Intense light culture, the most impotent part of a regulated agroecosystem, makes it possible to produce high quality plant products all year round in any region of the world in close proximity to the consumer. It is most economically viable to use light culture for growing vegetables in the Far North, where there is an acute shortage of fresh vegetables and vitamins. Our studies of the range of different vegetable crops have shown that when using artificial lighting and low-volume cultivation technologies, many plant species and varieties have low productivity, low adaptability to the relevant conditions, and therefore unprofitable for mass production. To expand the range of vegetable products intended for cultivation in the light culture, it is necessary to do a massive screening of the varieties and hybrids of various crops available in the world assortment with the aim of selecting the best and also purposeful breeding of new forms and varieties maximally adapted to the appropriate cultivation technologies. The purpose of this work was to create new forms of small radish for light culture, having the necessary complex of economically valuable characters. The use of the previously developed methodology of predicting transgressions for economically valuable plant traits allowed us to obtain new promising forms of radish with using purposeful hybridization and subsequent stabilizing selection. Their characteristics are high productivity and early maturity (ripeness to harvesting for 21-25 days from seeding), the ability to produce marketable yield of roots in a small volume of root medium, resistance to bolting at higher temperatures. A number of the obtained forms also has a compact rosette of leaves and an almost glabrous leaf of the salad type. Marketable productivity of new forms of radish in intense light culture conditions reaches 5,5 kg/m2 (for hybrids F1) and 4 kg/m2 for stable lines, which is twice or more than the productivity of the parental cultivars and one and a half times more than the best in productivity cultivars that were tasted in light culture.

The strategy of creating new radish forms adapted for cultivation under artificial lighting was developed and implemented. It was based on the original methodology of obtaining transgressive forms of various cultures with a predictable complex of economically valuable properties. Plants were grown in controlled conditions, under incandescent lamps DNAZ-400 (12 hours photoperiod, irradiation of 40-60 W/m2 PAR), in a small volume of the root medium. At the first stage, the intraspecific diversity of radish (26 varieties of different origin) under artificial lighting has been studied. Differences between varieties were determined for the complex of selective-valuable characteristics (early maturity, productivity, morphological characteristics). The most productive varieties are revealed, as well as varieties donors of economically valuable properties that are realized under artificial lighting at a short day and high temperature. Parent pairs have been selected for the subsequent receipt of highly productive transgressive forms using the original breeding methodology. The evaluation of hybrids of the first and second generation showed the presence of heterosis on the mass of the root up to 230% in various combinations of hybridization and revealed promising transgressive forms.

Supply of the domestic fresh vegetables commodity to the population of Northern regions of Russia is one of the most priority tasks of the national economy. Lack of the local, high-quality and adopted breeding material is highly problematic for breeding programs. Generation of the new, highly productive vegetable cultivars for the glass-covered ground, including light culture, will promote to expand significantly the volume of local production of vegetables in protected ground, especially in regions with a cold climate. One of the most prospective crops for protected ground is small radish, an early ripening crop with a valuable biochemical composition. А strategy for creation of the new, highly productive forms of small radish, beard predictable complex of economically valuable characters for growing in conditions of intensive light culture, has been developed in the Agrophysical Research Institute (SaintPetersburg). At the first stage, represent interspecific set of 26 small radish cultivars from different regions, was investigated in controlled conditions (artificial light, climate cell) to reveal a complex of economically valuable properties (early maturity, productivity, morphological traits). The plants were grown in original plant grooving light equipment (lamps DNaZ-400, photoperiod 12 hours, irradiation 15-20 klk), in a small volume of substrate (peat with mineral additives). It was observed that the small radish varieties have significant diversity in precocity, productivity, resistance to bolting, also they vary in a number of morphological features of roots and leaves. Bov, Estella, Rocco (Netherlands), Nobo Chind Criollo (Peru) were the most productive cultivars. They can produce yield of commercial roots during 30 days of vegetation up to 3.5 kg/m2. In addition, cultivars – genetic resources of economically valuable properties (compact rosette, glabrous leaf, resistance to bolting) were revealed for a breeding. Parent pairs for crossing were selected. It is planned to obtain offspring small radish forms with a complex of economically valuable properties, more productive than the parents. In all matched hybrid combinations, F1 hybrids were obtained. They have a degree of hybrid superiority in roots weight from 110 to 230% over the best of the parent form. They will become the ancestors of the original forms of small radish, intended for cultivation in conditions of intense light culture.

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.

Федеральное государственное бюджетное научное учреждение «Агрофизический научно-исследовательский институт», Санкт-Петербург, Россия, sinad@inbox.ru Аннотация. В условиях регулируемой агроэкосистемы проведены исследования влияния водной вытяжки из сухого листа стевии (Stevia rebaudiana Bertoni) на всхожесть семян, рост проростков и продуктивность растений салата и огурца. Выявлена стимуляция роста проростков при обработке семян исходной вытяжкой без ее разведения (концентрация основных стевиолгликозидов -1-1,2 мМ). Трехкратная некорневая обработка салата и огурца вытяжкой с концентрацией стевиолгликозидов 20-25 мкМ повышала биомассу обеих культур на 29-35%. Данный эффект объясняется наличием у стевиолгликозидов гиббереллиноподобной активности, что позволяет нам рекомендовать вытяжку из стевии в качестве эффективного и экологически безопасного стимулятора роста растений.Ключевые слова: стевия, водная вытяжка из листьев, гиббереллиноподобная активность, рост растений, стимуляция Abstract. The purpose of this experiment was to study of the effect of water extract from dry stevia leaves (Stevia rebaudiana Bertoni) on the seeds germination and on the growth and netproductivity of lettuce and cucumber. The experiments were carried out under controlled condition (artificial light). The growth stimulation of seedlings was revealed during the seeds treatment with the initial extract without dilution (at the concentration of basic steviol glycosides -SG -in the extract 1-1.2 mM). Three foliar treatment of lettuce and cucumber with extracts from Stevia with a concentration of 20-25 μM SG increased the net-productivity of both crops by 29-35%. This effect is apparently due to the presence of Gibberellin-like activity in SG. Water extract from stevia leaves can be recommended as an effective and environmentally safe plant growth stimulator.