Studying the length of the hypocotyl of cucumber seedlings

Relevance. Study the selection material of cucumber on the basis of the hypocotyl length, as well as to assess the stability of this feature depending on the year of research and the timing of sowing.Material and methods. Studies were conducted on the selection samplesof the laboratory cucumber breeding and seed production of Cucurbitaceae of FSBSI Federal Scientific Vegetable Center in 2019 and 2020 in terms of seedling branches winter greenhouse type "Richelle". Cucumber seedlings were grown without artificial illumination. Measurement of the length of the subfamily knee was performed at the stages of expanded cotyledons and the formation of the first true leaf.Results. The length of the hypocotyl varied in the phase of expanded cotyledons – from 3 to 8 cm, in the phase of the first real leaf – from 6 to 18 cm. It was found that at the early stages of development, in the phase of expanded cotyledons, it is effective to reject plants with a hypocotyl length ≥5 cm. This will allow you to get rid of unwanted samples at the early stages of growing seedlings or to conduct selection within populations. The final assessment of the breeding material for lodging stability should be carried out in the phase of the first true leaf, since the most intensive growth of the hypocotyl was observed in the interphase period "expanded cotyledons – the first true leaf". During this period, it is possible to select non-lodging samples in a group that was characterized by an average hypocotyl (3.7-4.0 cm) for the expanded cotyledon phase. In breeding samples, depending on the year of research, the difference in the length of the hypocotyl in the phase of expanded cotyledons was 0.1-0.8 cm. All this indicates the stability of this feature and, accordingly, the possibility of selecting forms with the necessary parameters. A comparative study of cucumber seedlings of different sowing periods (1.5 months difference) revealed the samples most sensitive to low light. Promising samples were selected with a short hypocotyl in the phase of expanded cotyledons (< 5 cm), which are of interest for breeding for seedling resistance to lodging.