Seed Propagation of Spiraea L. Species in the Botanical Garden of the Ural Federal University

Abstract

Spireas (Spiraea L.) are widely used in landscaping, while the number of spirea species and cultivars used in Yekaterinburg landscaping is small. Information concerning seed germination will enable the development of effective methods of plant propagation for various purposes, including landscaping. Spirea seeds collected in the botanical garden of the Ural Federal University served as research material. Seed germination was monitored from 2015 to 2018. The study of daily dynamics of seed germination showed that the most active sprouting seeds were the following: S. salicifolia L. and S. humilis Pojark. Seeds of these spireas germinated on the 2nd day after sowing. Seeds of other species began to germinate only on the 3rd day after sowing. The following seeds were highly germinative: S. salicifolia (89.5–97.8 %), taxonomically related to the previous species S. humilis (77.0–96.3 %), and a polymorphic species with a wide range in Eurasia S. chamaedryfolia (71.8–92.5 %). Seed germination of other spireas varied from year to year. This may be related to the lower adaptive potential of these species in the Middle Urals. Perhaps vegetative propagation will be economically useful for these species. The field germination was lower than laboratory germination (from 12.5 to 24.5 % for different species). At the same time, all spireas, except for Spiraea ussuriensis, are capable of regenerating naturally to some extent in the Botanical Garden. Excessive moistening and low temperatures during the growing season and high average winter temperatures had a negative effect on growth and development of spireas and, consequently, on the quality of seeds produced by them. The depth of snow cover in March has a direct correlation with seed quality, as it provides sufficient moisture in the soil at the beginning of the growing season.