There is limited information about the critical period for weed control (CPWC) in oilseed radish (Raphanus sativus L. var. oleiformis Pers.) This significantly limits the effectiveness of the applied technologies in its cultivation. The article focuses on the results of a long-term study (2013 to 2018) of the peculiarities of weed formation in oilseed radish agrophytocoenosis using different sowing technological models according to seeding rate and row spacing parameters. The study included the peculiarities of the species and generic composition of weeds and the basic attributes of the formation of species-specific amounts. The summed dominance ratio (SDR) was heterogeneous and co-oscillatory in the weed structure for both the formation of the number of individual species and their height dominance, which depended on the phenological stage of growth and crop development. In the general spectrum, the prevailing weed forms were identified with the highest potential for oilseed radish plants with an SDR greater than 1.0, which belong to groups I and VI according to environmental plasticity and stability, given the different conditions of the study period for both hydrothermal conditions and year index. In conclusion, a critical period for weed control (CPWC) in oilseed radish agrocoenosis was defined as a 5% reduction in crops ranging from 5 to 45 d after sprouting (DAS) for row sowing and a seeding rate of 4.0 million similar seeds ha-1 and 6 to 60 DAS for a variant of wide row sowing at a seeding rate of 0.5 million similar seeds ha-1 .

The growing interest in alternative fuels based on plant oils has led to the search for new plant species. Given this, during 2015-2020, oil from 12 varieties of oilseed radish was studied using standard research protocols. The average content of the dominant fatty acids in the oils studied was: [cis-9] oleic (C 18:1) 33.95% (Cv = 14.2%), [cis-9,12] linoleic (C 18:2) 16.20% (Cv = 20.8%), [cis-13] erucic (C 22:1) 15.18% (Cv = 17.9%), [cis-9, 12, 15] α-linolenic (C 18:3) 13.33% (Cv = 18.5%) and palmitic (C 16:0) 5.42% (Cv = 18.5%), with a monounsaturated fatty acid content of 59.69% and a ratio of polyunsaturated/monounsaturated fatty acids of 0.508. The studied varieties were ranked in the order of increasing suitability as a component of biofuels: 'Zhuravka' < 'Raiduha' < 'Lybid' < 'Olga' < 'Iveya' < 'Ramonta' < 'Alpha' < 'Tambovchanka' < 'Fakel' < 'Snizhana' < 'Sabina' < 'Nika'. The technological suitability of oil from the 'Zhuravka' variety was confirmed based on analysis of its physicochemical parameters when subjected to polymerization (at 280 °C) and oxypolymerization (at 120 and 150 °C). Under these conditions the basic parameters of the oil varied within the technological limits that determine its suitability for thermodynamic combustion processes in systems with controlled pressure and temperature.

The article summarizes the importance of studying alelopathic interactions between plants, taking into consideration the ecologization and biologization of the weed control system in agrocenoses of agricultural crops. The urgency in solving this issue with the use of intermediate forage and green manure crops and, in particular, oil radish, has been emphasized. The paper presents the results of studying the efficiency of using oil radish as a phyto-mediator in crop rotation to suppress and control various biological weed species by determining the germination of seeds of the oil-bearing radish variety Zhuravka by two research methods – germination on filter paper when moistened with water extracts of various types of weeds and germination on soil subtrate when moistened with the same extracts in a mode close to real soil conditions for germination of oil radish seeds. The used wide range of concentration of aqueous extracts from 0.25% to 16.0% with equal interval step allowed us to confirm the significantly different sensitivity of oil radish at the germination stage both in the version of traditional germination on filter paper and in germination on a soil substrate. At the same time, it was noted that oil radish has a sensitive reaction to water extracts of the studied 20 species of weed plants in the concentration range from 0.25% to 16% with the boundary value of the formation of the minimum level of laboratory seed germination at a concentration of 4.0%. The maximum effect of the impact on the indicators of laboratory germination of oil radish seeds, taking into consideration the minimum permissible level of decrease in the value of germination of seeds, was noted in the concentration range of aqueous extracts of 1.0-4.0%. Gradual growth of allelopathic pressure on germination of oil radish seeds on filter paper can be placed in such an increasing row: Field mustard (PA) - Artemisia ragweed (PA) - Tenacious ragweed (PA) - Wild radish (PA) - Actinoid thistle (PA) - Lettuce wild (PA) - Wheatgrass (PA) - Field cabbage (VA) - Common shchiritsa (VA) - Rough highlander (VA) - Field bindweed (VA) - Kulbuba officinalis (VA) - Field horsetail (VA) - Golinsoga small-flowered ( VA) - Common herringbone (VA) - Gray bristle grass (VA) - Canadian malignant (VA) - Yellow thistle (VA) - Pink thistle (VA) - White Mary (VA).

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In the article the results of studying of features of role of trace elements in the formation of the quality indicators of seeds of oilseed radish in two varieties are reflected. Systematized the views of various researchers on the processes of formation of oil content in cruciferous crops in general and radish oilseed in particular, given the current strategy of fertilizer oilseed crops of the family Cruciferae. Studied feature of the stages of the implementation and effectiveness of mono-component micronutrients in the form of easily soluble and readily available substances. The studied set of microelements included the recommended list of physiologically important components of modern microfertilizer formats and their chemical composition in order to optimally analyze the effectiveness of application for their single application in two key phases of oilseed radish – the phenological phase of stalking and the phenological phase of flowering. The use of each of micronutrients was effective and substantial compared to the oil content of seeds of both cultivars of oilseed radish given the level of oil content in seeds in control variant. The magnitude of the variation in the oil index was estimated taking into account the differences in the nature of the hydrothermal regimes of the research period. This allowed to determine the degree of genotypic nature of the formation of the oil content of seeds in oilseed radish and the possibility and effectiveness of selection of appropriate genotypes with the prospect of obtaining oil in the technical direction of use. Also assessed the role of individual micronutrients in the magnitude of the volatility of oil content in seeds of oilseed radish. Determined that the increase of oil content in seeds of oilseed radish the addition of various trace elements in the range of 0.3-1.4% from the close dynamic the resulting effective action on the formation of this indicator in the form of Co>Zn>Cu>B>Mn>Mo. It is proved that the efficacy of these minerals increases with introducing them into the flowering stage, which is a critical period regarding the implementation of the reproductive potential of the plants of oilseed radish and the formation of appropriate indicators of the quality of its seeds. The recommendations for further research in the field of optimization of fertilizer radish seeds and micronutrients were formulated. Key words: oilseed radish, fertilizer, microelements, seed quality, oil content, variety.

The article highlights the results of studying critical periods in the phenological development of oilseed radish varieties based on the use of basic indicators of the chlorophyll fluorescence induction curve (initial fluorescence (F0), plateau zone fluorescence (Fpl), maximum fluorescence (Fm), and stationary fluorescence (Fst). This complex was applied to oilseed radish plants of three varieties – ‘Rayduga’, ‘Zhuravka’ and ‘Lybid’ with the presentation of results for the variety ‘Zhuravka’ due to the similarity of the obtained data. phases of growth and development of oilseed radish: cotyledon phase, budding phase, flowering phase, green pod phase and yellow-green pod phase. Based on the use of a single-beam porous fluorimeter ‘Floratest’, developed by the Research and Engineering Center of Microelectronics of the Institute of Cybernetics named after V.M. Glushkova (Ukraine) formed curves of chlorophyll fluorescence induction (CFI) in the mode of 90-second fixation of parameters for each phenological phase of oilseed radish plants.The system of graphical display of regularity of formation of basic indicators of CFI curve within the main phenological phases is analyzed and generalizations and conclusions concerning dynamics of course of photochemical physiological processes of photosystem II of plants are made. in the process of phenological stage changes and the corresponding processes of morphogenesis of oilseed radish plants. The dynamics of exogenous and endogenous factors on the formation of indicators of assimilative activity of oilseed radish plant photosystems is analyzed on the basis of analysis of position and changes in time of main points of CFI schedule and substantiated obtained indicators with predicted physiological state of plants and possible assimilation activity. The values of baseline and indication indicators of CFI curve are compared to the main phenological phase of flowering, which is defined as the baseline in ensuring the realization of the productive potential of oilseed radish plants.

The article reflects the results of studying the peculiarities of the study of drought and heat resistance of three zoned varieties of oil radish, based on widely tested methods applied to a number of other agricultural crops. The viewpoints of many researchers on the processes of forming the temperature stress adaptations of plants have been systematised, taking into consideration the mechanism of drought and heat resistance and its role in providing the development of adaptive elements of the technology for growing cruciferous crops and climatic changes in the growing season in the area of economic distribution of oilseed radish. The peculiarities of the application of two laboratory techniques simultaneously have been studied. One of the methods is based on stress reactions of seeds with an assessment of the level of its germination after preliminary long-term heating of the wetted seeds by gradually increasing high temperatures. The second technique is based on the temperature reaction of the assimilation apparatus of plants to an environment with different temperatures in order to determine the degree of destructive effect of high temperatures on leaf structures with the subsequent determination of the degree of damage to the studied samples by staining the affected areas in the appropriate chemical environments. The application of this methodology has made it possible to determine that the threshold temperature value for forming the standard permissible levels of laboratory germination of seeds in the studied varieties of oil radish is in the range of 35-45 °C. The actual intensive decrease in laboratory germination for seeds with one-year biological age in the studied varieties of oil radish has been distinguished for the temperature regime of heating at 60 °C and higher with a zero level of laboratory germination at 80 °C. Considering the short heating period of pre-soaked seeds, oil radish plants are able to withstand a short-term increase in air temperature with sufficient soil moisture in the confidence range of 40-55 °C. Considering the decrease in laboratory germination for seeds of biological age 1-5 years already starting from the level of preliminary heating at a temperature of 30 °C – the optimum germination of oilseed radish varieties and the optimal growth and development of oilseed radish plants in conditions of sufficient soil moisture was most likely in the range of 20-25°C. Based on the results of the application of these methods in relation to drought and heat resistance, the studied varieties of oilseed radish can be placed in the following order of decreasing of the indicator ‘Raduga’-‘Zhuravka’-‘Lybid’. The prospects for further research in the field of optimizing drought and heat resistance diagnostics by laboratory methods have been formulated. Key words: oilseed radish, drought resistance, heat resistance, germination, temperature adaptation.