Research highlights: Annual wood anatomy (xylem) aids our understanding of mature wood formation and the growth strategies of trees. Background and Objectives: Catalpa bungei is an important native species in China that produces excellent quality wood. Herein, we clarified the effects of the genetic origin and cambial age on the anatomical characteristics of C. bungei wood. Materials and Methods: Six new 13-year-old C. bungei clones: ‘1-1’ (n trees = 3), ‘1-3’ (n trees = 3), ‘2-7’ (n trees = 3), ‘2-8’ (n trees = 3), ‘8-1’ (n trees = 4), and ‘9-1’ (n trees = 3) were removed for study from a plantation in Tianshui City, Gansu province, China. Xylem features were observed and the anatomical variables were manually measured via image analysis on (macro- micro-, and ultra-) features cut from radial increments of earlywood and latewood sampled at breast height. Results: Between the age of 1 and 2 years, wood was diffuse-porous; between the age of 3 and 9 years, wood was semi-ring-porous; and between the age of 10 and 13 years, wood was ring-porous. The effect of clones on anatomical characteristics was significant except for the microfibril angle in latewood and ring width. The transition between juvenile and mature wood was between 7 and 8 years based on patterns of radial variation in fiber length (earlywood) and microfibril angle. From the pith to the bark, fiber length, double wall thickness, fiber wall: lumen ratio, vessel diameter in earlywood, proportion of vessel in earlywood, and axial parenchyma in latewood increased significantly, whereas ring width, earlywood vessels, and the proportion of fiber decreased significantly. In addition, other features, such as vessel length, microfibril angle, and ray proportion, did not differ significantly from the pith to the bark. Conclusions: Breeding program must consider both clone and cambial age to improve the economic profitability of wood production.

Understanding the maturation stress and wood properties of poplar tension wood is critical for improving lumber yields and utilization ratio. In this study, the released longitudinal maturation strains (RLMS), anatomical features, physical and mechanical properties, and nano-mechanical properties of the cell wall were analyzed at different peripheral positions and heights in nine artificially inclined, 12-year-old poplar (Populus × euramericana cv. ‘Zhonglin46’) trees. The correlations between the RLMS and the wood properties were determined. The results showed that there were mixed effects of inclination on wood quality and properties. The upper sides of inclined stems had higher RLMS, proportion of G-layer, bending modulus of elasticity, and indentation modulus of the cell wall but a lower microfibril angle than the lower sides. At heights between 0.7 m and 2.2 m, only the double-wall thickness increased with height; the RLMS and other wood properties such as fiber length and basic density fluctuated or changed little with height. The RLMS were good indicators of wood properties in the tension wood area and at heights between 0.7 m and 1.5 m. The results of this study present opportunities to better understand the interactions and effects of these two phenomena, which both occur quite frequently in poplar stands and can influence the wood quality of valuable assortments.

Wood properties are crucial for the development and application of poplar clones. Here, the effects of clone and age on anatomical and chemical properties were analyzed in eight poplar clones (50, Zhonglin46, 108, 36, N179, Danhong, Sangju, and Nanyang) from Henan province, China. The results show that the effects of clone and age are both significant for these wood properties. The eight clones were grouped into three clusters according to their annual ring width, fiber quality, and chemical properties. For some properties, including annual ring width, fiber length, and microfibril angle, all clones displayed the same radial variation trends; however, for other properties, such as holocellulose content, the radial variation trends were different depending on the clones. The culmination of the mean annual increment corresponded to the turning ages of wood properties such as annual ring width in the eight clones, and holocellulose content in the partial clones except for fiber length, microfibril angle, and vessel length. The recommended rotation age of these poplar clones is 8–9 years based on the fiber quality and chemical components. These results indicate strong genetic and age control of the wood properties and highlight the rich source of variation for poplar clone selection.

Understanding maturation stress and wood properties of poplar tension wood are critical for improving lumber yields and utilization ratio. In this study, Released Longitudinal Maturation Strains (RLMS), anatomical features, physical and mechanical properties, and nano-mechanical properties of the cell wall were analyzed at different peripheral positions and heights in nine inclined, 12-year-old poplar (Populus×euramericana ‘Zhonglin46’) trees. The correlations between RLMS and wood properties were determined. The results showed that there were mixed effects of artificial inclination on wood quality and properties. The upper sides of inclined stems had higher RLMS, proportion of G-layer, bending modulus of elasticity, and elastic modulus of cell wall but lower microfibril angle than the lower sides. At heights between 0.7 m and 2.2 m, only the double wall thickness increased with height, RLMS and other wood properties such as fiber length and basic density fluctuated or changed little with height. RLMS was a good indicator of wood properties in the tension wood area and at heights between 0.7 m and 1.5 m. The results of this study present opportunities to identify and select better quality wood in poplar trees.