Analysis of synonymous codon usage in chloroplast genome of Populus alba

The pattern of codon usage in the chloroplast genome of Populus alba was investigated. Correspondence analysis （a commonly used multivariate statistical approach） and method of effective number of codons （ENc）-plot were conducted to analyze synonymous codon usage. The results of correspondence analysis showed that the distribution of genes on the major axis was significantly correlated with the frequency of use of G＋C in synonymously variable third position of sense codon （GC3S）, （r=0.349）, and the positions of genes on the axis 2 and axis 3 were significantly correlated with CAI （r=-0.348, p〈0.01 and r=0.602, p〈0.01）. The ENc for most genes was similar to that for the expected ENc based on the GC3s, but several genes with low ENc values were lying below the expected curve. All of these data indicated that codon usage was dominated by a mutational bias in chloroplast gcnome ofP. alba. The selection in nature for translational efficiency only played a minor role in shaping codon usage in the chloroplast genome ofP alba.     

Estimating the costs of one hectare of poplar planting and supplying wood required for producing various types of paper in Iran

In Iran, due to abundant restrictions on harvesting wood from northern forests by implementing the preservation project and also lack of possibility for sufficient wood production, development of the area of planting poplar is quite inevitable. Poplar wood properties have special importance to produce many wood production, particularly pulp and paper. Paper factories are the major consumers of poplar wood at the global level and this is because of unique morphological, physical, mechanical and technological properties of poplar wood. Therefore, regarding the importance of using this species in making various printing and writing paper, packaging or carton, cardboard and newsprint, in this study, costs of poplar production in one hectare including planting and harvesting were examined and determined. Then, based on conversion coefficients of FAO, required round wood, productivity and the cost of poplar wood were calculated for the producing various kinds of paper. The results indicate that carton and cardboard paper or packaging allocate the lowest cost and highest return, while printing and writing paper had highest cost and lowest return in terms of poplar wood supply needed for paper production.     

Investigation of Carbohydrate Compositions for Poplar I-214 and Chinese Fir

Carbohydrates are main compositions for wood (Menachem et al. 1991). The chemical components of poplar I-214 and Chinese fir have been reported (Huang Luohua et al. 2002; Qin Tefu et al. 2003). Through the studies of carbohydrate compositions of poplar I-214 and Chinese fir, different composition of monosaccharides can be found in both poplar I-214 and Chinese fir. 1 MATERIALS AND METHODS 1.1 Materials Wood samples of Chinese fir (Cunninghamia lancedata) and poplar I-214 (Populus…     

Stem taper equations for poplars growing on farmland in Sweden

We developed a simple polynomial taper equation for poplars growing on former farmland in Sweden and also evaluated the performance of some well-known taper equations. In Sweden there is an increasing interest in the use of poplar. Effective management of poplar plantations for high yield production would be facilitated by taper equations providing better predictions of stem volume than currently available equations. In the study a polynomial stem taper equation with five parameters was established for individual poplar trees growing on former farmland. The outputs of the polynomial taper equation were compared with five published equations. Data for fitting the equations were collected from 69 poplar trees growing at 37 stands in central and southern Sweden (lat. 55-60° N). The mean age of the stands was 21 years (range 14-43), the mean density 984 stems ha -1 (198 3,493), and the mean diameter at breast height (outside bark) 25 cm (range 12-40). To verify the tested equations, performance of accuracy and precision diameter predictions at seven points along the stem was closely analyzed. Statistics used for evaluation of the equations indicated that the variable exponent taper equation presented by Kozak (1988) performed best and can be recommended. The stem taper equation by Kozak (1988) recommended in the study is likely to be beneficial for optimising the efficiency and profitability of poplar plantation management. The constructed polynomial equation and the segmented equation presented by Max & Burkhart (1976) were second and third ranked. Due to the statistical complexity of Kozak’s equation, the constructed polynomial equation is alternatively recommended when a simple model is requested and larger bias is accepted.     

Study on Resistance of Poplars to Marssonina brunnea

PoplarisakindofgrowingquicklyspecieswithhighornaInentajandappliedvaluesisusedextensiveIyintllestreetofcitiesbotanicaIgardenandfarmprotection.Thep0pIarsarealwaysfacingthethreatsofdiseasesandinsectswI1ichcanmakethemdecIineingrowingandevendie.One0ftl1eiInpor…     

Study on resistance of poplars toMarssonina brunnea

Inoculation experiment was made for 15 poplar species to determine their resistance toMarssonina brunnea by the agar leaf-dise technique and the water-culture shoots technique. The results show thatPopulus simonii andP nigra var.thevestina are very suseeptible to the disease:P. davidiana andP. koreana are slightly resistant to the disease:P. ussurrensis has high resistance, and the others remain moderate resistance. Experiments are also made for healthy leaves to analysis the inorganic element content and water content. And the results show that the contents of Fe and Ca are remarkbly negatively related to the resistance of poplars toMarssonina brunnea. (Responsible Editor: Sun Yueqi)     

In vitro and in vivo germination of spores of Marssonina brunnea (Ell. et Ev.) P. Magn

A water soluble inhibitor of germination is present on the surfaces of freshly collected spores of Marssonina brunnea (Ell et Ev.) P. Magn. Spores of this pathogen have a high potential for germination even in the absence of external substrates. Among the poplar clones examined there was no correlation between spore germination on leaf discs and the disease reaction of the discs under controlled conditions. However under these conditions the disease development on leaf discs taken from clone I-69/55 was correlated with the high resistance of this clone to Marssonina leaf spot in the field.     

Comparaison de deux methodes ?estimation de ľinfection dejeunespeupliersparleMarssoninabrunnea(Ell. et Ev.) P. Magn.

Comparison of two methods for evaluating infection of young poplar leaves by Marssonina brunnea . Two methods for evaluating foliar infection by Marssonina brunnea have been compared on 783 twigs. They appear to be correlated. Distribution in infection classes can be coded and this allows a prediction of the number of spots per square centimeter. Application of the code to two other experiments is discussed.     

中林46杨早期落叶原因分析与治理对策

造成中林46杨早期落叶的原因主要是抗病性差，遇到特殊的气象条件，导致黑斑病严重发生。为防止早期落叶，应从营林措施入手，选育抗病良种，大力营造混交林，适时防治病虫害。     

Etude épidemiologique du Marssonina brunnea (Ell. et Ev.) P. Magn

The epidemiology of Marssonina brunnea (Ell. et Ev.) P. Magn., a leaf parasite of cultivated poplars . The relationship between outbreaks of the disease and ripening of ascospores and release of conidia in spring was studied in 1972 and 1973 in the north (Lille) and the east (Nancy) of France. During the growing season, the numbers of spores released by water splash during rainfall and also spores present in the air were systematically recorded. The various records and observations were related to climatic conditions.     

Host range and pathogenicity studies of Marsonnina brunnea to poplars

Laboratory studies of Marssonina brunnea (Ell. + Ev.) Magn. established the wide host range and strong pathogenicity of this pathogen to poplars. New Zealand isolates were uniformly pathogenic whereas gross differences in pathogenicity were observed between international isolates. The adoption of a standard inoculation technique for screening poplars for Marssonina resistance is urged.     

Ultrastructural study of the pathogenesis of Marssonina species to poplars

Studies on the pathogenesis of Marssonina brunnea, M. castagnei and M. populi to susceptible poplars showed that germtubes penetrated poplar leaves directly by enzymatic activity and indirectly through stomata. Six days following inoculation, hyphae had ramified throughout palisade and mesophyll tissues causing penetrated cells to become moribund. Acervuli were formed within seven days of inoculation and conidia were released by rupture of the cuticle and upper epidermal wall.