The origin of Herbaceous hybrid Group peony cultivars of the M. M. Gryshko National Botanical Garden of NAS of Ukraine collection and the prospects for their use

Purpose. To analyze the origin of the Herbaceous Hybrid Group peony cultivar collection of the M. M. Gryshko National Botanical Garden (NBG) National Academy of Sciences of Ukraine (NAS) and to determine the prospects for their use in breeeding work and decorative horticulture. Methods. The object of research was peonies of the Herbaceous Hybrid Gp of the NBG peony collection. The plants are grown on sunny open experimental and exposition plots of the NBG. Cultivars studies and phenological observations of plants were carried out during 2012–2022. Results. Varietal diversity of Herbaceous Hybrid Gp peonies of the NBG collection was analyzed by origin. The analysis showed that 122 varieties were created by US breeders, of which the Saunders breeding is represented by the largest number of varieties in the collection. 38 varieties are of Ukrainian breeding and created in the NBG. The analysis of hybrids obtained by distant crosses made it possible to identify combinations that give fertile offspring and to create promising double and triple hybrids. For decorative horticulture, 165 varieties of world and domestic breeding are recommended. They were grouped into four groups by flower color and two groups by the beginning of flowering. Plants of the early group start flowering before May 22 (± 4 days). The flowering of the late group of varieties occurs at the beginning of the flowering of the variety ‘Red Charm’ (May 22 ± 4 days) and later. Conclusions. For more than 50 years of introductory work with peony Herbaceous Hybrid Gp, 133 varieties of world breeding were tested at NBG. The main number of varieties was included in the collection in the first years of the 21st century. A comparative study of new varieties showed that most of them are sterile. Varieties ‘Dreamtime’, ‘Greenland’, ‘Quitzin’, ‘Lavender Whisper’, ‘Lemon Chiffon’, ‘Pastelegance’, ‘Pastelorama’, ‘Salmon Dream’, ‘Sunny Boy’, ‘Sunny Girl’, ‘Sunny Day’, ‘The Mackinac Grand’, ‘Vanilla Schnapps’, ‘Triphena Parkin’, ‘Pink Vanguard’, ‘Lavender Whisper’, were fertile and can be successfully used in the hybridization process. It was revealed that the source of early flowering of varieties created in the NBG was introduced wild species of herbaceous peonies: P. peregrina, P. wittmanniana, P. arietina. Peonies with double or semi-double flowers can be obtained by using P. officinalis ‘Rubra Plena’ with double flowers as a maternal component, and P. lactiflora varieties (‘President Taft’, ‘La Pionce’, ‘Lord Kitchener’, ‘Adolphe Roussean’, ‘M-lle Janne Riviere’) as paternal one also with terry flower