Determination of the criteria for distinctness, uniformity and stability of new varieties of romaine lettuce Lactuca sativa var. longifolia L.

Purpose. To reveal the peculiarities of determining the criteria of distinctness, uniformity and stability of new varieties of romaine lettuce by identifying the phenotype of Lactuca sativa var. longifolia L. in accordance with international requirements and establish the morphological code formula of the official description, according to which the state registration of the variety was carried out. Methods . Field identification method – morphological description of qualitative (QL), quantitative (QN) and pseudo-qualitative (PQ) characters, laboratory, statistical. Experimental stu­dies were performed during 2015–2017. Field experiments were conducted in the vegetable crop rotation of the Yakimovska variety research station in the Zaporizhzha region under drip irrigation conditions in accordance with the Research Methodology in Vegetable Growing and Melon Growing and the Lactuca sativa L. seed lettuce varieties for distinctness, uniformity and stability. Results. The article presents the results of field and laboratory studies on the identification of varieties of romaine lettuce Lactuca sativa var. longifolia L. The varieties of this type form a productive organ head with elongated solid leaves and a distinct central vein, the predominant form in cross section is elliptical, the head height is predominantly more than 1.5 times its diameter. Insofar as the vegetative and generative organs of romen lettuce plants varieties were the subject of morphological description of identification signs with the subsequent establishment of a manifestation code. A comprehensive assessment of new varieties of romain lettuce according to morphobiological and economically valuable characteristics is substantiated. For the grouping of varie­ties, characteristics that do not vary or slightly vary within the variety were used: seed color, anthocyanin leaf color, the start time for the formation of flowering shoots, resistance to downy mildew ( Bremia lactucae ): Isolate – Bl:16. These signs are used alone or in combination with others. Conclusions . It was revealed that new varieties of romaine lettuce differed in their morphological characteristics by one or more identifying signs from the well-known varieties ‘Sovskyi’ and ‘Skarb’, which for the period of research represented a collection of varieties of var . longifolia L. New varieties of romaine lettuce ‘Aivona, ‘Batsio, ‘Viktorinus’, ‘Halateia’, ‘Kvintus’, ‘Klaudius’, ‘Korbana’, ‘Maksymus’, ‘Ovired’, ‘Oktavius’, ‘Rafael’ were uniform and stable, as evidenced by the morphological code formulas that made up the official description of the variety, according to which the state regi­stration of the variety was carried out and it was included in the Register of Plant Varieties of Ukraine.