Relevance. Contarinia nasturtii Keiffer is one of the most dangerous insect pests of Brassicaceae plants dramatically affecting plant yield and seed productivity.Material and Methods. The effect of single foliar application of sodium selenate, ionic form of silicon (Siliplant fertilizer) and garlic extract on the efficiency of Raphanus sativus lobo defense against Contarinia nasturtii infestation was evaluated in condition of greenhouse. Concentrations of the applied reagents were: sodium selenate 26.4 mM; Siliplant – 1 ml/l; garlic extract – 8 g/l. Seed productivity and C. nasturtii infestation levels under Se, Si and garlic extract administration under infestation were determined along with the analysis of plant antioxidant status and sugar content.Results. Foliar application of Siliplant singular or in combination with Se provided the highest seed productivity and mass of 1000 seeds. Plants treated with Si, garlic extract and Si+Se demonstrated lack of C. nasturtii infestation only a week after the preparation supply. Contrary, selenate provided less pronounced defense. Among biochemical parameters tested the values of the total dissolved solids were the highest in plants treated with Se and Se+Si. Changes in the intensity of plant defense due to garlic, Se and Si supply were reflected in the increase of the total phenolic content compared to the values typical for control plants and in a significant accumulation increase of disaccharides, participating in tissue recovery after herbivory attack. Silicon application also provided an increase of selenium accumulation by lobo leaves.

Relevance. Cucumber in the Russian Federation in protected ground in terms of growing areas and production volume is the first, its share in the total production of greenhouse products in recent years accounts for about 50-55%. Scientific research confirms the positive effect of silicon-containing agrochemicals on the intensity of metabolic processes in the plant body, which is manifested in increasing the yield of commercial products, resistance to adverse environmental factors, and the realization of the biological potential of crops. Methods. The aim of the research is to evaluate the effect of silicon – containing fertilizers on the productivity of Cyborg F1 cucumber in low-volume cultivation technology. The research was conducted in the winter-spring period of 2020 in the conditions of a winter glazed greenhouse of the greenhouse complex of the Stavropol state agrarian university. The objects of research were cucumber Cyborg F1, fertilizers Kelik Potassium Silicon, Siliplant, Forris, Bio Silicium. Fertilizers were applied to foliar top dressing three times during the cucumber growing season. All microclimate conditions in the greenhouse were regulated automatically using the Sercom climate program. Mineral wool was used as a substrate. Results. Fertilizing with silicon – containing fertilizers increased the degree of assimilation of nutrients by plants of cucumber Cyborg F1: the nitrogen content in the drainage solution decreased by 6-26 mg/l, phosphorus – by 4-8 mg/l, and potassium-by 18-34 mg/l. The use of silicon-containing fertilizers contributed to an increase in the area of cucumber leaves compared to the control by 1.6-3.1%, the yield of standard products-by 3.7-8.1%, yield-by 0.9-2.5 kg/m2, and a decrease in the degree of ovary death – by 2.0-3.5%. When using silicon-containing fertilizers, the quality of cucumber products improved. Thus, in the conditions of the sixth light zone, to increase the yield of Cyborg F1 cucumber in low-volume cultivation technology, it is recommended to use silicon-containing fertilizers Siliplant and Forris, which provides an increase relative to the control of 7.4 and 9.2%, respectively.

Selenium (Se) and iodine (I) are essential elements for humans, and their deficiency is widespread throughout the world. In order to obtain a functional nutritional product with an increased content of these trace elements in the vegetative experiment, foliar biofortification of two chervil varieties with selenium (sodium selenate 10 mg/l) and iodine (potassium iodide 100 mg/l) was carried out without and against the background of the use of silicon-containing fertilizers Siliplant (3 ml/l). The combined and separate application of selenate, iodide and Siliplant increased plants’ biomass. Siliplant utilization increased the accumulation of iodine by 1.7-1.9 times, and selenium supply – by 2.2-3.1 times. A significant increase in ascorbic acid content was provided by the combined supplementation of iodine and selenium (1.25-1.27 times), iodine and silicon (1.46-1.87 times) and joint application of selenium, iodine, and silicon (1.31-1.73 times), while an increase in total antioxidant activity (1.3-1.4 times) was observed for (Se+I) and (Se+I+Si) treatments. High varietal differences in the responsiveness of plants to the selected treatments were manifested, particularly an increase of polyphenols accumulation under separate and joint treatments of chervil with iodine and selenium by 1.26 times in the cultivar 21-20, and the absence of a significant effect in the cultivar 24-20. Taking into account the adequate consumption levels (ACL) of iodine and selenium, 50 g of the resulting functional product can provide up to 79% of iodine ACL and up to 40% in selenium ACL.