Ryogo Nakada

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Variations in carbon content in wood among 102 clones, selected from almost the entire natural distribution area, were investigated in Larix kaempferi. The average carbon content was 50.50%, 50.94%, and 50.80% in sapwood, heartwood, and whole wood, respectively. The difference in carbon content between clones was significant. The clonal repeatabilities were(More)
The genetic differentiation inherent in Zelkova serrata in Japan and the southern portion of the Korean Peninsula was examined by comparing a chloroplast DNA (cpDNA) sequence over a 16 k baselength in 40 individual samples collected from an area covering the natural distribution range of Z. serrata in Japan and the southern portion of the Korean Peninsula.(More)
Knowledge of the genetic relationship between growth traits and wood properties is critical for their simultaneous genetic improvement. We measured the height and diameter at breast height (DBH) and wood quality traits, including stress wave velocity (SWV) as the selection criteria for wood stiffness, wood density, and Pilodyn penetration depth as selection(More)
Water distribution in green stems ofCryptomeria japonica D. Don was observed by soft X-ray photography. In the sapwood, much water was present and evenly distributed. In the intermediate wood (the white zone), little water was present. The intermediate wood appeared in all cross sections of the stem and separated the heartwood from the sapwood in the(More)
Using soft X-ray photography, two-dimensional observations were made of the water distribution within the green stem ofCryptomeria japonica D. Don. Variations in the distribution pattern of the “wet area” in the horizontal plane of the lower stem were described. The distribution patterns showed extreme variation among individual trees, with broad wet-area(More)
The efficiency of the indirect selection for wood density using the Pilodyn in Cryptomeria japonica was studied by comparing the Pilodyn penetration (PP) depth and the direct measurement of wood density in three test sites. The influence of the genotype by environment (G × E) interaction of wood density was estimated using the Pilodyn with common 12 C.(More)
Wood density is an important component of wood quality, and it is therefore important to assess whether it can be subject to genetic improvement. We assessed the potential for genetic improvement of wood density in Larix kaempferi by recording components of annual growth rings. A full diallel mating test based on six plus L. kaempferi trees was used. Trees(More)
The work demonstrates a relationship between the biosynthesis of the secondary metabolite, agatharesinol, and cytological changes that occur in ray parenchyma during cell death in sapwood sticks of Cryptomeria japonica under humidity-regulated conditions. To characterize the death of ray parenchyma cells that accompanies the biosynthesis of secondary(More)
Clonal variation of flower production has been investigated thoroughly in coniferous tree species because of the importance of flowering in seed production from seed orchards. However, the inheritance of flower production by progeny test has not been previously studied well, so the heritability of male flower production of Cryptomeria japonica, the most(More)
Heartwood in tree stems provides natural durability and ornamental values to wood products as well as antimicrobial properties to protect living stems from decay. Control of the amount and quality of heartwood is required because of its importance in wood utilization. Despite the importance, the mechanism of heartwood formation has been poorly understood.(More)