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Báo cáo khoa học: "Growth stresses in tension wood: role of microfibrils and lignification"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài:"Growth stresses in tension wood: role of microfibrils and lignification. | 291 Ann Sci For 1994 51 291-300 Elsevier INRA Original article Growth stresses in tension wood role of microfibrils and lignification T Okuyama 1 H Yamamoto 1 M Yoshida 1 Y Hattori 2 RR Archer3 School of Agricultural Science Nagoya University Nagoya 464-01 2 Kagoshima University Kagoshima 890 Japan 3 Department of Civil Engineering University of Massachusetts Amherst MA 01003 USA Received 1st September 1992 accepted 18 November 1993 Summary In order to clarify the role of microfibrils in the generation of growth stresses in trees an experimental analysis was carried out on 7 Appalachian hardwood species which were with or without gelatinous fiber in the upper region of the leaning stem. In the species that had gelatinous fibers large longitudinal tensile stresses appeared in the region where the cross-sectional area of gelatinous layers were large. In the species that had no gelatinous fibers the following relationships were observed a the smaller the microfibril angle the larger the longitudinal tensile stress b the larger the tensile stress the larger the a-cellulose content c tensile stress becomes larger as crystallinity increases and d tensile growth stress had no or a slightly negative correlation with lignin content. These results suggest that the high tensile longitudinal growth stress is mainly due to the tensile stresses of cellulose microfibrils as a bundle in their axial direction. Thus the microfibrils tension hypothesis can be applied to elucidate the growth stress generation in the region of normal and tension woods. growth stress tension wood gelatinous fiber microfibril I cellulose Resume Les contraintes de croissance dans le bois de tension. Role des microfibrilles et de la lignification. Afin de clarifier le rõle ịoué paries microfibrilles dans la genèse des contraintes de crois-sance dans 1 arbre une analyse experimentale a été réalisée sur 7 essences feuillues des Appa-laches produisant OU non des fibres gelatineuses dans la partie supérieure .