Tree-Ring Structure of the Pinus sibirica and Pinus cembra Grafts as a Reflection of the Interaction of Scion and Rootstock

Abstract

The analysis of the anatomical characteristics of tree rings of P. sylvestris L. rootstocks and scions of P. sibirica Du Tour (Emelianovo and Surgut provenances) and P. cembra L. (Karpat provenance) has been carried out for 10 years of their joint growth. The number of tracheids, their radial diameter and the cell wall thickness for the P. sibirica scions increases relative to control trees (with the exception of the cell wall thickness for Surgut scions). At the same time, in the annual rings of the P. sylvestris rootstocks these characteristics as well as the number of tracheids decrease relative to the control trees. An exception is the Scots pine, which is the rootstock for Surgut provenance scion, for which the radial tracheid diameter of the transition zone increases. The seasonal dynamics of the radial tracheid diameter and the cell wall thickness of the grafted trees retains the species features typical for the ungrafted trees, suggesting the stability of the genetic program of xylem differentiation. The adaptation of scions to the climatic conditions of their place of origin does not affect the anatomical structure of the tree rings of the rootstocks during the years in which the conditions are close to the climate of the region of origin of the scions.