Sweet cherry forms obtained with embryo culture techniques and their study in the Crimean steppe

Background. Sweet cherry plants bear fruit annually, are high-yielding, and generate good profits. Cultivars with early-ripening fruits are specially valued. Cultivation of such sweet cherries makes it possible to extend the period of fresh fruit consumption and increase the profitability of orchards. It is therefore relevant to breed new early-ripening cultivars of this fruit plant.   Materials and methods. Twenty sweet cherry forms from five hybrid families obtained with in vitro embryo culture techniques at the Nikita Botanical Gardens were analyzed. The original early-ripening cultivars included in the hybridization of ‘Durona di Vignola 2’ and ‘Zemfira’ were used as a control. Flowering dates, fruit ripening dates, fruit weight and quality, resistance to negative temperatures (down to –25.6°C), and susceptibility to fungal diseases were studied from 2012 to 2021 at the Steppe Horticulture Laboratory, Nikita Botanical Gardens, using conventional methods.   Results and conclusions. Late-flowering breeding forms 460, 597, 602, 612 and 843 were selected for their lowest susceptibility to the effects of late spring frosts. Forms 343, 366, 453, 459, 460, 602, 612, 653, 353, 387, 600, 653 and 843 had early and very early fruit ripening periods. Forms 320, 434, 460, 593a, 597, 600, 601, 602 and 607 were identified for their high yields. Genotypes 459, 460, 601 and 843 demonstrated resistance to Cylindrosporium hiemale Higg., and 597, 843 and 320 to Monilia cinerea Bonord. High winter hardiness and frost resistance was observed in forms 355, 434, 459, 597 and 602. Breeding forms 460, 602 and 843 were identified as promising for a set of traits (late flowering, large high-quality fruits, resistance to major diseases, and high yield). They are of interest for introduction into horticultural production and use in further breeding work to develop new competitive cultivars

Features of the water regime and photosynthesis in hybrid forms of cherry plum under the dry wind season conditions

Background. The results of a study on the drought resistance of cherry plum hybrid forms are presented. Water retention capacity of leaves and chlorophyll fluorescence were measured under the simulated conditions close to the dry wind season.Materials and methods. The water regime parameters were studied for five cherry plum genotypes in 2021 and 2022. Leaves of four hybrid forms developed at the Nikita Botanical Gardens and the reference cherry plum hybrid cultivar ‘Rumyanaya Zorka’ (Prunus rossica Erem.) were taken into the experiments. Using the guidelines by G. N. Eremeev and A. I. Lishchuk, a series of experiments on controlled leaf wilt at the air temperature of +27°C and relative humidity of 30% were conducted on cherry plum to assess the functional state of the photosynthetic apparatus during the development of water stress under dry wind conditions. The experiments were carried out in a Binder climate chamber. Chlorophyll fluorescence was measured using a portable Floratest fluorometer. The measurements were based on the parameters of the chlorophyll fluorescence induction curve (CFI) obtained on native leaves. The leaves of cv. ‘Rumyanaya Zorka’ in the state of complete watering served as the reference.Results and discussion. Dependence was identified between chlorophyll fluorescence and moisture content in the leaves of the studied samples. The hybrids were found to respond to drought in different ways. A relatively increased ability to retain moisture during dehydration was observed in form 12/26 whose leaves gave off moisture more slowly and restored their turgor better. It is promising for cultivation in areas with insufficient water supply. Form 99/36 had the lowest potential drought resistance. Forms 99/14 and 9/28 occupied an intermediate position

Features of developing SARS-CoV-2 nucleocapsid protein population-based seroprevalence during the first wave of the COVID-19 epidemic in the Russian Federation

The novel coronavirus (SARS-CoV-2) pandemic, dubbed COVID-19, has become one of the most serious challenges for human populations in the vast majority of countries worldwide. Rapid spreading and increased mortality related to it required new approaches to manage epidemic processes on a global scale. One of such approaches was based on analyzing SARS-CoV-2 seroprevalence associated with COVID-19. Our aim was to summarize the results on assessing seroprevalence to the SARS-CoV-2 nucleocapsid antigen (Nc) in residents from 26 regions of the Russian Federation, carried out during the first wave of the COVID-19 epidemic.Materials and methods. Seroprevalence distribution was examined in 26 model regions of the Russian Federation according to the unified method developed by the Rospotrebnadzor with the participation of the Federal State Institution Saint Petersburg Pasteur Research Institute of Epidemiology and Microbiology. Such approach implied formation of a group of volunteer subjects in model geographic region who were tested by ELISA for anti-Nc serum antibody level in peripheral blood. Analyzed primary data obtained in separate regions were either accepted for publication or released.Results. The current paper finalizes the data obtained in all 26 regions of the Russian Federation. The total SARS-CoV-2 seroprevalence was 19.5 (10.0–25.6)% with the maximum and minimum value found in the Kaliningrad Region and the Republic of Crimea, respectively (50.2% vs. 4.3%). A pattern of age-related seroprevalence distribution indicates insignificant predominance of seroprevalence among subjects of 1–17 years old: 22.1 (13.1–31.8)%. Among COVID-19 convalescents positive for SARS-CoV Nc antibodies it reached 60.0 (40.0–73.3)%. The number of contact persons comprised 6285 subjects or 8.5% of total volunteer cohort, with the level of seroprevalence reaching up to 25.3 (17.95–35.8)%. A direct correlation was revealed between levels of seroprevalence in convalescent and contact volunteers. In addition, the reproductive number for SARS-CoV was calculated comprising 5.8 (4.3–8.5) suggesting that one convalescent subject can infect at least 4 healthy individuals. A high level of asymptomatic forms of COVID-19 among seropositive subjects was confirmed empirically comprising up to 93.6 (87.1–94.9)%.Conclusion. A single cross-sectional study performed during 2020 June–August timeframe allowed to assess pattern of sex- and agerelated COVID-19 seroprevalence for general population in 26 Russian Federation regions. The data obtained may serve as a basis for the longitudinal cohort investigation with serial subject sampling. The timing and duration of study will be determined by dynamics of ongoing COVID-19 epidemic

Fragmentation and Multifragmentation of 10.6A GeV Gold Nuclei

We present the results of a study performed on the interactions of 10.6A GeV gold nuclei in nuclear emulsions. In a minimum bias sample of 1311 interac- tions, 5260 helium nuclei and 2622 heavy fragments were observed as Au projec- tile fragments. The experimental data are analyzed with particular emphasis of target separation interactions in emulsions and study of criticalexponents. Multiplicity distributions of the fast-moving projectile fragments are inves- tigated. Charged fragment moments, conditional moments as well as two and three -body asymmetries of the fast moving projectile particles are determined in terms of the total charge remaining bound in the multiply charged projectile fragments. Some differences in the average yields of helium nuclei and heavier fragments are observed, which may be attributed to a target effect. However, two and three-body asymmetries and conditional moments indicate that the breakup mechanism of the projectile seems to be independent of target mass. We looked for evidence of critical point observable in finite nuclei by study the resulting charged fragments distributions. We have obtained the values for the critical exponents gamma, beta and tau and compare our results with those at lower energy experiment (1.0A GeV data). The values suggest that a phase transition like behavior, is observed.Comment: latex, revtex, 28 pages, 12 figures, 3tables, submitted to Europysics Journal

Angular distributions in proton-nucleus interactions in emulsion at 800 GeV

Data on angular distributions of heavily ionizing and shower particles in incoherent protonnucleus collisions in emulsion at 800 GeV are reported and discussed in details. Dependence of angular distributions on the mass number of a target nucleus and on the multiplicity of charged particles is investigated. The data presented are systematically compared with results of emulsion experiments at lower energies and with predictions of the Lund Monte Carlo model FRITIOF. © 1988 Springer-Verlag