Scientific relevance. Currently, in the protected ground, the main areas are occupied by parthenocarpic hybrids of cucumber of foreign origin. Therefore, the selection of domestic cucumber hybrids of the parthenocarpic type is very relevant.Material and conditions. The experience was laid in 2018-2022 in the Odintsovo district of the Moscow region in the conditions of a spring film ground greenhouse of the "Block" type on the basis of the head institution of the FSBSI FSVC. Agrotechnics of cultivation is generally accepted for the conditions of spring film greenhouses. In breeding nurseries where there were no bees, the degree of parthenocarpy was determined as the ratio of the fruit set to the number of female flowers formed on the plant, as a percentage. The records were carried out from the 5th to the 20th node inclusive, only on plants of the female type of flowering. On the basis of the laboratory of breeding and seed production of pumpkin crops, 27 collectible and more than 50 breeding samples of parthenocarpic cucumber were studied.Results. During three years of research, 7 hybrids of cucumber of the parthenocarpic type of foreign breeding were selected based on the sum of economically useful traits.These hybrids were distinguished by a high degree of parthenocarpy. With their participation, as a result of multiple selections and self-pollination, more than 50 breeding lines were created. Analysis of the obtained material showed that the degree of manifestation of parthenocarpy on the plant (the arithmetic mean between the indicators of parthenocarpy on the main and lateral shoots) in the best half of the samples in 2021 was in the range of 30-50%, whereas in 2022 it already reached 50-70%. The parthenocarpy severity coefficient above 70% was noted only in 2022 in 4% of samples. About half of the samples showed a fairly low parthenocarpy: in 2021 no more than 30%, and in 2022 no more than 50%. Most of them were rejected. The parthenocarpy of the best breeding samples in 2022, compared with 2021, increased by an average of 17.7%. Breeding lines obtained even from the same collection sample often differed greatly, sometimes by 4 times, in the degree of parthenocarpy. The families of the most stable parthenocarpy samples had differences on this basis in 2021 only 3-6%, and in 2022 – 10-11%. Families with the greatest severity of this trait were selected annually. It can be concluded that the degree of parthenocarpy in cucumber strongly depends on both the genotype of the sample and the growing conditions. 3 breeding lines were selected, characterized by high indicators of the degree of manifestation of parthenocarpy in 2021 (61.5-70.5%) and the stability of the manifestation of this trait by families and years.

The purpose of the study. The aim of the study was to determine the effect of heterosis in short-fruited parthenocarpic F1 cucumber hybrids by the main economically valuable characteristics, when grown using low-volume technology in industrial greenhouses of the Moscow region.Materials and methods. The object of the study is short-fruited parthenocarpic reciprocal hybrids of cucumber Druzhny (F1 I73514 x I74011), F1 I74011 x I73514 and their parent inbred lines I73514 and I74011 of selection by N.N. Timofeev Breeding Station LLC. F1 SV4097CV of foreign selection of Semenis company (Netherlands) was used as a control. The study was conducted in 2020-2021 in industrial greenhouses of the "V. I. Edelstein Vegetable Experimental Station" of the K.A. Timiryazev Russian State Agrarian University-Moscow Agricultural Academy in Moscow on low-volume hydroponics in peat bags. Parental lines and hybrid combinations were evaluated by earliness, early yield, yield, number of fruits per plant, average fruit weight and marketability.Results. According to the results of the study, F1 Druzhny (F1 I73514 x I74011) and the reverse hybrid I73514 x I74011 demonstrated high positive effects of heterosis in yield (MPH=19.4...22%; HPH=13.4...15.9%; CH=9.6...12%) and the number of fruits per plant (MPH=22.5...26.4%; HPH=12.5...15.8%; CH=11.7...15%). Negative indicators of the heterosis effect were noted for earliness from germination to flowering (MPH=-3.4...-1.1%; HPH=-6.5...-4.4%; CH=-4.4...-2.2%) and average fruit weight (MPH=-2.2...-1.3%; HPH=-5.3...-4.3%; CH=-3.4...-2.4%). The value of the degree of dominance indicates the presence of positive overdominance in the inheritance of such traits as yield (hp=2.7...3.2), the number of fruits from the plant (hp=1.5...1.9) and marketability (hp=1.6...2.3). Negative overdomination was observed in earliness from germination to flowering (hp= -2...-1.3) and average fruit weight (hp=-1.7...-1.2). According to the signs of earliness from germination to fruiting (hp =0) and early yield (hp=-0.1...0.5), intermediate inheritance was revealed. The Druzhny hybrid significantly exceeded the control hybrid SV4097CV in early yield, yield and number of fruits from the plant, and the reverse hybrid F1 I74011 x I73514 was at the control level, which indicates the prospects of growing these hybrids in the conditions of spring-summer turnover on low-volume hydroponics.