MORPHOGENESIS OF IRIS HYBRIDA SHOOT RENEWAL

Iris hybrida (Iridaceae) cultivars from the class of bearded irises are distinguished by decorative and biological features of renewal shoots’ development when cultivated in specific soil and climatic conditions. I. hybrida model cultivar ‘Siegfried’ shows the morphogenesis of the renewal shoot with organogenesis elements, as well as growth and development features in the south of Novosibirsk region of Western Siberia for 2019–2023. It is noted that the renewal shoot of ‘Siegfried’ cultivar is in an underground rudimentary state in the form of a bud for 19-20 months and is for 4–5 months above ground (vegetation, flowering, fruiting); its growth apex gradually passes from I to XII organogenesis stages and develops according to the dicyclic type. The formation of generative organs in a monocapical shoot occurs in spring when plants regrow. Within 20–21 days, the monocarpic shoot of ‘Siegfried’ cultivar develops rudimentary generative organs and the growth apex passes from II to VII stages of organogenesis. The above-ground development of monocarpic shoot is characterized by the VIII–XII stages of organogenesis from the beginning of budding to fruiting and the formation of mature seeds (June – August). Renewal shoots for the next vegetation year (vegetative and generative) are laid in the summer and winter in a vegetative state at II stage of organogenesis. The first stage of organogenesis is distinguished by the formation of initial cells in a bud and passes quickly. Morphoanalysis of the annual underground shoot of I. hybrida cultivar ‘Siegfried’ (late July) showed that the buds of three formations are laid on it: dormant, lateral and apical (terminal); thus in the underground part of the plant, three year-old shoots’ generations have been formed in different years. A pattern was noted in the annual cyclic sequence of bud set. Alternation of underground shoot growing from orthotropic to plagiotropic direction leads to formation of a loose clone, with vegetative-mobile specialized disintegration. I. hybrida cultivars are characterized by loose-root above-ground vegetative-mobile biomorph, which ensures the formation of new metamers at the shoot according to the sympodial growth type. During the pre-generative period of ontogenesis, the shoot grows monopodially. The development of renewal shoots in nineteen bearded cultivars grown in the forest-steppe zone of Western Siberia is similar to the passage of the morphogenesis stages of the monocarpic shoot on ‘Siegfried’ cultivar, which is important for the selection, preservation of the gene pool, reproduction, practical use and breeding of varietal diversity of I. hybrida.