Bioecological characteristics and decorative representatives of the genus Robinia L. according to phonological data

Abstract

The object of research was the species, varieties and forms of the genus Robinia: R. viscosa var. hartwegii (Koehne) Ashe; R. neomexicana var. rusbyi; R. neomexicana f. pale pink; R. neomexicana f. pale purple; R. pseudoacacia L.; R. pseudoacacia f. pyramidalis (Pepin) Rehd.; R. pseudoacacia f. umbraculifera (DC) Rehd. and R. pseudoacacia x R. neomexicana, growing in the dendrological collections of the Federal Research Center of Agroecology, Russian Academy of Sciences. Most of the phenological phases of representatives of the genus Robinia occur at the optimal time for the seasonal development of flowering woody plants. This genus belongs to the group of late beginners and late terminators of the growing season. The indicator of phenological atypicality (+1 - 0) is in the lower half of the normal area, and for some species and forms (R. viscosa var. Hartwegii, R. pseudoacacia f. Pyramidalis, R. pseudoacacia f. Umbraculifera) at the edge of the normal area (+ 0.8 - +1). The research area for these introduced species is the northern border of the wide range of culture and their further promotion to regions with a more severe climate is possible only in experimental plantations or as an additional assortment. The most winter-hardy were the varieties, forms and hybrids of R. neomexicana with a phenological atypicality index from +0.3 to +0.35. We can recommend these plants for widespread use even in the northern regions of the Volgograd region due to their potential winter hardiness. The study of seasonal rhythms revealed the periods of maximum decorativeness of representatives of the generic complex Robinia, and a comparative characteristic in terms of the beginning and end of flowering. The authors found that R. viscosa var hartwegii has the longest flowering period.