Abstract:

Sixty two-year-old saplings of poplar ‘Ⅰ-107’(Populus× euramericana ‘Neva’)which were divided into five groups were planted in spring and artificially inclined at the angles of 0°,15°,30°,45°and 60° from the vertical. The samples were collected from secondary xylem of the last growth ring after four months growth and separated as tension wood area(TW)and opposite wood area(OW). Then the microfibril angle, basic density and longitudinal shrinkage were analyzed. The following conclusions were drawn:1)Along with the increase of inclined angles, microfibril angle of tension wood area and opposite wood area all decreased, the values of tension wood area were smaller than those of opposite wood area. The ANOVA results revealed that there were significant effects of inclined angle and area. 2)Along with the increase of inclined angles, basic density of tension wood area increased, those of opposite wood area increased first and then decreased little. The values of tension wood area were 5.7%-14.4% bigger than those of opposite wood area. The ANOVA results revealed that there were significant effects of area; there weren't significant effects of inclined angle and the interaction between inclined angle and area.3)Along with the increase of inclined angles, longitudinal shrinkage of tension wood area increased first and then decreased later, those of opposite wood area decreased. The values of tension wood area were 1.0-2.0 times bigger than those of opposite wood area. The ANOVA results revealed that there were significant effects of area; there weren't significant effects of inclined angle and the interaction between inclined angle and area.4)For tension wood area and opposite wood area there were negative relationships between longitudinal shrinkage and microfibril angle and negative relationships between longitudinal shrinkage and basic density.

Key words: Populus×, euramericana &lsquo, Neva&rsquo, tension wood, microfibril angle, basic density, longitudinal shrinkage