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991.
992.
Yuko Ota Megumi K. Kimura Tsutomu Hattori Yurika Miyuki Ryota Endo 《Journal of Forest Research》2016,21(2):105-109
Trunk rot, caused by Fomitiporia torreyae, is one of the most economically important sap rot diseases on Cryptomeria japonica, especially on a cutting cultivar ‘Sanbu-sugi’. This disease had been reported only from Chiba and Ibaraki prefectures in Japan; however, a similar trunk rot on Japanese cedars was found recently in Kyoto prefecture. We identified the causal agent of the trunk rot on Japanese cedars in Kyoto prefecture, clarified the genotype of ‘Sanbu-sugi’ (sensu stricto) using microsatellite markers, and then investigated the relatedness of these infected cedars with ‘Sanbu-sugi’. The pathogen was identified as F. torreyae by its DNA sequences and morphological characteristics of the fruiting body. The 25 ramets of ‘Sanbu-sugi’ had only one genotype based on eight microsatellite loci. Infected Japanese cedars in Kyoto were comprised of different genotypes and showed no close relatedness to ‘Sanbu-sugi’. This is the first report of trunk rot caused by F. torreyae on cultivars of Japanese cedar with no relatedness to ‘Sanbu-sugi’ outside of Chiba and Ibaraki prefectures and showed the potential for expansion of this disease to Japanese cedar plantations in other areas. 相似文献
993.
对河北、河南、山东、甘肃的4块毛白杨无性系测定林中约100个无性系进行了木材基本密度的测定,对木材基本密度在地点和无性系间的遗传变异进行了研究.结果表明:毛白杨无性系的木材基本密度平均值为0.4363g/cm3,木材基本密度在地点和无性系间均存在极显著差异.木材基本密度的无性系重复力为0.82~0.91,属于受遗传控制较强的材性性状.对生长和材性的相关研究表明,木材基本密度与生长性状(包括胸径、树高和材积)一般存在显著的负相关,但不同地点上表现为不同的正或负的相关关系 相似文献
994.
An experiment to examine the effect of streptobacillary arthritis on mouse populations was conducted in maturing sorghum crops
in mouse-proofed pens. There were three treatment pens and three control pens in which mice with and without clinical signs
of streptobacillary arthritis were introduced, respectively. A constant mouse density (533 mice ha−1) was introduced to the pens by releasing 12 mice in each pen. The sex ratio of introduced mice was also constant by releasing
in each pen nine males and three females. Mean track index was lower in treatment pens than in control pens, indicating that
streptobacillary arthritis reduced the activity of mice. However, this was not translated into a reduction in other population
responses. Mean mouse density at harvest, percentage of female pregnant at harvest, yield loss caused by mice and a feeding
index (oil card index) did not differ significantly between treatment and control groups. A plausible explanation for these
findings was that mice with the clinical signs might be less active but were able to consume as much grains as mice without
the clinical signs because food was in abundant supply. 相似文献
995.
Martin Häglund 《Wood Science and Technology》2007,41(6):477-490
Knowledge of effects of moisture exposure on timber structures is important for serviceability and load bearing capacity of
timber elements and systems. Varying climate affects the moisture content profiles in timber as the relative humidity changes
in the ambient air. This paper presents methods for calculation of diffusion based moisture transport and corresponding results
on how timber responds to varying moisture with regard to moisture penetration and distribution. The calculations are based
on measured outdoor relative humidity and temperature at different climatic locations in Sweden. No remarkably large deviations
between the different climatic locations were found in general, which is positive in a design code perspective. 相似文献
996.
Chang-Hua Fang Bruno Clair Joseph Gril Tancrède Alméras 《Wood Science and Technology》2007,41(8):659-671
Transverse drying shrinkage was measured at microscopic and mesoscopic levels in poplar wood characterised by an increasing
growth strain (GS), from normal to tension wood. Results show that: (a) the drying shrinkage, measured as a relative thickness
decrease, was significantly higher for G-layer (GL) than for the other layers (OL), GL shrinkage was not significantly correlated
with GS, and OL shrinkage was negatively correlated with GS. (b) In gelatinous fibre (G-fibre), lumen size increased during
drying and this increase was positively related with GS, but in normal wood fibre, lumen size decreased during drying. These
findings suggest that GL shrank outwards (i.e., its internal perimeter increases), so that its shrinkage weakly affected the
total cell shrinkage and the mesoscopic shrinkage was controlled by the OL shrinkage which shrank inwards (i.e., its external
perimeter decreases). (c) Measurements done on 7 × 7 mm2 thin sections evidenced a negative correlation between transverse
shrinkage and GS, significant in T direction but weak in R direction. These observations at both levels allow to discuss the
contribution of GL to the mesoscopic shrinkage of tension wood. 相似文献
997.
998.
We caught the adults of a secondary wood-boring insect, Callidiellum rufipenne (Motschulsky), on Japanese cedar, Cryptomeria japonica D. Don., trees and logs with manipulated bark water contents to clarify the mechanism of host selection by C. rufipenne. More C. rufipenne were trapped when the bark water content range was ca. 120–200%. Fewer C. rufipenne were trapped at higher and lower bark water contents. These findings indicate that C. rufipenne adults do not simply select weakened or dying trees. Bark water content is one of important factors for C. rufipenne choosing their host for oviposition. 相似文献
999.
1000.
This article discusses the determinants of profitability expressed as return on capital among Japanese pulp and paper companies. Return on capital is measured as income before tax related to stockholders’ equity. Return on capital has been divided into profit margin and asset utilization rate. The hypothesis is that return on capital can be explained by mill size, productivity, product line, financial situation, and use of wood resources. The dataset consists of 13 larger Japanese pulp and paper companies listed in Pulp &; Paper Statistics. Data on financial performance, production, and use of wood fibers were collected for the period 1991–2001. The average return on equity for the studied companies is 4.2%. Labor productivity has increased quite significantly, from about 600 to 1,000 kg/employee and year. An econometric analysis indicates that the best model fit is found when the asset utilization rate is used as the dependent variable. Significant variables are, among others, asset utilization rate lagged one time period (?), labor productivity (+), capital productivity (?), paper production as a share of total paper and board production (?), total value of assets on the books (?) and solidity (+). This may indicate that the total value of assets on the books is large in relation to the total production of paper, paperboard and pulp. 相似文献