Populus Ussuriensis Kom Research Articles

The effect of seasonal temperature difference on estimated wood density in Populus ussuriensis Kom. trees by the resistance drilling method

ABSTRACT Wood density is a main determinant of wood quality assessment for wood end-use and plantation trees. The resistance drilling method (RST) is one of the rapid assessment methods of wood density for standing trees. As the season changes, the water within trees occurs to freeze and is expected to indirectly affect RST results. However, the impact of ambient temperature is unknown. To investigate the effect of seasonal temperature difference on estimated wood density, the RST of Populus ussuriensis Kom. trees was examined across different seasons. A good linear regression model between average wood density and RST was established at normal temperature during summer, with a coefficient of determination of 0.708. The average RST of sapwood and heartwood increased by 6% to 22% from autumn (−5–0°C) to winter (−20–−10°C) compared to normal temperature in summer. Correspondingly, the average wood density estimated by RST increased by 4% to 16% from autumn to winter relative to normal temperature. The quadratic polynomial functions described the relationship between relative RST, relative wood density and seasonal temperature, with coefficients of determination over 0.922. Seasonal temperature had a significant effect on wood density, which was overestimated by RST in winter. This overestimation should be considered in the RST application.

Physiological and Transcriptome Analysis on Diploid and Polyploid Populus ussuriensis Kom. under Salt Stress.

Populus ussuriensis Kom. is a valuable forest regeneration tree species in the eastern mountainous region of Northeast China. It is known that diploid P. ussuriensis (CK) performed barely satisfactorily under salt stress, but the salt stress tolerance of polyploid (i.e., triploid (T12) and tetraploid (F20)) P. ussuriensis is still unknown. In order to compare the salt stress tolerance and salt stress response mechanism between diploid and polyploid P. ussuriensis, phenotypic observation, biological and biochemistry index detections, and transcriptome sequencing (RNA-seq) were performed on CK, T12, and F20. Phenotypic observation and leaf salt injury index analysis indicated CK suffered more severe salt injury than T12 and F20. SOD and POD activity detections indicated the salt stress response capacity of T12 was stronger than that of CK and F20. MDA content, proline content and relative electric conductivity detections indicated CK suffered the most severe cell-membrane damage, and T12 exhibited the strongest osmoprotective capacity under salt stress. Transcriptome analysis indicated the DEGs of CK, T12, and F20 under salt stress were different in category and change trend, and there were abundant WRKY, NAM, MYB and AP2/ERF genes among the DEGs in CK, T12, and F20 under salt stress. GO term enrichment indicated the basic growth progresses of CK, and F20 was obviously influenced, while T12 immediately launched more salt stress response processes in 36 h after salt stress. KEGG enrichment indicated the DEGs of CK mainly involved in plant–pathogen interaction, ribosome biogenesis in eukaryotes, protein processing in endoplasmic reticulum, degradation of aromatic compounds, plant hormone signal transduction, photosynthesis, and carbon metabolism pathways. The DEGs of T12 were mainly involved in plant–pathogen interaction, cysteine and methionine metabolism, phagosomes, biosynthesis of amino acids, phenylalanine, tyrosine and tryptophan biosynthesis, plant hormone signal transduction, and starch and sucrose metabolism pathways. The DEGs of F20 were mainly involved in plant hormone signal transduction, plant–pathogen interaction, zeatin biosynthesis, and glutathione metabolism pathways. In conclusion, triploid exhibited stronger salt stress tolerance than tetraploid and diploid P. ussuriensis (i.e., T12 > F20 > CK). The differences between the DEGs of CK, T12, and F20 probably are the key clues for discovering the salt stress response signal transduction network in P. Ussuriensis.

Selection and Validation of Reference Genes for the qRT-PCR Assays of Populus ussuriensis Gene Expression under Abiotic Stresses and Related ABA Treatment

Populus ussuriensis Kom. is one of the most important tree species for forest renewal in the eastern mountainous areas of Northeast China due to its fast growth, high yield, and significant commercial and ecological value. The selection of optimal reference genes for the normalization of qRT-PCR data is essential for the analysis of relative gene expression. In this study, fourteen genes were selected and assessed for their expression stability during abiotic stress (drought, high salinity, and cold stress) and after the treatment with the drought-related hormone ABA. Three algorithms were used, geNorm, NormFinder, and BestKeeper, and a comprehensive ranking of candidate reference genes was produced based on their output. The most appropriate reference genes were UBQ10 and RPL24 for drought and ABA treatment, UBQ10 and TUB3 for cold stress, and UBQ10 and 60S rRNA for high salinity. Overall, UBQ10 was the most stable reference gene for use as an internal control, whereas PP2A was the least stable. The expression of two target genes (P5CS2 and GI) was used to further verify that the selected reference genes were suitable for gene expression normalization. This work comprehensively assesses the stability of reference genes in Populus ussuriensis and identifies suitable reference genes for normalization during qRT-PCR analysis.

Preliminary study on genetic variation of growth traits and wood properties and superior clones selection of Populus ussuriensis Kom.

In this study the genetic variation of growth traits and wood properties was assessed in 45 clones of Populus ussuriensis Kom. grown in a 10-year-old experimental forest located in Northeastern China and a preliminary selection of superior clones was performed based on multi-trait selection index. The following traits were analyzed: tree height, H; diameter at breast height, DBH; volume, V; basic wood density, BWD; fiber length, FL; fiber length-width ratio, FL/W; microfibril angle, MA; cell wall percentage, CWP; fiber double wall thickness, FWT; vessel proportion, VP; wood fiber proportion, FP; wood ray proportion, RP; holocellulose content, HC. The results revealed significant differences (P<0.05) in DBH, V, BWD, FWT, VP and FP among different clones. Broad-sense heritabilities for growth traits and wood properties ranged from 0.020 to 0.749, therefore growth traits and wood properties are moderately or weakly controlled. Negative correlations between growth traits and most wood properties were also found. According to the multi-trait selection index at a selected rate of 10% and survival rates, 3 superior clones (I18, H16, C13) were selected, and the DBH, V, BWD, FL and FP of superior clones were higher than those of all clones by 2.83%, 9.81%, 3.40%, 6.59% and 0.31%, the MA, FWT, VP were lower than those of all clones by 7.54%, 0.39%, 2.12%, respectively. These superior clones could be used as starting breeding material for P. ussuriensis.

Morphological and Physiological Responses of Populus ussuriensis Kom. to Drought Stress

Morphological and Physiological Responses of Populus ussuriensis Kom. to Drought Stress

Wood density and fiber dimensions of root, stem, and branch wood of Populus ussuriensis Kom. trees

In order to determine the possibility of whole-tree wood utilization of a native tree species in Northeast China (P. ussuriensis), this study investigated the air-dried wood density and fiber dimensions for each ring in the branch, stem, and root wood of the tree species. The results showed significant differences in wood densities and fiber dimensions among tree positions (p &lt;0.05). The root had the highest average density (0.596 g/cm3), and branch had the lowest average density (0.506 g/cm3). The root and branch wood exhibited larger fibers than that of the stem wood. The root wood had the highest average fiber wall (6.038 µm). The fiber wall of branch wood appeared thinner than the stem wood, although the difference was not statistically significant. The radial pattern of wood density and fiber dimensions indicated that branches and roots did not have juvenile wood such as was found in the stems. The study concludes that the use of branch or root wood of P. ussuriensis would be favorable for papermaking or wood-based panels.

Drought stress tolerance analysis of Populus ussuriensis clones with different ploidies

The selection of drought-tolerant plants is an important aspect of plant breeding. We studied physiological and biochemical mechanisms of different ploidies of Populus ussuriensis Kom. that relate to drought stress tolerance. We used a 5% (v/v) polyethylene glycol (PEG-6000) solution to simulate drought stress. We recorded leaf phenotypes including color, dry area and curl degree. We evaluated sequential variations in some drought stress tolerance-related physiological and biochemical indices and compared these among diploid clones (CK), triploid clones (T12) and tetraploid clones (F20). T12 leaves exhibited slightly more drought stress damage than CK and F20 leaves. CK leaves suffered the most severe drought stress damage. The physiological and biochemical indices of the different ploidies differed significantly 12 days after drought stress treatment. The activities of superoxide dismutase, peroxidase, catalase and proline in the triploid (T12) leaves were the highest. The relative electric conductivity and malondialdehyde content of T12 leaves were the lowest. The index values of F20 were between those of the diploid and triploid. In consideration of these results, the drought resistance of the three different ploidies of P. ussuriensis can be ranked as T12 > F20 > CK. We speculate that the gene expression patterns of polyploid clones of poplar will change after genome doubling and that some of the drought stress tolerance-related physiological and biochemical indices will be improved, resulting in greater drought tolerance of polyploid clones.

Ectopic expression of Limonium bicolor (Bag.) Kuntze DREB (LbDREB) results in enhanced salt stress tolerance of transgenic Populus ussuriensis Kom

High salinity is one of the most common abiotic stresses that plants have to confront, and selecting salt-tolerant plants is becoming a very important task in breeding. In this study, non-transgenic (NT) and three LbDREB-transgenic Populus ussuriensis Kom. (Dr22, Dr8, and Dr2) lines were treated with 150 mM NaCl. The salt tolerance of NT, Dr2, Dr8, and Dr22 were evaluated and compared. Phenotypic observation, chlorophyll content detection and leaf salt injury index calculation suggested NT exhibited more severe salt injury symptoms and weaker photosynthetic capacity than Dr2, Dr8, and Dr22. LbDREB gene exhibited opposite temporal expression patterns with no apical meristem (NAM), trihelix transcription factor (GT-1) and WRKY transcription factor 70 (WRKY70), and consistent expression patterns with Cu–Zn superoxide dismutase and peroxidase-PO1 genes, in Dr2, Dr8, and Dr22 under salt stress. The superoxide dismutase and peroxidase activities of transgenic lines were higher than NT plants during the salt stress treatment. Malonaldehyde accumulation in NT leaves was more significant than in transgenic leaves, while proline accumulation in NT leaves was much less than that in transgenic leaves under salt stress. The root to shoot ratios were significantly increased in Dr2, Dr8, and Dr22 plants, but were slightly decreased in NT plants, 12 days after salt stress treatment. The relative water content of NT leaves decreased more than transgenic leaves, meanwhile, the relative electrolytic leakage of NT leaves increased more significantly than transgenic leaves after salt stress. In summary, Dr2, Dr8, and Dr22 exhibited stronger salt stress tolerance than NT. The transgenic lines Dr2, Dr8, and Dr22 can serve as alternative salt-tolerant germplasm resources in P. ussuriensis breeding.

Fabrication of biomass-derived C-doped Bi2WO6 templated from wood fibers and its excellent sensing of the gases containing carbonyl groups

In this work, wood fibers (Populus ussuriensis Kom) were used as biotemplate to synthesize Bi2WO6. In corporation of biomass-derived C, the sensitivity to the gases containing carbonyl groups of gas sensors is improved. The experimental results showed that the C-doped Bi2WO6 sensors presented high sensitivities to acetone, acetic acid and ethyl acetate molecules at low temperature (370°C). The gas sensitivities of C-doped Bi2WO6 sensors on exposure to 1000ppm of acetone, acetic acid and ethyl acetate gas are 4.4, 3.0 and 2.4 times higher than that exposure to 1000ppm of ethanol, respectively. That is because the biomass-derived C can adsorb more oxygen molecules and the carbonyl groups in the gases can react with more oxygen molecules and release more electrons leading a resistance decrease of the sensors due to the electronic structure of carbonyl groups. The reported strategy opened up a new way for the development of gas sensors.

Effect of laminated structure design on the mechanical properties of bamboo-wood hybrid laminated veneer lumber

The effects of veneer orientation and loading direction on the mechanical properties of bamboo-bundle/poplar veneer laminated veneer lumber (BWLVL) were investigated by a statistical analysis method. Eight types of laminated structure were designed for the BWLVL aiming to explore the feasibility of manufacturing high-performance bamboo-based composites. A specific type of bamboo species named Cizhu bamboo (Neosinocalamus affinis) with a thickness of 6 mm and diameter of 65 mm was used. The wood veneers were from fast-growing poplar tree (Populus ussuriensis Kom.) in China. The bamboo bundles were obtained by a mechanical process. They were then formed into uniform veneers using a one-piece veneer technology. Bamboo bundle and poplar veneer were immersed in water-soluble phenol formaldehyde (PF) resin with low molecular weight for 7 min and dried to MC of 8–12 % under the ambient environment. All specimens were prepared through hand lay-up using compressing molding method. The density and mechanical properties including modulus of elasticity (MOE), modulus of rupture (MOR), and shearing strength (SS) of samples were characterized under loading parallel and perpendicular to the glue line. The results indicated that as the contribution of bamboo bundle increased in laminated structure, especially laminated on the surface layers, the MOE, MOR and SS increased. A lay-up BBPBPBB (B-bamboo, P-poplar) had the highest properties due to the cooperation of bamboo bundle and poplar veneer. A higher value of MOE and MOR was found for the perpendicular loading test than that for the parallel test, while a slightly higher SS was observed parallel to the glue line compared with perpendicular loading. Any lay-up within the homogeneous group can be used to replace others for obtaining the same mechanical properties in applications. These findings suggested that the laminated structure with high stiffness laid-up on the surface layers could improve the performance of natural fiber reinforced composites.

Analysis of Nondestructive Testing for Mechanical Properties of LVL at Different Relative Humidities Based on Fuzzy and Classical Mathematics

Laminated veneer lumber (LVL) panels made from poplar (Populus ussuriensis Kom.) and pine (Pinus sylvestris L. var. mongolica Litven.) veneers were tested for mechanical properties in this work. Four different nondestructive testing (NDT) methods and the static bending test were conducted on the LVL. The NDT methods included the longitudinal vibration method, longitudinal transmission method, and in-plane and out-plane flexural vibration methods. The effects of relative humidity on the modulus of elasticity (MOE) and bending strength (MOR) of LVL with vertical load were investigated. Four relative humidities were tested, namely 40%, 50%, 60%, and 70%. The feasibility of NDT testing on LVL was analyzed by fuzzy and classical mathematics. The results showed that the MOE and MOR of LVL diminished with an increase of relative humidity, and the analysis results of fuzzy neartude and correlation coefficients were same. There was a good linear correlation between NDT results and MOE or MOR of poplar and pine LVL.

Analysis of the Microstructure and Mechanical Properties of Laminated Veneer Lumber

In this paper, four different nondestructive testing (NDT) methods and static bending tests were done on poplar (Populus ussuriensis Kom.) and birch (Betula platyphylla Suk.) Laminated Veneer Lumber (LVL). The effects of compression ratio on the modulus of elasticity (MOE) and modulus of rupture (MOR) of LVL with vertical load and parallel load were investigated. There were four compression ratios: 8.1%, 18.3%, 26.5%, and 33.1%. The microscopic structure of LVL was analyzed with a scanning electron microscope (SEM). Results showed a strong correlation between each dynamic Young’s modulus and the static MOR of LVL; the MOE and MOR of LVL changed with the increase of compression ratio. MOE and MOR were greatly increased when the compression ratio increased from 18.3% to 26.5%, and the microstructure of LVL changed greatly between different compression ratios by birch and poplar species.

Comparison of decay resistance of wood and wood-polymer composite prepared by in-situ polymerization of monomers

Fast-growing plant wood Populus ussuriensis Kom, and Micheliamacclurel wood were respectively modified by formation of wood-polymer composite to improve their decay resistance. Two functional monomers, glycidyl methacrylate and ethylene glycol dimethacrylate, added with a few Azo-bis-isobutryonitrile as initiator, and maleic anhydride as catalyst, were first impregnated into wood cell lumen under a vacuum-pressure condition, and then in-situ polymerized into copolymers through a catalyst-thermal treatment. The decay resistances of untreated wood and wood-polymer composites were assessed by weight loss and compared by SEM observations. SEM and FTIR analysis indicated that the in-situ polymerized copolymers fully filled up wood cell lumen and also grafted onto wood cell walls, resulting in the blockage of passages for microorganisms and moisture to wood cell walls. Thus, the decay resistance of poplar wood-polymer composite and Micheliamacclurel wood-polymer composite against brown rot fungus and white rot fungus in terms of weight loss achieved 3.43–3.92% and 1.04–1.33%, improved 95.06–95.18% and 95.10–95.35% than those of untreated poplar wood and Micheliamacclurel wood, respectively; and also respectively higher than that of boron-treated wood. The SEM observations for the decayed poplar wood, Micheliamacclurel wood and their corresponding treated wood also showed the remarkable improvement of decay resistance of wood after such treatment, which effectively protected wood from degradation by fungi.

Characterization and durability of wood-polymer composite prepared by in-situ polymerization of methyl methacrylate and styrene

The current study demonstrates the effect of in-situ formation of polymer from vinyl monomers on the morphology and durability of wood. Mixed monomers of methyl methacrylate (MMA) and styrene (St) (1:1 molar ratio) were effectively vacuum/pressure impregnated into the cellular structure of a fast-growing poplar wood, Populus ussuriensis Kom, and then underwent a catalyst-thermal process to polymerize and form wood-polymer composite. Scanning electron microscopy (SEM) observation shows that polymer converted from monomers almost filled up wood cell cavities. Fourier transform infrared (FTIR) analysis indicates that the polymer mainly physical interacted with wood matrix. X-ray diffraction (XRD) analysis suggests that the in-situ generated polymer mainly remained as an amorphous form in cell lumen. The block of wood cavities by polymer coupled with the water resistance of polymer resulted in remarkable improvement of decay resistance and dimensional stability of wood. Key words: Wood-polymer composite, characterization, morphology, durability, methyl methacrylate, styrene.

Effect of polymer in situ synthesized from methyl methacrylate and styrene on the morphology, thermal behavior, and durability of wood

AbstractA novel fast‐growing poplar wood, Populus ussuriensis Kom, was prepared into wood‐polymer composite by the in situ polymerization of methyl methacrylate and styrene through a vacuum/pressure and subsequent catalyst‐thermal process. scanning electron microscopy observation, FTIR, X‐ray diffraction, dynamic mechanical analysis, and thermogravimetric/derivative thermogravimetric analysis indicated that the resulted polymer well filled up wood cell lumen in an amorphous form and reinforced wood matrix, which resulted in the improvement of glass transition temperature, storage modulus, and thermal stability of wood. The decay resistance and dimensional stability of wood were also improved. Such wood‐based composite could be potentially used as reinforced material in construction fields. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Mechanical Properties of Wood-Polymer Composite Prepared by &lt;i&gt;In-Situ&lt;/i&gt; Polymerization of Methyl Methacryalte and Styrene

Fast-growing poplar wood, Populus ussuriensis Kom, was used to prepare novel wood-polymer composite by the in-situ polymerization of methyl methacrylate (MMA) and styrene (St). SEM observation and FTIR analysis indicated that the resulted polymer well filled up wood cell lumen and physically reinforce wood matrix. The test results also proved that the mechanical properties of wood including modulus of rupture, modulus of elasticity, compression strength and hardness of were improved by 68.28%, 110.27%, 62.43%, 357% over those of Untreated Wood, respectively. Such wood-based composite could be potentially used as reinforced material in construction fields.

Characterization of Wood-Polymer Composite Fabricated by Polymerization of Methyl Methacrylate and Styrene within Wood

The fast-growing poplar wood, Populus ussuriensis Kom, was prepared into wood-polymer composite by the in-situ polymerization of methyl methacrylate (MMA) and styrene (St) under vacuum/pressure and subsequent catalyst-thermal conditions. SEM observation, FTIR, XRD and DMA analysis indicated that the resulted polymer well filled up wood cell lumen in an amorphous form and physically reinforce wood matrix, which resulted in the improvement of glass transition temperature and storage modulus of wood. Such method could endow low-quality wood with potential value-added applications.

MECHANICAL PROPERTIES ANALYSIS AND RELIABILITY ASSESSMENT OF LAMINATED VENEER LUMBER (LVL) HAVING DIFFERENT PATTERNS OF ASSEMBLY

Laminated Veneer Lumber (LVL) panels made from poplar (Populus ussuriensis Kom.) and birch (Betula platyphylla Suk.) veneers were tested for mechanical properties. The effects of the assembly pattern on the modulus of elasticity (MOE) and modulus of rupture (MOR) of the LVL with vertical load testing were investigated. Three analytical methods were used: composite material mechanics, computer simulation, and static testing. The reliability of the different LVL assembly patterns was assessed using the method of Monte-Carlo. The results showed that the theoretical and ANSYS analysis results of the LVL MOE and MOR were very close to those of the static test results, and the largest proportional error was not greater than 5%. The veneer amount was the same, but the strength and reliability of the LVL made of birch veneers on the top and bottom was much more than the LVL made of poplar veneers. Good assembly patterns can improve the utility value of wood.

Physiological and biochemical responses to low temperature stress in hybrid clones of Populus ussuriensis Kom. × P. deltoides Bartr

Cuttings of three hybrid clones of P. ussuriensis × P. deltoides were exposed to different low temperatures (cold and freezing) for 24 h, or consecutive low temperatures (5°C, 0 to 120 h), to determine physiological and biochemical responses to cold stress in these woody plants. Soluble sugar and protein contents increased in the three clones under cold (10, 5°C) stress, malondialdehyde (MDA) concentrations, electrolytes leak and activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX) and glutathione reductase (GR) also variously increased at 10, 5, and 0°C. While under lower temperatures (-5, -10, and -15°C) treatment, levels of all except electrolytes leak and MDA gradually decreased relatively. During consecutive low temperature (5°C) treatment, concentrations of soluble protein and MDA, electrolytes leak and activities of CAT, APX and GR increased immediately or after 3 h, however, soluble sugar concentrations and SOD and POD activities slightly decreased at the beginning of the treatment; subsequently increased quickly, and then declined. When exposed to different (10, 5, 0, -5, and -10°C) and consecutive (5°C, after 12 or 24h) low temperature stresses, there were significant differences between the three clones. Levels of soluble sugar and soluble protein, and SOD, CAT, POD, APX and GR activities were relatively higher in clone UD183 than in UD189 or UD191. Levels of electrolyte leak and MDA were lower than in UD189 or UD191. Poplar hybrid clones thus employ various physiological and biochemical responses and mechanisms for coping with low temperature stress. According to the results of this study, we presume that clone UD183 may acquire much more freezing- tolerance than clones UD189 and UD191. Our research will promote understanding of cold acclimation and freezing-tolerance in poplars, and encourage selection of the best clones for the cold regions of northern China.

Improvement of decay resistance of wood via combination treatment on wood cell wall: Swell-bonding with maleic anhydride and graft copolymerization with glycidyl methacrylate and methyl methacrylate

Poplar wood ( Populus ussuriensis Kom) was modified by a novel combined two-step treatment to improve its decay resistance. Maleic Anhydride (MAN) was first employed to swell and bond to wood cell wall, and then mixed monomers of glycidyl methacrylate/methyl methacrylate (GMA/MMA) were used to graft copolymerization within wood cell lumen. The swelling and bonding of cell wall by MAN, interfacial compatibility between resultant polymer from GMA/MMA monomers and wood cell wall, and decay resistance of all composites were tested and analyzed by Scanning electron microscopy–Energy dispersive X-ray (SEM–EDX), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) apparatus. The results indicate that the volume of poplar wood treated by MAN swells about 9% with about 15% of weight percent gain, and MAN chemically bonds to the cell wall through substitution reaction with hydroxyl group, and the grafting adduct mainly remains as an amorphous form. The resultant Poplar-MAN shows improved decay resistance of 69.79% against brown fungus ( Gloeophyllum trabeum (Pers. ex Fr.) Murr.) and 81.42% against white fungus ( Phanerochaete chrysosporium Burdsall.) over those of untreated Poplar, respectively. After the combined two-step treatment, GMA and MMA are copolymerized within wood cell lumen, and the resultant polymer is also grafted onto wood cell wall, resulting in the improvement of interfacial compatibility between polymer and wood substance without obvious gaps. The decay resistance of the resultant composite from the combined two-step treatment against the brown decay fungus and the white decay fungus is improved by 97.64% and 99.17%, respectively, compared with those of untreated poplar wood; and also more excellent than those of MMA treated wood, GMA/MMA monomers treated wood, organic 3-Iodo-2-Propynyl Butyl Carbamate (IPBC) treated wood and inorganic boron compounds treated wood, respectively.