スギ辺材および移行材の比透過率に関与する木材組織構造

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The objective of this study was to clarify anatomical factors which determine specific permeability of sapwood and intermediate wood in air-dried sugi (Cryptomeria japonica) wood. Superficial air permeability of sugi sapwood and intermediate wood was measured and then specific permeability was determined. Using these specimens for permeability tests, the proportion of latewood and earlywood, the percentage of aspirated and incompletely aspirated pits, the number of bordered pits per tracheid, the number of tracheids per unit area and tracheid length were obtained. Specific permeability decreased with increasing levels in the stem except for the lowest level and also related to distance from pith, suggesting that cambial age is related to specific permeability. A clear relationship between percentage of latewood and specific permeability was not found, suggesting that effective pathways in earlywood determines permeability. Specific permeability of intermediate wood and sapwood were significantly related to the number of effective open pits in earlywood, Nef, which was determined by anatomical properties such as aspirated and incompletely aspirated pits, the number of pits and tracheids, and proportion of latewood, suggesting that specific permeability of sugi sapwood and intermediate wood is a physical value determined by the intrinsic properties of earlywood in addition to the condition of bordered pits.スギ辺材と移行材の比透過率を決定する木材組織構造因子を明らかにする目的で，地上高別に移行材，辺材内側と外側の比透過率を算出した。そのあと，その試験片の組織構造を計測し，比透過率との関係を見た．比透過率は樹幹上部に向かって減少，髄からの距離が大きくなるに伴って上昇する候向を示した。このことは比透過率への形成層齢の関与を示唆した．晩材割合と比透過率との問に有意な相関関係が認められなかったことから，比透過率には早材が大きな役割を担うことが明らかになった．比透過率を決定する組織構造因子として，軍材の有縁壁孔閉塞率，不完全閉塞率，仮道管当たりの有縁壁孔数，単位面積当たりの仮道管数および晩材割合を考慮して算出した有効開放壁孔数Nefが提案された．すなわち，有効開放壁孔数と比透過率との間に直線関係が認められ，スギ辺材と移行材の比透過率が，有縁壁孔の状態に加えて他の早材組織構造によって決定されることを明らかにした．
九州大学の論文

スギ辺材および移行材の比透過率に関与する木材組織構造

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