Comparative investigation on acoustic emission and changes in beech tension and opposite woods (Fagus sylvatica L.) microstructure were performed in wood drying process. The opposite wood generates several times higher numbers of acoustic impulses than tension wood. Tension wood activity decreases with increase of gelationous fibres fraction in wood tissue. In opposite wood dominate the cracks of high acoustic activity in the middle lammella (intercell), while in tension wood the most common is separation of gelatinous layer (G-layer) from middle layer of the secondery wall (S2-layer) (interwall) characterized by low acoustic activity.

The morphology of cellular elements of juvenile wood of spruce has, in comparing to mature wood, different parameters. Subsequently, indented growth ring zones, caused by genetic predisposition and cambial injury, can significantly change the morphology of these tissues. The aim of the paper compared the morphology of cellular elements of juvenile wood originating in the indented and the normal growth rings. The results confirmed a significant difference in the proportion, the dimensions and shape of parenchyma cells and tracheids. While, in zones containing the indented growth rings the proportions were 15.6 % and 84.4 %, in normal growth rings were 10.4 % and 89.6 %. Tracheids in the indented growth ring zones were shorter and narrower (1.47 mm and 25.4 µm), but in normal growth ring zones longer and wider (2.14 mm and 28.3 µm). Tracheids from marginal and central zones normal growth rings showed considerable inhomogeneity in longitudinal shape (they were twisted). On the basis of change tissue morphology in the juvenile growth phase we can expect the impact of these growth disproportions on the quality production of pulp and paper, mainly in assortments with small diameter.

No abstract

Key message Fungal infection was outlined as a potential reason for the onset of indented annual growth ring formation during the juvenile phase of hazel wood growth. Annual growth ring indentations resulted from the formation of disturbed zones which originated solely in close proximity to leaf traces. Context Hazel wood is an abnormal type of woody tissue that is formed as a result of exogenous stimuli that may trigger long-term responses in the cambium. Cambial responses produce anatomical alterations in the surrounding xylem tissue that can be observed as an indentation of annual growth rings. The chemical profiles of lignan hydroxymatairesinol may provide an indication of its possible role in the protection of a living tree against the spread of a fungal or microbial infection at the onset of indentation. Aims The objectives of this study were to reveal the anatomical differences in the altered woody tissue of Picea abies hazel wood at both the onset and the later stages of annual growth ring indentation and to determine the chemical profiles for hydroxymatairesinol upon elicitation by a fungal infection in the disturbed zones. Methods Light and scanning electron microscopy observations were carried out on radial, tangential, and cross sections of hazel wood zones separated from P. abies stems. Concentrations of hydroxymatairesinol were determined for both the disturbed zones and the non-indented zones using a gradient high-performance liquid chromatography. Results The formation of disturbed zones was accompanied by significant changes in both the direction and width of the tracheids which produced an abnormal formation of intertwined and twisted tracheids. Fungal hyphae, radial cell wall cracks, and unusually large cross-field pitting were all found in the tracheids of the disturbed zones. Conclusion The content of hydroxymatairesinol in the acetone extract determined from the disturbed zones was 3.4 times greater than that present in the non-disturbed tissues. By means of vascular dysfunction in the leaf traces, host trees responded to the fungal infection by plugging the lumens of conductive leaf trace tissue and filling the vascular pathway with polyphenolic compound deposits.

A total of 28 seeds of Phoenix canariensis, collected on the littoral of Croatia (former Yugoslavia) in August 1998, were brought to the Slovak Republic in order to grow palm trees In artificial conditions. Surprisingly, the seeds yielded 284 specimens of bark beetles which were identified as Dactylotrypes Iongicollis. This is the first evidence for the introduction of D. longicollis to the Slovak Republic.