No description available.

No description available.

No description available.

KAŠPAR M.: Analysis of xylogenis and floemogenesis of Norway Spruce (Picea abies (L.) Karst.) during two growing seasons. The thesis deals is focused on finding and evaluating the creation of wood and phloem of Norway spruce during the vegetation period 2015 and 2016 at the reasearch area Rájec-Němčice. Six representative trees were selected on the surface and samples were taken periodically. Permanent microscopic slides were prepared and examined for the samples obtained. The activity of cambium, the different phases of differentiation of wood and bast elements and the rate of growth using Gompertz function were evaluated. The data collected for each year were compared with each other and compared with the results of other authors. Growth variations were noted within two growing seasons. Statistically significant differences were seen in the number of kambia cells, whether in dormancy or during the active period. There were statistically significant differences at the time of termination of the individual cell phases. The different values of the years also resulted from the results of the Gompertz function. Generally speaking, in 2016 the growth dynamics was more intense and the number of cells generated was higher than in the previous year.

Monitoring of cambial activity in sample trees during growing season 2013 and 2014 was the aim of this thesis. This study summarizes the findings about the variations in the cambial zone, the radial increment of stems, the differentiation process of xylem and phloem formation. The changes in cambial zone observed at the cellular level were made possible by the periodical sampling. Periodical samples - microcores were taken with the Trephor tool at weekly intervals from March to November. The permanent microscope slides were made of microcores. The number of the permanent microscope slides provided information about the actual cambial activity at the time of sampling. Variations and results of the cambial activity were evaluated in relation to the climatic conditions of the research site. The unfavorable climatic conditions were noted in the growth response of sample trees, especially in 2014. The radial xylem increment was 1012±489 µm in 2014. The maximum daily increment of xylem 13±4 µm was recorded between 29 May and 26 June 2014. The total tree ring width was 1655±444 µm in 2013. The maximum daily increment of xylem 27±13 µm was recorded between 13 June and 11 July 2013. The xylem formation lasted for 91 days in 2013. The xylem formation was 9 days shorter in 2014.

Scots pine (Pinus sylvestris L.) is a long-term economically preferred woody species not only from the standpoint of its wood production but also thanks to its tolerance to extreme climatic factors, environmental modesty, and resistance to drought stress. In recent years, however, due to the action of the changing climatic conditions, this economically significant woody species withers. Its increment in the natural ecotype is affected by the adaptability to the increasing intensity of temperature extremes (prolonged heat waves). The combination of the lack of precipitation and extremely high air temperatures (even in the spring season) will significantly affect the resistance of this woody species to drought stress. This thesis is focused on the analysis of the secondary xylem and phloem cells formation of Scots pine depending on the physiological and morphological changes due to the affecting drought stress. Within the scope of the forming radial cells in individual growing seasons (2013–2016), it has been evaluated how the synergy of the specific factors affecting the overall anatomic structure of the annual ring and the vitality of the examined woody species was expressed in the formation, differentiation, and overall structure of the cells. During the four growing seasons (2013–2016), micro-cores (diameter 1.8 mm) were taken in weekly intervals in the research area in Sobesice of xylem and phloem (including the cambial zone) using the Trephor increment borer. From these micro-cores, permanent microscopic slides of the cross-section were made, on which the analysis of the cambial activity, cell formation, cell differentiation with time, and the evaluation of the morphometric parameters of the formed of xylem and phloem cells were performed. It was found that in each monitored growing season, the drought stress has shown, which was reflected by the dropped of the soil water potential (below -1 MPa) and the intensity of transpiration, which led to the stress reaction of the cambium. The reaction of the drought-stressed cambial zone has been expressed by the decreased activity (a sudden drop of the number of dividing cells) and subsequently, during the recurrence of precipitation, by the reactivation when an increase of the number of dividing cells was observed again. This factor initiated the formation of the intra-annual density fluctuations (IADF), i.e. the formation of the so-called false annual ring. The sensitive reaction of the cambium to the drought stress affected the cell production time, the number of formed cells, and also the time of differentiation of individual tracheids, which was expressed by the reduction of the radial dimensions and cell wall thickness of the tracheids. The artificially induced stress by stem girdling intensified the concurrent drought factor and in the area below the girdling, the cambial activity has stopped within two weeks after the performed treatment. The formed cells were not fully differentiated, so the zone of typically thick-walled cells of latewood was missing in the annual ring. The following growing season, the radial increment was only formed in the area above the girdling (without the latewood zone) and in the second half of the growing season, the trees gradually died. The activity of the plant hormone IAA was also affected by the drought in the summer season, when its concentration dropped below the measurability threshold (2 µg sample-1). At the time of the IAA concentration drop, latewood tracheids began to form and the phloem cell formation was completed. The synthesis and activity of the soluble low-molecular carbohydrates correlated with the course of the cambial activity and the cell differentiation phases, where the dynamics of the concentration also matched the timing of the formation of the individual cell formation phases. With phloem cells, a significant variability in the morphological dimensions has not been observed compared to xylem cells. The phenology of the needles indicated the cell wall formation phases and the initiation of the latewood tracheids. Due to the fact that the needles were fully formed in the season of the spring tracheids formation, their phenology did not reflect the drought stress which was recorded mainly in the summer season. Also, the increment of phloem was formed in the spring season. It has been presented for a long time that coniferous woody species react to the drought stress by thicker cell walls formation of the latewood tracheids. However, it has been observed within the scope of the research of this thesis that the water deficit affected the cambial activity, which has expressed itself on the intensity of the cell formation and the time of their differentiation. Due to this process, tracheids with smaller radial dimensions and a narrower cell wall were formed. This gradually causes structural changes of the formed annual ring, where the typically earlywood and latewood tracheids (classified according to radial dimensions and thicknesses of cell walls) may form independently on the growth seasonality. Especially in cases of IADF formation or in combination with the case where latewood is not even formed, a problem with the validity of the classification according to the so-called Mork’s criterion begins to occur. The understanding of the effect of the specific metabolic and physiological changes on xylem and phloem formation of Scots pine helps to clarify the issues of forestation and overall wood production of this economically significant woody species.