Search Results (6)

This study investigated the bonding strength and chemical composition (as an influencing factor of adhesion) of red eucalyptus (Eucalyptus camaldulensis) (EUW) and grey poplar (Populus canescens) (GPOW) wood surfaces, comparing their suitability for indoor and outdoor wood-building applications. The research focused on adhesion strength using different coatings and adhesives, including lasure and 2K lacquer. The results showed that whilst both wood species had a conveniently high cellulose content, GPOW had a higher cellulose content (48.21%) than EUW (45.18%). However, EUW demonstrated superiority in tensile shear strength tests when using structural adhesives. Additionally, EUW exhibited stronger pull-off adhesion with 2K lacquer (5.25 MPa) compared with GPOW (3.42 MPa), suggesting that whilst both reached the expectations, EUW was more appropriate for high-stress indoor applications like flooring or wall cladding. EUW and GPOW performed well with lasure, achieving comparable adhesion strengths. EUW had a density of 1020 kg/m³ vs. 575 kg/m³ for GPOW and stronger bonding capabilities than GPOW, which suggests that it is equally suitable for wood applications inside and outside buildings. The study concluded that whilst both wood species met expectations and proved to be suitable for doors, windows, and other wood-building product applications, GPOW was suitable for the production of cellulose-based products, while EUW was worth relying on for its excellent adhesion to coatings and adhesives. Full article

The plastidic 2-C-methylerythritol 4-phosphate (MEP) pathway supplies the precursors of a large variety of essential plant isoprenoids, but its regulation is still not well understood. Using metabolic control analysis (MCA), we examined the first enzyme of this pathway, 1-deoxyxylulose 5-phosphate synthase (DXS), in multiple grey poplar (Populus × canescens) lines modified in their DXS activity. Single leaves were dynamically labeled with ¹³CO₂ in an illuminated, climate-controlled gas exchange cuvette coupled to a proton transfer reaction mass spectrometer, and the carbon flux through the MEP pathway was calculated. Carbon was rapidly assimilated into MEP pathway intermediates and labeled both the isoprene released and the IDP+DMADP pool by up to 90%. DXS activity was increased by 25% in lines overexpressing the DXS gene and reduced by 50% in RNA interference lines, while the carbon flux in the MEP pathway was 25–35% greater in overexpressing lines and unchanged in RNA interference lines. Isoprene emission was also not altered in these different genetic backgrounds. By correlating absolute flux to DXS activity under different conditions of light and temperature, the flux control coefficient was found to be low. Among isoprenoid end products, isoprene itself was unchanged in DXS transgenic lines, but the levels of the chlorophylls and most carotenoids measured were 20–30% less in RNA interference lines than in overexpression lines. Our data thus demonstrate that DXS in the isoprene-emitting grey poplar plays only a minor part in controlling flux through the MEP pathway. Full article

Among fast-growing wood species, poplars (Populus spp.) can be grown well. Thanks to their valuable wood, they also play an important role in the world. In Europe, regarding poplar forest areas, Hungary is ranked second, where the territorial proportion of poplars has not changed in the past ten years, and currently, two-thirds of them are constituted by two species. The proportion of grey poplar (P. × canescens) is 42%, while the proportion of ’Pannonia’ hybrid (P. × euramericana cv. Pannonia) is 22%. With regard to gross wood production, they are second after black locust (Robinia pseudoacacia), and their standing tree volume is significant for up to 30 years of age. The average age of hybrid poplars is 21 years, while that of the natives is 26 years. Its wood is used by the packaging industry (pallets and boxes) and the furniture industry (700,000 m³), the plywood industry (200,000 m³), and the fiber industry (300,000 m³), but it is also an important source for energetic purposes (150,000 m³). Full article

Very high resolution satellite imageries provide an excellent foundation for precise mapping of plant communities and even single plants. We aim to perform individual tree recognition on the basis of very high resolution RGB (red, green, blue) satellite images using deep learning approaches for northern temperate mixed forests in the Primorsky Region of the Russian Far East. We used a pansharpened satellite RGB image by GeoEye-1 with a spatial resolution of 0.46 m/pixel, obtained in late April 2019. We parametrized the standard U-Net convolutional neural network (CNN) and trained it in manually delineated satellite images to solve the satellite image segmentation problem. For comparison purposes, we also applied standard pixel-based classification algorithms, such as random forest, k-nearest neighbor classifier, naive Bayes classifier, and quadratic discrimination. Pattern-specific features based on grey level co-occurrence matrices (GLCM) were computed to improve the recognition ability of standard machine learning methods. The U-Net-like CNN allowed us to obtain precise recognition of Mongolian poplar (Populus suaveolens Fisch. ex Loudon s.l.) and evergreen coniferous trees (Abies holophylla Maxim., Pinus koraiensis Siebold & Zucc.). We were able to distinguish species belonging to either poplar or coniferous groups but were unable to separate species within the same group (i.e. A. holophylla and P. koraiensis were not distinguishable). The accuracy of recognition was estimated by several metrics and exceeded values obtained for standard machine learning approaches. In contrast to pixel-based recognition algorithms, the U-Net-like CNN does not lead to an increase in false-positive decisions when facing green-colored objects that are similar to trees. By means of U-Net-like CNN, we obtained a mean accuracy score of up to 0.96 in our computational experiments. The U-Net-like CNN recognizes tree crowns not as a set of pixels with known RGB intensities but as spatial objects with a specific geometry and pattern. This CNN’s specific feature excludes misclassifications related to objects of similar colors as objects of interest. We highlight that utilization of satellite images obtained within the suitable phenological season is of high importance for successful tree recognition. The suitability of the phenological season is conceptualized as a group of conditions providing highlighting objects of interest over other components of vegetation cover. In our case, the use of satellite images captured in mid-spring allowed us to recognize evergreen fir and pine trees as the first class of objects (“conifers”) and poplars as the second class, which were in a leafless state among other deciduous tree species. Full article

(1) Background: Populus ×canescens (Aiton) Sm. is a fast-growing woody plant belonging to the family Salicaceae. Two poplar genotypes characterized by unique phenotypic traits (TP11 and TP20) were chosen to be characterized and tested for a physiological and transcriptomic response to Cd stress. (2) Methods: A comparative analysis of the effects of exposure to high cadmium (Cd) concentrations (10 µM and 100 µM) of TP11 and TP20 was performed. (3) Results: Neither of the tested Cd concentration negatively affected plant growth; however, the chlorophyll content significantly decreased. The potassium (K) content was higher in the shoots than in the roots. The magnesium concentrations were only slightly affected by Cd treatment. The zinc content in the shoots of TP20 was lower than that in the shoots of TP11. Cd accumulation was higher in the roots than in the shoots. After 10 days of exposure, 10 µM Cd resulted in comparable amounts of Cd in the roots and shoots of TP20. The most significant change in transcript amount was observed in endochitinase 2, 12-oxophytodienoate reductase 1 and phi classglutathione S-transferase. (4) Conclusions: Our study provided new insights for effective assessing the ability of different poplar genotypes to tolerate Cd stress and underlying Cd tolerance. Full article

The study is focused on the surface changes of five hardwoods (oak, black locust, poplar, alder and maple) that were exposed to natural weathering for 24 months in the climatic conditions of Central Europe. Colour, roughness, visual and chemical changes of exposed surface structures were examined. The lowest total colour changes (ΔE*) were found for oak (23.77), the highest being recorded for maple (34.19). Roughness differences after 24-month exposure (ΔR_a) showed minimal changes in poplar wood (9.41); the highest changes in roughness were found on the surface of alder (22.18). The presence of mould and blue stains was found on the surface of maple, alder and poplar. Chemical changes were characterized by lignin and hemicelluloses degradation. Decreases of both methoxy and carbonyl groups, cleavage of bonds in lignin and hemicelluloses, oxidation reaction and formation of new chromophores were observed. In the initial phases of the degradation process, the discoloration was related to chemical changes; in the longer period, the greying due to settling of dust particles and action of mould influenced the wood colour. The data were confirmed by confocal laser scanning microscopy. The obtained results revealed degradation processes of tested hardwood surfaces exposed to external environmental factors. Full article