Relevance. Shallots are an independent botanical species. It easily crosses with onions, has a medium-sized bulb, keeps well, gives rich greens. Shallot and onion hybrids have a higher yield, less nesting, and a large bulb mass. Work on the creation of interspecific hybrids of shallots and onions has been under way since 2000.Methods. The aim of the research was to study the hybrids of Allium ascalonicum L. x Allium cepa L. and Allium cepa L. x Allium ascalonicum L. by a complex of characters in comparison with their maternal forms. Samples from the Urals were taken as initial forms for hybridization.Results. 268 promising hybrids were obtained, of which 33 were selected for further study. The results of the study showed the advantage of hybrid forms, where shallots were the parent form. A significant advantage of hybrids over parental forms was revealed in terms of yield, average and maximum bulb weight.

Relevance. Plant growth biostimulants based on natural raw materials are ecologically safe and harmless to humans. Stevia (Stevia rebaudiana Bertoni) contains in its leaves sweet diterpene steviol glycosides, which are similar in structure and properties to gibberellins, as well as a number of other valuable biologically active compounds. Water extracts from stevia leaves are capable to accelerate growth, to increase the yield and quality of plants. However, further study and development of application technologies of the extracts for specific crops and different growing conditions are required. The purpouse of this work is to investigate the effect of an aqueous extract from stevia leaves on the yield and quality of lettuce and small radish under photoculture conditions. Materials and methods. The objects of the study were lettuce var. Typhoon and small radish var. Riesenbutter. The plants were grown in photoculture at the biopolygon of the FSBSI Agrophysical Research Institute (St. Petersburg) at an illumination of 10–20 klx, a temperature of 22–26°С (day) and 18–20°С (night). Watering was carried out with water, top-dressing was carried out with Knop's nutrient solution three times a week. Peat with mineral additives was used as a substrate. The original extract was prepared by extraction from stevia dry leaves powder with hot water (80°С) in a ratio of 1 g of leaves: 100 ml of water. Foliar treatment of plants was carried out twice at dilution of the original extract from stevia leaves 1:10, 1:50, and 1:100 (extract : water) at the rate of 0.20-0.25 ml / lettuce plant and 0.09-0.1 ml / radish plant; control plants were treated with water. The data were processed according to standard procedures using the Excel 2016 software. Results. Foliar treatment with an extract from stevia leaves did not significantly affect the size and weight of radish root crops, but increased the yield due to a decrease in the number of bolting plants. A significant decrease of bolting was observed in all treatment options (by 34-51%). When using a dilution of 1: 100, the yield of marketable root crops increased by 20% and the yield per sq. m. – by 25%. Foliar treatment with stevia extracts increased the mass of lettuce plants, as well as their biological value. The content of photosynthetic pigments, sugars, and vitamin C significantly increased, and a tendency towards a decrease in the content of nitrates was observed. According to data, we recommend for foliar treatment are dilutions of the original extract 1:50 and 1: 100. The effect of using of an extract from stevia leaves is similar in action to some biostimulants from plants with hormone-like properties, which determines the possibility of using it as a safe plant growth stimulant.

Relevance. In the Republic of Moldova in recent years, during tomato flowering, air temperature reaches 35°С and higher, which significantly reduces fruit set, yield and product quality, therefore, the creation of varieties resistant to temperature stress is of particular importance. The relevance of the studies is due to the need to identify tomato genotypes resistant to high temperatures, to identify the genetic nature of the variability and degree of inheritance of tomato growth organs when interacting with different temperature conditions. The purpose of the research is to determine the effect of stress temperatures on the organs of growth and development of tomato plants at an early stage of ontogenesis, the degree of genetic, phenotypic variation and inheritance of characters. Materials and methods. The research material was 5 promising lines of tomato with high economically valuable traits. As a standard, a omologated variety Mary Gratefully was used. Four temperature levels were used – optimal (25°С) and stress (38, 40 and 42°С). The length of the germinal root and stem of 7-day-old plants was measured. The experiment was made in 3 replicates. The following were studied: genetic and phenotypic variants, heritability coefficient, phenotypic and genotypic coefficients of variation, genetic progress. The data were processed in the STATISTICA 7 software package. Results. As a result of the studies, a significant differentiation of the reaction of tomato genotypes to temperature stress was revealed. A significant effect of temperature on the genetic and phenotypic varieties of signs of growth and development of tomato plants, heritability in the broad sense, genotypic and phenotypic coefficient of variation, and genetic progress have been established. Of a great interest for further studies are the Mary Gratefully, L 304, L 306 genotypes, which are highly resistant to the studied traits.

Relevance. Currently, downy mildew of cucumber (peronosporosis) is the most harmful disease on this crop in the open ground, has an epiphytotic character and causes significant damage to the crop of greens. Material and methods. The research was carried out on selection and collection material of the laboratory of selection and seed production of pumpkin crops in the open and protected ground of the Moscow region. At least 300 collection and selection samples of cucumber were sown in the open and protected ground (Moscow region) every year, for phytopathological evaluation. Their defeat by downy mildew was taken into account on a 5-point scale. Results. Among the varieties of FSBSI FSVC selection, were less affected by this disease: Edinstvo, Electron 2, Vodoley, Vodopad, F1 Debut, F1 Krepish, F1 Brunette, F1 Frant, F1 Krasotka and F1 VNIISSOK 1. The most resistant to peronosporosis were Japanese varieties – Sadao rishu, Jibai, Higan Fushinari, Tropical slicer and others. Some Polish hybrids – Aladyn (SKW 190), Heron (SKW 290) and Parys (SKW 390), also had increased resistance to downy mildew. It should be noted that the varieties Jerelo and Geim from Ukraine; Dutch hybrids – F1 Sequenza, F1 Bejo 1612, F1 Pontia, 85/2292, F1 Donia mix; from the United States – F1 Calypso. In the selection for resistance to downy mildew you can to use varieties created in the Far East, the Crimean experimental breeding station. As a result of the annual assessment of parent forms on a natural infectious background, samples with increased resistance to downy mildew were selected.

Relevance. One of the conditions for creating a modern high-tech hybrid of sweet pepper is the presence of resistance to the Pepper mild mottle virus (PMMoV). This virus belongs to the genus Tobamovirus. This virus can spread through seeds, causing enormous damage to the sweet pepper crop. The main method of controlling of virus is the cultivation of F1 hybrids of pepper with genetic resistance. To date, the L4 gene is able to confer resistance to all known strains of this virus. However, there is still no reliable marker system that could be integrated into the MAS. Methods. Based on data from the NCBI, we generated a molecular diagnostic system based on hybridization probes. Validation was performed on seven pepper accessions from the world's germplasm banks. After validation, the new marker was successfully tested on 2540 plants of F2 and F3 generation. Results. Using the experimental marker system Fret4, we tested 7 reference samples of pepper germplasm with full correspondence of the melt peaks to the declared alleles of the L gene (L0/L1/L3/L4). Then, using a marker system, MAS was carried out on 10 populations of an number of 10 thousand plants to identify the L4 allele. As a result, we were able to create a highly accurate and cost-effective marker system for the most important pepper resistance gene. This marker system based on hybridization probes is easily integrated into the MAS, allowing fast and reliable determination of the L4 allele state in sweet pepper breeding to Tobamovirus.

Relevance and methods. Pumpkin fruits and seeds are valuable raw materials for the food and pharmaceutical industries. Of particular value are pumpkin seeds, from which oil and protein products are obtained. The purpose of our research is to identify the best breeding samples of pumpkin in terms of seed yield and pumpkin oil and to study their biochemical composition. The evaluation of 12 samples of pumpkin was carried out according to the main economic and biological characteristics. Results. According to the yield of seeds and the yield of pumpkin oil, the following samples were distinguished: Delta, Golosemyanno-kustovaya, Line 2-3, Line 2-5. The biochemical composition of seed samples with high seed yields was studied in terms of the content of proteins, fats, carbohydrates, amino acids, fatty acids, vitamins and minerals. A biochemical analysis of pumpkin seed oil for fatty acids, sterols and minerals was carried out. Seeds of hard-barked pumpkin of Belarusian selection are sources of high protein content (34-35%) with a wide range of essential amino acids, fats (43-45.8%), unsaturated and saturated fatty acids, as well as carbohydrates (9.6-11.9%) , a number of vitamins, macro- and microelements.

Relevance. A study of the seasonal (phenological) phenomena and natural connections between them on the background of the relevant environmental conditions is of great scientific and practical interest. Knowledge of the dynamics of the seasonal development of woody plants helps in the selection of species and their assessment from an aesthetic and sanitary points of view, as well as in the development and implementation of measures to increase the sustainability of urban green spaces. Materials and methods. The purpose of these studies is to create a database of the dynamics of seasonal development of North American woody plants based on the results of many years of phenological monitoring (2003-2017). The 20 species and forms of North American woody introducers e of the VNIISPK arboretum genetic collection were the objects. Results. It was revealed that the growing season of woody North American plants corresponds to the climatic conditions of the forest-steppe zone of central Russia. The species with the earliest beginning of the growing season (the third decade of March) were distinguished. There were Mahonia pinnata, M. aquifolia, Betula lenta and B. lutea. On the basis of phenological calendars, phenological spectrums have been constructed. These consist of three lines (the development of leaves, shoots, flowers and fruits) with the corresponding color symbols. It has been revealed that phenospectrums vary depending on the conditions of the year. As a result, the database of 20 species and forms of North American woody plants was formed in the form of phenological spectrums against the background of registration of weather conditions in the forest-steppe zone of Russia. The database includes three options for the possible dynamics of the seasonal development of introduced North American plants. The created database allows observing, comparing, evaluating and forecasting changes in the seasonal rhythm of the studied species of introduced North American plants.

Relevance. Leek (Allium porrum L.) has been known as a cultivated plant since ancient times. It plays an important role in human nutrition. To increase the interest of the population, increase demand and consumption, as well as widespread and popularize this culture, it is urgent to create new promising varieties of leeks that meet modern requirements and have valuable economically useful traits. The creation of new highly productive varieties is associated with the search for sources of valuable biological and economic traits: productivity, early maturity, yield. The aim of the research was to study collection varieties of leeks, to identify the sources of the necessary valuable traits for their further use in breeding work. Materials and methods. The initial material was 73 samples of leeks of the European subspecies of various ecological and geographical origin from the collection of VIR. The studies were carried out at the collection site of the Krymsk EBS, VIR Branch (Krasnodar Territory, the city of Krymsk). Results. As a result of the study of phenological, biological, morphometric and economic characteristics, the foliage of the plant, the size of its and the false stem of the "leg", productivity and yield were determined. Formed groups of samples by ripeness and use. Comparative assessment of collection samples made it possible to identify the sources of productivity: the weight of the plant and the stem, its diameter and height, the yield of plants and the yield of marketable products. The isolated sources of valuable traits are recommended as a starting material for the selection of leeks.

Relevance. To create heterotic cucumber hybrids, it is important to have a high general and specific combining ability of the initial material, which makes it possible to select valuable genotypes at an early stage of selection. Material and methods. The research was carried out in 2018-2020. at the Research Institute of Vegetable, Melon Crops and Potatoes, located in the Tashkent region of Uzbekistan (SRIVMC&P). Studied 6 accessions of cucumber. As a result of diallelic crosses, 36 hybrid combinations were obtained (p2). Hybridological analysis was carried out according to the first Griffing's method, including forward and backcrossing and the use of parental forms (p2). To determine the combining ability, conventional methodologies were used (1,15). Genetic-statistical analyzes were carried out using the MS Excel application package. Results. Studies have established that according to the traits "the number of days from seed germination to the opening of female flowers" and "the number of days until the technical ripeness of fruits" in all studied cucumber accessions, the ratio (σ 2ĝi<σ 2si) is observed, where the dominant role in the inheritance of this trait also belongs to genes with dominant and epistatic effects. The trait “number of fruits per plant” is controlled by dominant and epistatic gene effects (σ 2ĝi<σ 2si) in almost all cucumber accessions, and in the accession A-6 - by additive gene effects (σ 2ĝi <σ 2si). The phenomenon (σ 2ĝi <σ 2si) was noted for the trait "average fruit weight", where the expression of the trait is controlled by the dominant and epistatic effects of genes (σ 2ĝi <σ 2si) in three studied cucumber accessions (C-25/1, A-6 and A-9), and in the other three accessions, additive gene effects (σ 2ĝi <σ 2si) are more important in inheritance. The trait "productivity of one plant" is controlled by the dominant and epistatic effects of genes (σ 2ĝi <σ 2si) in the three studied cucumber accessions, and in the other three accessions (C-25/1, A-6 and A-9), genes play a special role for the expression of the trait with additive effects. Promising hybrid combinations with the best performance for their use as a initial material for breeding have been revealed.

Relevance. The use of certain single or mixed cultures of lactic acid microorganisms and the mandatory control of the fermentation process of white cabbage are of great importance to ensure that the product is of stable quality without the need for any chemical preservatives or harsh processing conditions. Carbohydrates contained in raw materials play an important role in this process, since carbohydrates are the main source of maintaining the viability of lactic acid microorganisms. By adjusting the carbohydrate component of raw materials at different stages of fermentation, it is possible to maintain a high titer of microorganisms, while obtaining not only a high-quality product, but also giving it, along with prebiotic (a source of fiber) and probiotic properties. Materials and methods. The purpose of this research work was to ensure the direction of the biotechnological process in the direction of stabilization of the concentration of functional microflora (starting systems of lactic acid microorganisms), under the influence of introduced carbohydrate nutrients. In this work, we studied two fermentation systems of microorganisms that are fundamental microorganisms in the fermentation of cabbage, namely, systems consisting of a pre-fermentation culture of Leuconostoc mesenteroides and one of the cultures of lactobacilli: Lactobacillus plantarum or Lactobacillus brevis. The study used the usual microbiological method for determining the number of microorganisms by seeding in an agarized culture medium, as well as processing experimental data. Results. As a result, we found that the introduction of a carbohydrate Supplement allows us to stabilize the dynamics of changes in the concentration of the studied starting systems at the same initial level throughout the main stage of fermentation.