting α- and β-carotene to lutein and zeaxanthin, respectively, are known to exist in pepper and are encoded by two genes on chromosomes 3 and 6-CrtZ_chr03 and CrtZ_chr06. The molecular characterization of the mutant variety through locus-specific Polymerase chain reaction amplification, gene cloning and sequencing as well as expression was performed. Our results suggest that the increased ß-carotene accumulation in the mutant variety Oranzheva kapia results from a biosynthetic pathway breakdown due to deletion of CrtZ_chr03 gene.

In recent years, oriental tobacco varieties from the Krumovgrad ecotype have been among the most preferred by commercial companies in Bulgaria. The creating and study of genetic material with their participation is important to meet the needs and requirements of the sector. During a three-year period in the conditions of experimental field (EF) - Markovo were studied biometric (number of leaves, plant height, length and width of 14 and 21 leaves) and quality (yield and distribution by classes) indicators of four lines of oriental tobacco, created with the Krumovgrad ecotype participation. As control was used variety Krumovgrad 90. As a result of the studied biometric and qualitative indicators, it was established, that according to the indicators plant height, the studied lines are in the oriental tobacco range, but form a greater number of leaves from the control variety (the largest numbers of leaves and smaller by size in line 72). Line 71 has a statistically proven longest length on the 14th and 21st leaves. Lines 71 and 73 have the highest average yield (kg/da) for the three years and exceed the yield of the control variety by 10-15%. The class distribution results show, that lines 72 and 73 have the highest percentage of I-st class, and line 71 has the highest percentage of II-nd class and the lowest percentage of III- rd class. From the assessment made lines 71 and 73 have the best values of the biometric and quality indicators.

The green grasshopper (Tettigonia viridissima L.) is a species which attacks tobacco plants. The purpose of the present study was to establish the bio-insecticidal efficacy of entomopathogenic fungi Beauveria bassiana Vuill. strains 214, 644, and 733 on the growth and development of T. viridissima in tobacco. The research was conducted under laboratory conditions. The study found insecticidal effects of the B. bassiana strains 214, 644, and 733 against T. viridissima. Surviving of larvae was monitored at 5-day intervals until the 15th day after treatment with a spore suspension of the tested Beauveria strains. The highest virulence of the tested fungi was shown by strain 644, followed by strains 214 and 733. On the 5th day after treatment, no efficacy against T. viridissima larvae was detected. On the 10th day post-treatment strain 644 showed 66.7% efficacy, while efficacy against larvae of grasshoppers for the other two strains 214 and 733 was significantly lower: 33.3%. Efficacy gradually increased and on the 15th day post-treatment 100% mortality of T. viridissima was observed for all isolates. The results obtained from the virulence test of B. bassiana 214, 644, and 733 ascertain their application as biocontrol agents in tobacco production under field conditions.

Dry tobacco quality determined by the content of the main chemical indicators nicotine, total sugars, total nitrogen and the ratio between them. Strengthening regulations by the World Health Organization (WHO) to the chemical composition of tobacco, define the need to create a suitable breeding material. During the period 2020- 2022 in the Accredited Тesting Laboratory Complex at TTPI were determined the values of the main chemical indicators - nicotine, total sugars and total nitrogen in the first and second class dry tobacco from four oriental tobacco lines of the Krumovgrad ecotype, studied in the conditions on an experimental field (EF) - in Markovo village. Two controls from the Krumovgrad ecotype - variety Krumovgrad 90 and from the Eastern Balkan ecotype - variety Elenski 817 were used. The results show, the highest percentage of total nitrogen and nicotine, and respectively the lowest of total sugars, were reported in harvest for the 2021, characterized by higher average monthly temperatures and less rainfall during the plants vegetation period. According to the nicotine indicator, the studied lines (except for line 73) have average values between the two controls for harvests in the 2021 and 2022. The highest percentage of nicotine in 2020 and 2021, and an average of the three experimental years was reported in line 71, and the lowest in line 70. The lowest variation of the studied chemical indicators was established in line 71. The studied lines are valuable breeding material corresponding to the diverse needs of the tobacco industry.

In recent years, there has been increasing interest in identifying and studying beneficial microorganisms that can be used in organic farming as fertilizers and plant protection agents. Entomopathogenic fungi with an endophytic nature of the genus Beauveria are quite promising and their identification and detection in the plant and soil samples are of great importance. Molecular identification of fungi of the genus Beauveria was conducted by sequencing the internal transcribed spacer 1 and 5.8S ribosomal RNA gene (ITS) regions with universal primers. As a result of the sequencing, it was found that the analysed strains belong to four genera of Beauveria with the following percentage distribution: B. bassiana (68.18%), B. pseudobassiana (13.64%), B. varroae (9.09%) and B. tenella (9.09%). The largest percentages of the strains were identified as B. bassiana. Sequence-characterized amplified regions (SCAR) have been applied for the detection of Beauveria strains in the field samples. The efficiency and ability of three pairs of SCAR markers to differentiate the studied strains were tested. The applied SCAR markers generated fragments with expected length in more than 90% of the investigated strains and could be used as markers for the detection of the fungi from the genus Beauveria in field samples. In the selected experimental conditions only B. varroe 501 and B. tenella 593 lack fragments with used SCAR markers.

Фенолните киселини и флавоноидите са вторични метаболити, които изпълняват редица функции, част от които свързани със стреса и адаптацията на растенията към различни условия на околната среда. В настоящото изследване е проучено съдържанието на фенолни киселини и флавоноиди в български ориенталски тютюн в две последователни вегетационни години – 2023 г. и 2024 г., характеризиращи се с различни климатични условия, обуславящи необходимостта от различен брой поливки. Изследвани са общо 19 генотипа тютюн. Установена е промяна в съдържанието на фенолни киселини и флавоноиди през двете изследвани вегетации. Малко по-ниските температури и количества валежи, измерени през 2023 г., съчетани с по-малко на брой поливки, обуславят по-високото съдържание на фенолни киселини и флавоноиди, в сравнение с изследваните проби от 2024 г. Климатичните условия през 2024 г. са компенсирани с повече поливки по време на вегетацията. Това е една от вероятните причини, водещи до намаляване съдържанието на фенолни киселини и флавоноиди.