Populus Euramericana Research Articles

Feeding preferences ofOdontotermes obesus(Rambur) (Isoptera: Termitidae) on different commercial and non-commercial woods from Lahore, Pakistan, under laboratory and field conditions

Odontotermes obesus (Rambur) is a widespread termite species in South Asia causing significant losses annually. Feeding preferences of O. obesus among 18 different wood species were studied in choice and no-choice bioassays conducted under laboratory and field conditions. Weight losses, wood consumption per individual, and survival rate were determined to evaluate feeding preferences of O. obesus. Populus euramericana and Tectona grandis were found to be the most susceptible and resistant woods, respectively. Nine different wood combinations were used in the bioassay under choice laboratory conditions. The maximum feeding of termites was recorded on M. indica and P. euramericana, whereas the minimum was noted on T. grandis and B. bamboo (2.06 and 43.9 mg), respectively. Under no-choice field conditions, the minimum feeding was recorded on T. grandis (8.9 mg) and the maximum on P. euramericana (47.9 mg). Under choice field conditions, O. obesus showed the maximum (82.6 mg) feeding on P. euramericana and th...

원형톱에 의한 속성수 절단 적정 소요동력 산정에 관한 연구

본 연구에서는 단벌기 바이오매스 생산림(Short rotation forest, SRF)에 식재되어 있는 속성수인 이태리포플러(Populus euramercicana)을 이용하여 수확 시 소요되는 동력을 측정하여 수확기계 동력원을 선정하기 위한 기초자료를 제공하기 위하여 수행되었다. 실험 수준은 밀기속도(0.41, 1.25, 2.5 m/s) 3수준, 절단속도(800, 1,000, 1,200 rpm) 3수준, 근원경(50, 70, 90, 110, 130 mm) 5수준으로 선정하였다. 목표로 하는 바이오매스 추정량은 20~30 ton/ha이나 3년 후 수확(근원경 50 mm) 시 이를 못 미치는 10.5 ton로 나타났다. 목표량에 도달할 수 있는 바이오매스 추정량은 근원경 90, 110 mm으로 각각 23.5, 32.5 ton/ha으로 추정되었다. 실험결과, 밀기속도 0.41 m/s에서 최소절단속도(800 rpm)로 절단 시 소요되는 동력은 각각 128.2, 175.8 W로 나타났고, 작업면적이 0.3 ha/h에서 작업능률은 각각 16.5, 22.8 ton/h을 처리할 수 있는 것으로 사료된다. 밀기속도 1.25 m/s에서는 소요되는 동력은 각각 113.8, 153.7 W, 작업면적이 1 ha/h에서 작업능률은 각각 23.5, 32.5 ton/h을 처리할 수 있는 것으로 사료된다. 밀기속도 2.5 m/s에서는 소요되는 동력은 각각 119.8, 166.9 W, 작업면적 2 ha/h에서 작업능률은 각각 47.0, 65.5 ton/ha을 처리할 수 있을 것으로 사료된다. 따라서 목표로 하는 바이오매스 추정량을 처리할 수 있는 밀기속도 1.25, 2.50 m/s, 절단속도 800 rpm 일 때의 수확기계의 동력원을 선정할 수 있을 것으로 사료된다. In this study, Italy poplar(Populus euramericana) was selected for test specimen to measure cutting power when it harvested. The experiment has been controlled as three levels of feed rate (0.41, 1.25 and 2.5 m/s), sawing speed (800, 1,000 and 1,200 rpm), and the five levels of root collar diameter (50, 70, 90 and 110, 130 mm). The harvested volume after 3 years (root collar diameter 50 mm) was 10.5 tons, which falls short of the target amount of biomass is 20~30 ton/ha. In addition, the biomass amount of diameter 90 and 110 mm which reached the target amount were estimated to be 23.5 and 32.5 ton/ha respectively. As a result of experiment, it was found out that power of 128.2 and 175.8 W are consumed in case of cutting with the feed rate of 0.41m/s and minimum sawing speed (800 rpm) respectively. With the working area of 0.3 ha/h, it is considered to present working capacities of 16.5 and 22.8 ton/h respectively. The power consumed at the feed rate of 1.25 m/s is estimated to be 113.8 and 153.7W respectively and working capacity in a working area of 1 ha/h is estimated to be 23.5 and 32.5 ton/h. The power consumed at the feed rate of 2.5 m/s is estimated to be 119.8 and 166.9 W respectively and working capacity in a working area of 2 ha/h is estimated to be 47.0 and 65.5 ton/ha respectively. Therefore, the power source of harvest machine at the feed rate of 1.25, 2.50 m/s and sawing speed of 800 rpm shall be selected as it can process the target amount of estimated biomass.

Salicortin suppresses lipopolysaccharide-stimulated inflammatory responses via blockade of NF-κB and JNK activation in RAW 264.7 macrophages

We isolated the phenolic glucoside salicortin from a Populus euramericana bark extract, and examined its ability to suppress inflammatory responses as well as the molecular mechanisms underlying these abilities, using lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Salicortin inhibited iNOS expression and the subsequent production of NO in a dose-dependent manner in the LPS-stimulated RAW 264.7 cells. Salicortin significantly suppressed LPS-induced signal cascades of NF-κB activation, such as IKK activation, IκBα phosphorylation and p65 phosphorylation in RAW 264.7 cells. In addition, salicortin inhibited the LPS-induced activation of JNK, but not ERK or p38 MAPK. Furthermore, salicortin significantly inhibited production of pro-inflammatory cytokines, such as TNF-α, IL-1β and IL-6 in the LPS-stimulated RAW 264.7 cells. These findings suggest that salicortin may show its anti-inflammatory activity by suppressing the LPS-induced expression of pro-inflammatory mediators through inhibition of NF-κB and JNK MAPK signaling cascades in macrophages. [BMB Reports 2014; 47(6): 318-323]

Feeding preferences of Coptotermes heimi (Isoptera: Termitidae) under laboratory and field conditions for different commercial and non-commercial woods

Coptotermes heimi (Wasmann) is a termite widely present throughout Pakistan and causes detrimental effects in standing trees. In this study, the feeding preferences of C. heimi for 18 different wood species were determined through choice and no-choice trials under laboratory and field conditions. In no-choice laboratory trials, different combinations of wood blocks were used to determine wood consumption by C. heimi. Weight loss, consumption/individual and survival rate were evaluated. Populus euramericana was found to be the most susceptible wood species and Syzygium cumini the most resistant one. Nine different wood combinations were used under choice laboratory conditions; maximum feeding was recorded in P. euramericana and Pinus roxburghii (50.8–24.5 mg). However, minimum feeding was recorded in S. cumini (2 mg) and Tectona grandis (14.9 mg). Under no-choice field conditions, minimum feeding was recorded in S. cumini (9.5 mg) and maximum feeding in P. euramericana (60.5 mg). Under choice field conditions, maximum (58 mg) feeding was recorded in P. euramericana and minimum feeding in S. cumini. Feeding preferences in descending order based on wood consumption as a quantitative parameter documented were as follows: P. euramericana>Ailanthus excelsa>Azadirachta indica>P. roxburghii>Butea monosperma>Morus alba>Bauhinia variegata>Albizia lebbeck>Dalbergia sissoo>Heterophragma adenophyllum>Erythrina suberosa>Cassia fistula>T. grandis>Mangifera indica>Eucalyptus camaldulensis>Jacaranda mimosifolia>Bambusa bamboo>S. cumini.

In Situ Polymerization of Phenolic Methylolurea in Cell Wall and Induction of Pulse–Pressure Impregnation on Green Wood

Impregnation of the cell wall with various chemicals continues to attract interest. For most studies, the method of impregnation is the vacuum-pressure process which is limited by the specimens’ size in thickness and the requirement for low moisture content. In the present study, we impregnated fast-growing poplar (Populus euramericana) green wood by pulse–pressure at 0.7–0.8 MPa for 50 min with phenolic methylolurea, and then the modifier in situ polymerized within the wood cell wall by kiln drying. The microscopy analysis showed that the pulse–pressure impregnation method could be feasible because of the presence of a wide-bore capillary column system in the poplar xylem. As a result, the chemical treatment reduced the hygroscopicity and increased the dimensional stability of wood. Reactions mainly happened within the interfibrillar amorphous region of the cell wall. Among the reactions were etherification and esterification since the covalent bonds formed between modifier methylol groups, wood hydroxyl, and acetic acid derived from hemicelluloses.

永定河沿河沙地杨树人工林蒸腾耗水特征及其环境响应

Poplar plantations are the most prevalent and the fastest expanding plantations in Northern China. However,the high water use of poplars necessitates careful consideration of their suitability for water-stressed regions. It is essential to find out the relationships between the water transpired by poplar plantation and environmental factors during different growing periods,which is very important in poplar plantation sustainable management. Many researchers have done a lot of job on this subject,but few referred to a mature fast growing poplar stand. In the current study the water use and response to environmental factors was evaluated by simultaneous measurements of sap flow using the TDP( Thermal Dissipation Probe)method,micrometeorological conditions and soil moisture in a 13-year old poplar( Populus euramericana cv. 74 / 76 )plantation located on the floodplain of Yongding River in Daxing district,the southern suburb of Beijing,China from 2010 to 2011. Our objectives were to illustrate the water used for transpiration by this 13-year old fast growing poplar plantationand explore how the tree / stand transpiration responses to the different environmental conditions. The results showed that the daily pattern of sap flow was a bell curve. The daily water consumption of individual trees ranged from 6.4 to 59.7 kg / d,varying by season and sapwood which was calculated through the trunk diameter at breast height. On a ground area basis,the growing season transpiration was 114 and 175 mm in 2010 and 2011,respectively. It accounted for 30% —37% of precipitation over the same periods. Compared to earlier reports for poplars in literature,the observed water use was relatively low,likely attributable to growing age and no available irrigation during the study period. A diurnal hysteresis was observed between sap flow and vapor pressure deficit( VPD). Similarly,this situation was also true between sap flow and net radiation( Rn). The hysteresis was greater with high than low soil moisture,suggesting that transpiration did response to the change of soil moisture though indirectly. On daily scale,significant correlations were observed between daily stand transpiration and Rn,VPD and soil moisture. Besides,the relationship between transpiration and soil moisture was related to the depth of soil. The soil moisture under the surface 30—90cm affected transpiration most effectively. When the soil moisture changed,the relationship between stand transpiration and Rn or VPD varied. The growth of VPD stimulated the stand transpiration when it was not greater than 1 k Pa. The over great value of VPD would slow down the growth of stand transpiration. Compared to the data of earlier research at this site,we found that the transpiration of the plantation declined with the stand age. On a monthly and annual scale,transpiration was correlated with rainfall,suggesting limited soil water storage. Simultaneously,we found that during dry months when transpiration could not be satisfied by rainfall,soil water storage offered the water to be transpired. However,the source of soil water storage was also come from rainfall thus the transpiration between 2010 and 2011 were quite different because of great rainfall difference in these two years.

Mechanical Properties of Poplar Laminated Veneer Lumber Modified by Carbon Fiber Reinforced Polymer

Poplar (Populus euramericana cv.) is one of the most important fast-growing tree species in China, but so far its utilization has been limited to nonstructural wood-based panels. The objective of this work was to develop a good understanding of how to improve the mechanical properties of poplar laminated veneer lumber (LVL) with carbon fiber reinforced polymer (CFRP). A theoretical model was successfully developed to predict the bending modulus of elasticity (MOE) of LVL reinforced by CFRP. To validate the model, two different configurations of LVL were made in the laboratory: LVL reinforced with a single layer of CFRP on one side (LVL-SR) and LVL reinforced with a single layer of CFRP on each side (LVL-DR). It was found that the model prediction of the LVL MOE agreed well with the experimental results. LVL reinforced with CFRP had a greater MOE and modulus of rupture (MOR) than the control LVL. The MOE of the LVL-SR and LVL-DR increased by 40% and 67%, respectively.

Earthworm biomass and abundance, soil chemical and physical properties under different poplar plantations in the north of Iran

We evaluated earthworm abundance and biomass in plantations of different poplar species and clones as well as the effect of some soil chemical and physical properties on them. Even-aged poplar species and clones, planted at Safrabasteh Poplar Research Station about 18 years ago in the north of Iran, included: Populus deltoides Bartr. cv. 69/55 (P. d. 69/55), Populus deltoides Bartr. cv. 63/51 (P. d. 63/51), Populus euramericana Guinier. cv. 45/51 (P. e. 45/51), Populus euramericana Guinier. triplo (P. e. triplo), and Populus caspica Born M. (P. caspica), as endemic and endangered poplar species, were selected in this study. Earthworm abundance and biomass, soil texture, bulk and particle density (BD, PD), pH, organic carbon (OC), total nitrogen (N), available phosphorus (P) and exchangeable potassium (K) were evaluated. The results showed that the earthworm abundance and biomass, OC, P and N in P. d. 63/51 were higher than in the other poplar species and clones. The correlation coefficients showed a positive correlation of OC, N and a negative correlation of pH, clay, BD and P with earthworm biomass. Based on the results, compared to the other species and clones P. d. 63/51 creates favourable conditions to produce more organic matter and higher abundance and biomass of earthworms, hence it could be beneficial for maintaining the soil quality status for successive plantings.

Impregnation of poplar wood (Populus euramericana) with methylolurea and sodium silicate sol and induction of in-situ gel polymerization by heating

Abstract Poplar wood (Populus euramericana cv. “I-214”) has been impregnated by pulse dipping at 0.7–0.8 MPa for 30 min with a mixture of methylolurea and sodium silicate, and the sol modifier has been cured within the wood micropores by in situ gel polymerization by kiln drying, so that a Si-O-Si framework was formed. The treated wood acquired higher mechanical strength and its hygroscopicity was lowered. It was demonstrated by X-ray diffraction that sodium silicate crystallized within the interfibrillar region of the cell wall. Fourier transform infrared spectra showed that reactions occurred between the wood-OH, Si-OH, and N-CH2-OH from methylolurea to form C-O-Si and C-O-C bonds. As visible by scanning electron microscopy (SEM), the Si-O-Si framework was embedded in the pretreated wood. Moreover, SEM-energy-dispersive X-ray spectroscopy analysis revealed that the modifier formed layers from various thicknesses ranging from a thin layer on the cell walls up to big amounts filling the lumen.

Cloning and characterization of a putative UDP-rhamnose synthase 1 from Populus euramericana Guinier

L-Rhamnose is a constituent of plant primary cell wall polysaccharides including rhamnogalacturonan-I, rhamnogalacturonan-II, and other natural plant-based compounds. UDP-rhamnose serves as a rhamnose donor whose synthesis is catalyzed by UDP-rhamnose synthase (RHM). A RHM gene, PRHM was cloned from Populus euramericana Guinier. PRHM contains two domains: the NAD dependent epimerase/dehydratase family domain and the RmlD (dTDP-keto-rhamnose-4-keto-reductase) substrate-binding domain. Because the recombinant PRHM did not demonstrate any activity during an in vitro assay, complementation with an Escherichia coli mutant was carried out. The rfbD (dTDP-4-dehydrorhamnose reductase), which encodes an enzyme catalyzing the conversion of dTDP-4-keto-rhamnose to TDP-rhamnose, was mutated in E. coli. The mutant strain B-rfbD was transformed with PRHM gene and a flavonoid rhanmosyltransferase gene, AtUGT78D1. The resulting transformant was able to convert quercetin into quercetin 3-O-rhamnoside in a manner similar to that by the wild type E. coli strain harboring AtUGT78D1. This result indicated that PRHM catalyzed the conversion of UDP-glucose into UDP-rhamnose.

不同土壤水分条件下杨树人工林水分利用效率对环境因子的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 不同土壤水分条件下杨树人工林水分利用效率对环境因子的响应 DOI: 10.5846/stxb201209141295 作者: 作者单位: 北京林业大学,北京林业大学,北京林业大学,Southern Global Change Program，USDA FS,北京林业大学,北京林业大学,北京市林业碳汇工作办公室,北京市林业碳汇工作办公室,Landscape Ecology Ecosystem Science,University of Toledo 作者简介: 通讯作者: 中图分类号: 基金项目: 国家林业行业科研专项(201204102);北京市教育委员会共建项目;北京市林业碳汇工作办公室观测运行基金;教育部重点项目(105027);高等学校博士专项科研基金(20040022013);中美碳联盟USCCC国际合作项目资助 Environmental controls on water use efficiency of a poplar plantation under different soil water conditions Author: Affiliation: Key Laboratory of Soil and Water Conservation and Desertification Combating,Ministry of Education,College of Soil and Water Conservation,Beijing Forestry University,Key Laboratory of Soil and Water Conservation and Desertification Combating,Ministry of Education,College of Soil and Water Conservation,Beijing Forestry University,Key Laboratory of Soil and Water Conservation and Desertification Combating,Ministry of Education,College of Soil and Water Conservation,Beijing Forestry University,Southern Global Change Program，USDA FS,Key Laboratory of Soil and Water Conservation and Desertification Combating,Ministry of Education,College of Soil and Water Conservation,Beijing Forestry University,Key Laboratory of Soil and Water Conservation and Desertification Combating,Ministry of Education,College of Soil and Water Conservation,Beijing Forestry University,Forestry Carbon Sink Management Office,Beijing,Forestry Carbon Sink Management Office,Beijing,Landscape Ecology Ecosystem Science,University of Toledo,Toledo,OH -,USA Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:运用涡度相关(Eddy covariance,EC)开路系统和微气象观测系统,于2007年对位于北京市大兴区永定河沙地杨树(Populus euramericana)人工林与大气间碳、水和能量交换进行了连续测定。通过分析总生态系统生产力(GEP)、蒸发散(ET)以及水分利用效率(WUE=GEP/ET)随相对土壤含水量(REW)的变化趋势,探讨杨树人工林不同土壤水分条件下水分利用效率对气象因子以及下垫面因素的响应,为杨树人工林经营管理提供理论依据。研究结果表明:当REW<0.1时,GEP和ET受到严重水分胁迫的影响维持在较低水平,环境因子对GEP、ET和WUE的影响较小;当0.1<REW<0.4时,GEP和ET随着土壤体积含水量(VWC)的增加而增大,WUE随VWC的增大而减小;REW>0.4时,气象因子是影响碳固定和水分损耗的主要原因,由于ET对气象因子变化的响应较GEP更为敏感,因此,WUE随空气饱和水汽压差(VPD)的增大而减小。沙地土壤保水能力较差,不能保证土壤水分被植物有效利用,因此当VWC处于5.2%-8.8%(0.1<REW<0.4)范围时,碳固定与水分消耗达到最高效率。研究表明杨树人工林WUE随降水变化而变化,未来气候变化和变异有可能影响杨树林耗水和生产力之间的关系。 Abstract:An open path eddy-covariance (EC) system and a microclimate monitor system were employed to continuously measure the carbon, water, and energy exchange between a poplar (Populus euramericana) plantation and the atmosphere during the growing season of 2007. The study site was located on dried flood plain dominated by sandy soils in Daxing District, southern Beijing, China. The objectives of our study were to a) qualify the dynamics of carbon, water fluxes and water-use efficiency (WUE) at an ecosystem level under various soil water conditions and b) examine the effects of environmental factors influencing WUE under different soil moisture conditions. We found that there was a significant relationship between gross ecosystem productivity (GEP) and evapotranspiratoin (ET) under different soil water. When relative extractable soil water (REW) was less than 0.1, both GEP and ET maintained at a low level and did not changed with the variation of environmental factors. GEP and ET increased as soil water contents (VWC) increase, but the greater effect of VWC on ET over GEP resulted in negative correlation between WUE and VWC when 0.1<REW<0.4. When REW was higher than 0.4, climate factors showed a significant influence on the variation of GEP and ET through stomata. Air temperature (Ta) and photosynthetically active radiation (PAR) were the main factors for the variation of GEP while air temperature (Ta) and saturated vapor pressure deficit (VPD) showed a significant effect on changes of ET. WUE decreased with the increasing VPD due to the higher sensitivity of ET to VPD than GEP. VWC was between 5.2% and 8.8% (0.1<REW<0.4) in this fast-growing poplar plantation, vegetation could utilize soil water efficiently and reached high rates of water use efficiency and carbon sequestration. We concluded that soil water condition was a key factor influencing WUE of the poplar plantation. Assessment of forest carbon sequestration and water consumption under a climate change environment must consider future precipitation regime in the study region. 参考文献 相似文献 引证文献

DEVELOPMENT AND APPLICATION OF CVA, DRIS, AND CND NORMS FOR THREE HYBRIDS OF POPULUS MAXIMOWICZII PLANTED IN SOUTHERN QUEBEC

Plantations of hybrid poplars adapted to relatively poor soils and cold conditions are being established in abandoned fields and forest sites in southern Quebec. Hybrids of Populus maximowiczii are well adapted to these sites but little is known about their nutritional requirements. The objectives of this study were to develop nutritional norms (CVA, DRIS, CND) for three of these hybrids: 915508, Populus euramericana or canadensis X Populus maximowiczii; 3729, Populus nigra X Populus maximowiczii; and 915303, Populus maximowiczii X Populus balsamifera, and to apply the norms on some sites recently planted in southern Quebec. Six plantations (two per clone) were used for the determination of nutritional norms. In each plantation, individual trees were fertilized with nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) according to a factorial design with three levels of application for each nutrient (35 = 243 treatments). Tree diameter and height, unit foliar mass and foliar chemistry (N, P, K, Ca, and Mg) of each tree were determined two years after fertilization. CVA, DRIS and CND norms were determined using a boundary-line approach with each plantation. Nutritional norms could be established for most combinations of clones and nutrients. CVA, DRIS and CND indices produced with published optimum nutrient concentrations for hybrid poplars closely related to P. maximowiczii were generally in agreement with the ones developed in our study. Differences in nutritional norms among P. maximowiczii hybrids/clones were small but hybrid/clone specific norms could provide more precise estimates of tree nutrition. The application of the norms on some representative sites of southern Quebec revealed more frequent nutrient imbalances than true nutrient deficiencies with generally excessive Ca and Mg, and limiting N, P, and K.

Microarray Analysis of Gene Expression in Triploid Black Poplar

Abstract Triploidy is a widespread phenomenon in cultivated and natural breeding plants and it can confer some growth advantages. Here, we analyzed genome-wide gene expression in triploid Populus euramericana (black poplar) using the Affymetrix poplar microarray to detect any possible correlation between triploid vigor and a unique gene expression profile. Among the 38,400 transcripts that were detected in triploid poplar, 1,564 and 2,015 genes were up- or downregulated, respectively, compared with the diploid. The majority of the upregulated genes in the triploid were associated with carbon and nitrogen metabolism, especially lignin and secondary metabolism. Other genes upregulated in the triploid included genes involved in sugar transport, and brassinosteroid (BR) and auxin metabolism. Downregulated genes were mostly related to the assembly and biosynthesis of ribosomes and the nucleosome macromolecular complex. The results suggested that BR and auxin levels were crucial in controlling sugar transport, photosynthesis and cell wall biosynthesis. Downregulated genes were associated with chromatin regulation in the triploid. The information from this analysis could provide an insight into the vigor of triploid poplar.

Comparison of some soil properties under canopy and inter-row trees in different poplar clones in North of Iran

Poplar trees are becoming extremely important as fast growing species due to the increasing need for wood and decreasing productivity of some lands in Iran. The present study aimed to find the effect of canopy of poplar clones as one of the most important effective factors on soil properties compared to the distances inter-row trees. Five poplar clones and species included: Populus euramericana triplo, P. deltoides 69/55, P. deltoides 63/51, P. euramericana 45/51 and P. caspica as native species were selected. They were planted about 18 years ago with 4×4 m spacing in frame of completely randomized block design with three replications. The soil samples were taken from 0-20 cm depth of soils under canopy of each tree and inter-row trees. The results showed the impression of the canopy on the soil properties, in a way that many physical and chemical properties of soil under the canopy and inter-row trees have significant differences. P. deltoides 63/51 clone and inter-row the trees; P. euramericana triplo clone had greater positive effects on the soil properties compared to the other clones. Our results suggested that the presence of poplar clones may be an important source of soil spatial heterogeneity.

Growth, gas exchange, root morphology and cadmium uptake responses of poplars and willows grown on cadmium-contaminated soil to elevated CO2

Little information is available about effects of elevated CO2 (EC) on growth of poplars and willows grown on Cd-contaminated soil and their potential use for Cd phytoremediation. Plant growth, gas exchange, root morphology, and Cd uptake responses to EC were assessed for one poplar genotype [Populus euramericana cv. ‘74/76’ (P107)] and two willow genotypes [Salix jiangsuensis CL. ‘799’ (J799) and Salix jiangsuensis CL. ‘172’ (J172)]. Rooted cuttings were grown on Cd-contaminated soil in six open-top chambers supplied with ambient and elevated CO2. EC increased leaf, stem, root and total biomass and total Cd uptake, but did not change Cd concentration in the tree tissues. Although stomatal conductance declined remarkably, EC stimulated leaf photosynthesis and intrinsic water use efficiency. There were differences among tree genotypes in growth and photosynthesis response to EC, with photosynthetic acclimation occurring only in P107. EC increased root lengths, root surface areas, root volumes and numbers of root tips of the three tree genotypes grown on Cd-contaminated soils. It was concluded that the biomass increase was closely correlated with stimulation of leaf photosynthesis and root growth induced by EC. EC increased the root surface areas of small-diameter roots and consequently, the ability to capture Cd in root systems, which led to increased total Cd uptake in all plant parts. The increase in total Cd uptake by the tree genotypes due to increased biomass under EC suggested an alternative way of improving the efficiency of phytoremediation of contaminated soil.

Elevated CO2 differentially affects photosynthetic induction response in two Populus species with different stomatal behavior

To understand dynamic photosynthetic characteristics in response to fluctuating light under a high CO(2) environment, we examined photosynthetic induction in two poplar genotypes from two species, Populus koreana 9 trichocarpa cv. Peace and Populus euramericana cv. I-55, respectively. Stomata of cv. Peace barely respond to changes in photosynthetic photon flux density (PFD), whereas those of cv. I-55 show a normal response to variations in PFD at ambient CO(2). The plants were grown under three CO2 regimes (380, 700, and 1,020 μmol CO(2) mol(-1) in air) for approximately 2 months. CO2 gas exchange was measured in situ in the three CO2 regimes under a sudden PFD increase from 20 to 800 μmol m(-2) s(-1). In both genotypes, plants grown under higher CO(2) conditions had a higher photosynthetic induction state, shorter induction time, and reduced induction limitation to photosynthetic carbon gain. Plants of cv. I-55 showed a much larger increase in induction state and decrease in induction time under high CO(2) regimes than did plants of cv. Peace. These showed that, throughout the whole induction process, genotype cv. I-55 had a much smaller reduction of leaf carbon gain under the two high CO(2) regimes than under the ambient CO(2) regime, while the high CO(2) effect was smaller in genotype cv. Peace. The results suggest that a high CO(2) environment can reduce both biochemical and stomatal limitations of leaf carbon gain during the photosynthetic induction process, and that a rapid stomatal response can further enhance the high CO(2) effect.

Analysis of flavonoid contents and expression of flavonoid biosynthetic genes in Populus euramericana Guinier in response to abiotic stress

Gene encoding the key flavonoid biosynthetic enzyme, chalcone synthase, in Populus euramericana Guinier (PeCHS) was cloned and characterized. PeCHS preferentially uses feruloyl- CoA as a substrate. Expression of the flavonoid biosynthetic genes, phenylalanine ammonimum lyase from P. euramericana (PePAL), PeCHS, chalcone isomerase from P. euramericana (PeCHI), and, flavonol synthase from P. euramericana (PeFLS) from P. euramericana in response to abiotic stresses such as wounding and UV-irradiation were analyzed. These genes were induced under the stress conditions. Most genes were expressed at an early stage of the stress response. In addition, total flavonoid content increased after UV-irradiation.

Research on the Measurement of Carbon Storage in Plantation Tree Trunks Based on the Carbon Storage Dynamic Analysis Method

Estimation of forest carbon storage can be of great significance to the research on the productivity of terrestrial ecosystem, carbon cycle, and global warming. China has more than 54 million hm2barren hills and waste land suitable for forestation, which provides a great potential for developing carbon sink forestry by means of forestation. This research analyzed the volume increments, volume densities, and carbon contents of 15 analytical samples of five main plantation tree species in North China, includingPinus tabulaeformis(A),Robinia pseudoacacia(B),Populus euramericana(C),Larix olgenisis(D), andLarix kaempferi(E). Results showed that carbon storage dynamic process can be expressed as follows: the ages of quantitative maturity of each tree species are 67a, 40a, 30a, 48a, 49a, respectively; the average wood densities of each tree species at different age classes are 550.93 kg/m3, 629.25 kg/m3, 404.56 kg/m3, 592.33 kg/m3, and 544.11 kg/m3,t. The average carbon contents of each tree species at different age classes are 51.48%, 46.88%, 47.81%, 46.76%, and 47.24%. It showed a significant difference between the above tree species through variance test. The maximum values of average carbon storage are 70a, 40a, 30a, 48.7a, and 49.2a, respectively. The corresponding average carbon storages are A 2.527 kg, B 3,794 kg, C 2.781 kg, D 2.996 kg, and E 3,322 kg, in a descending order ofC&gt;E&gt;D&gt;B&gt;A. This research, through experiment on four tree species with clear growth rings and one tree species with unclear growth rings, verified the scientific character and the scope of application of the carbon storage dynamic analysis method, providing a new method for the measurement and analysis of forest carbon storage.

Characterization of Hydroxycinnamoyl-coenzyme A Shikimate Hydroxycinnamoyltransferase from Populus euramericana

Hydroxycinnamoyl-coenzyme A shikimate/quinate hydroxycinnamoyltransferase (HCT), PeHCT was cloned from Populus euramericana. The predicted amino acid sequence revealed that PeHCT contained a conserved HXXXDG motif that was found in acyltransferase. The in vitro substrate was determined using recombinant PeHCT. The recombinant PeHCT showed substrate-specificity towards shikimic acid. In addition, PeHCT displayed higher expression in the stem than in the leaf, and its expression increased during the growth stage of the leaf. Results indicate PeHCT could be involved in lignin biosynthesis by formation of p-coumaroyl shikimate.

Effect of arbuscular mycorrhizal colonisation on the growth and phosphorus nutrition of Populus euramericana c.v. Ghoy

Arbuscular mycorrhizal (AM) fungi are known to associate with a range of Populus species particularly in the early stages of development yet there is little information on their potential role in sustainable biomass production. Moreover, while the AM association may enhance plant establishment, growth and nutrition, different AM fungi (AMF) vary in their ability to confer such benefits. In this study we investigated the impact of four different AMF on growth and phosphorus nutrition of Populus euramericana c.v. Ghoy. Plant biomass, particularly root biomass, was generally reduced by AMF colonisation and the extent of this reduction varied with the AMF species that had colonised the roots. This growth reduction was not simply due to differences in root colonisation, which ranged from 59 to 71% by the end of the experiment at 105 d and did not vary among the AMF screened. Phosphorus content was also lower in some AMF treatments than in non-AMF controls after growth for 105 d although P concentration in aboveground tissues (stems and leaves) was higher. The possible interaction between AMF and poplar in converted arable systems is discussed.