Articles
INFLUENCE OF ASSIMILATIVE APPARATUS ON BIRCH WOOD FORMATION
Article number
835_9
Pages
109 – 116
Language
English
Abstract
The Karelian birch (Betula pendula var. carelica) is widely known all over the world due to highly decorative patterned and wavy wood.
Our researches have shown, that biochemical inductor of the changes in the program of differentiation of cambial zone cells during the formation of structural anomalies of the trunk which are pertinent to Karelian birch is an increase of sucrose concentration in the phloem exudate above the certain threshold level after which normal development of cells and tissues becomes impossible.
Instead of usual primary formation of conducting elements of xylem there is an active formation of the phloem sieve tubes and parenchymal cells of wood and bark.
A leaf apparatus of a tree is a source of photoassimilates entering the stem.
In this connection seasonal developing of the leaf apparatus in forms of a silver birch with a normal and abnormal structure of a trunk tissues has been investigated.
According to these findings we came to the conclusion that the leaf apparatus of a Karelian birch promoted formation of a large amount of photoassimilates inflow of which to the zones of bud formation provided their best development, compared with a usual silver birch.
Inflow of excessive transport sucrose to the unit of a trunk mass of a Karelian birch, obviously, has restriction from the throughput capacity of the sieve elements that results in intensive radial unloading of the conducting phloem and to a sucrose concentration increase in the cambial zone.
The latter induces amplified differentiation of the storage parenchyma cells occurrence of which is the beginning of structural disorder in the secondary conducting tissues.
The increase in a share of storage parenchyma causes accumulation of the greater stock of photoassimilates in the trunk.
Their mobilization after spring awakening of the plant causes more intensive development of the leaf apparatus.
Our researches have shown, that biochemical inductor of the changes in the program of differentiation of cambial zone cells during the formation of structural anomalies of the trunk which are pertinent to Karelian birch is an increase of sucrose concentration in the phloem exudate above the certain threshold level after which normal development of cells and tissues becomes impossible.
Instead of usual primary formation of conducting elements of xylem there is an active formation of the phloem sieve tubes and parenchymal cells of wood and bark.
A leaf apparatus of a tree is a source of photoassimilates entering the stem.
In this connection seasonal developing of the leaf apparatus in forms of a silver birch with a normal and abnormal structure of a trunk tissues has been investigated.
According to these findings we came to the conclusion that the leaf apparatus of a Karelian birch promoted formation of a large amount of photoassimilates inflow of which to the zones of bud formation provided their best development, compared with a usual silver birch.
Inflow of excessive transport sucrose to the unit of a trunk mass of a Karelian birch, obviously, has restriction from the throughput capacity of the sieve elements that results in intensive radial unloading of the conducting phloem and to a sucrose concentration increase in the cambial zone.
The latter induces amplified differentiation of the storage parenchyma cells occurrence of which is the beginning of structural disorder in the secondary conducting tissues.
The increase in a share of storage parenchyma causes accumulation of the greater stock of photoassimilates in the trunk.
Their mobilization after spring awakening of the plant causes more intensive development of the leaf apparatus.
Authors
N.N. Nikolaeva, L.L. Novitskaya
Keywords
silver birch, Karelian birch, assimilative apparatus structure, abnormal wood
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