The graceful fir (Abies gracilis Kom., Pinaceae) in Saint-Petersburg and Leningrad region: history of arboriculture, biological peculiarities and methods of reproduction

The article is devoted to the history of arboriculture, biological features and methods of reproduction of graciful fir (Abies gracilis Kom.). This plant has been cultivated in St. Petersburg since 1986 and in Leningrad Region - since 2009. The best specimens have reached 7,1 m high under the age 33 years. The first fruiting was observed in 2007 under the age 17 years, which is much earlier than in natural habitats in Kamchatka. Originally the fruiting was episodic and not every year; it has become regular since 2016, and was very heavy in 2019. Germination ability is 0,12-0,29 %, the seed reproductions of second generation was obtained in 2015. The seeds are characterized by high parthenocarpy. The high level of empty seeds, the poor quality of endosperm and the lack of embryo are discovered on x-ray analysis. On vegetative propagations by cuttings the ratio of rooted cuttings reach up to 67,5 %. The rooting percentage increases with the use of original multicomponent root formation stimulants. The vitality of grafting by applying the pith on cambium with stock of Abies balsamea (L.) Mill. was reached to 81,8 %. So, the propagation is possible by all three methods: by seeds, cuttings and grafting. The problems remain: the low germination ability of seeds and the slow growth and development of young plants.