Abstract:

Pinus sibirica Du Tour is one of the primary forest species in Russia. This work aimed to determine the variation in growth and elementary structure of shoots in latitudinal and longitudinal ecotypes using a common garden experiment, with emphasis on the ratio between shoot metamere types. The study was conducted in the southern taiga ecoregion in the south-east of the West Siberian Plain in Russia. We investigated 23-year-old grafts from eight Pinus sibirica ecotypes grown under uniform conditions. Ten-year-old branches were selected from the crowns of the grafted trees, and a retrospective analysis of shoot structure was conducted. The length and metameric composition of the branches varied significantly between different latitudinal and longitudinal ecotypes. Growth rates in the southern and eastern ecotypes were higher than those in the northern and western ecotypes. However, the proportions of auxiblasts did not differ between ecotypes. The southern ecotype showed the largest shoot sterile zone and the longest internodes and needles. The eastern ecotype showed the largest number of brachyblasts and relatively long internodes. Thus, the proportions of metameres involved in shoot elongation and internode length depend on the geographic origin of ecotypes when growing their vegetative progeny ex situ.

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