Evaluation of sainfoin (Onobrychis) in the source material nursery according to new selection criteria at the initial stages of organogenesis

Topicality. The implementation of new selection criteria will solve the problem of forming the sainfoin resistance to extreme hydrothermal conditions and insufficient moisture. Sainfoin adult plants have a high level of drought resistance, unlike its seedlings, which are sensitive to the air and soil moisture deficit. Therefore, the ability of seedlings to adapt to unfavorable moisture conditions has a positive effect on the further development of plants and the formation of their productivity elements. Purpose. To evaluate the principles of new selection criteria for sainfoin biotypes in the breeding process at the initial stages of organogenesis. Materials and methods. The laying of the nursery of the initial material was carried out using new elements of the technology of growing sainfoin, namely summer sowing. Seeds of samples obtained by positive selection from breeding, seed crops, collections of other scientific institutions and local wild populations of sainfoin were sown. The new criteria for selecting sainfoin biotypes are based on an assessment of the intensity of root system development and the calculation of the coefficient of negative drought effect. General scientific research methods are as follows: field, laboratory, measuring-weight, calculation-comparative, mathematical statistics. Results. In the source material nursery of the first year of life, 113 families (45.7 % of the total) formed a root system with a volume of more than 6.5 cm³ within 2.5 months after sowing. Only 77 families (31.2 % of the total number) had a drought impact coefficient of 0.46 or less, i.e., they are suitable for breeding highly productive populations in arid climatic conditions. Sowing seeds of families selected according to the new criteria ensured that number of families with a strong root system (more than 6.5 cm³) increased from 42.2 % to 57.2 % in the next generation, increased plant survival during the first year of life from 63.2 % to 87.2–95.0 %, in winter – from 83.3 % to 90.4–94.8 %, and resistance to fungal diseases from 81 % to 90–95 %. In the nursery of the source material, the share of families with the highest number of shoots per plant (> 27 pcs) and height (> 20 cm) was 27.4 % and 26.6 %, respectively, and was equal to the number of families with a root volume of more than 7.5 cm³ – 27.4 %. Conclusions. According to the results of determining the root volume of sainfoin plants and calculating the coefficient of negative effect of drought, the most productive breeding samples can be selected in the first years of life when using summer sowing with freshly harvested seeds. The selection of breeding material based on new criteria made it possible to identify families with high adaptive potential at the initial stages of plant development in arid conditions of the eastern part of the Northern Steppe of Ukraine. Key words: breeding, sainfoin, root volume of plant, coefficient of negative drought impact, condition of plants