ABSTRACT
The changes in wood structure in the course of wood formation or any impact of mechanical/chemical treatments on mature wood should be taken into account to understand the processes themselves and/or to control of them. With this reason, we used the light microscopy during the study of wood formation in Pinus syvestris L. and Larix sibirica Ltb. and the impact of acoustic waves on oak (Quercus robitr L.) wood. Annual wood ring formation was studied in some directions: (1) seasonal distribution of the processes of cell wall production by cambium, the development of primary and secondary walls of early-and latewood tracheids during xylem formation in the season and under the effect of external factors on morphological characteristics of tracheids; (2) the presence of starch granules as the index of carbon store in favorable conditions or its expenditure in unfavorable external conditions during phloem development in pine and larch; (3) the biochemical changes in mono-, di-, and polymeric compounds (carbohydrates, organic, and phenolic acids, hemicelluloses, cellulose and lignin) included in biosynthesis and the formation of wall tracheid structure during wood development. Light microscopy was necessary tool to check of cell wall morphogenesis and lignification in pine (Pinus sylvestris L.) callus grown in the different conditions of cultivation to compare lignification in
vivo and in vitro. Light microscopy was also used to study the structure of oak (Quercus robur) wood from different habitats and to estimate the changes in oak wood structure under ultrasound waves. The examples of light microscopy applying in those fields are given in the chapter.
