Physical and mechanical properties of highland bamboo (Oldeania alpina (K.Schum.) Stapleton) landraces and culm sections growing at Banja District, Northwest Ethiopia

Abstract

Bamboo is the most versatile plant on the earth and is an important alternative construction material. Ethiopia has two native bamboo species (Oxytenanthera abyssinica and Oldeania alpina). O. alpina is the most important and widely distributed species. The landraces of this species are characterised by differing morphological and mechanical characteristics. Three O. alpina landraces in Banja district, Ethiopia, were used to investigate the effects of landraces and culm sections on the physical and mechanical properties of the culms. Nine culms from each of the three landraces were harvested to examine their physical and mechanical properties. Harvested culms were divided into three sections along the culm length, i.e., bottom, middle and top. Data were analysed with factorial two-way ANOVA and correlation tests. We conducted Tukey's honestly significant difference (HSD) test for parameters that were significant. We found an interaction effect of landraces and culm sections on moisture content and oven dry density. Culm density was highest in the top section the red landrace, followed by the top section of the black landrace, the middle section of the red landrace, the top section of the striped landrace, the middle section of the striped landrace, the bottom section of the striped landrace, the bottom section of the red landrace, the middle section of the black landrace and finally the bottom section of the black landrace. There was a significant difference in tangential and radial shrinkage between landraces and culm sections. There was also a significant interaction effect of compression strength between landraces and culm sections. The top section of the red landrace, the top section of the black landrace and the middle section of the red landrace had the highest to lowest compression strength, respectively. The effect of landrace and culm section on modulus of elasticity and modulus of rupture were significantly different. The strength of the bamboo culms was strongly correlated with their moisture contents. Moisture content was negatively correlated with compression energy, modulus of rupture and modulus of elasticity. We recommend that producers develop bamboo-based products based on their physical and mechanical properties to meet product standards.