Comparing the structure and properties of three Eucommia ulmoides wood clones based on the coefficient of variation-rank sum ratio method

Abstract

Eucommia ulmoides wood is renowned for its high quality, however, there is a lack of research regarding the assessment of its structure and properties. This gap was addressed in the present study by examining three clones of E. ulmoides [Huazhong 12 (HZ), Cili (CL), and Miye (MY)] to compare their growth and structural characteristics, chemical components, and physical and mechanical performance. We employed a comprehensive evaluation model, combining the coefficient of variation method and rank sum ratio comprehensive evaluation method, to comprehensively assess the wood samples’ structures and properties. The results reveal significant differences at the P < 0.05 level among the three clones in various parameters including tree height, ground diameter, number of internodes, cell wall area ratio, number of vessels per unit area of early and late wood, wood fiber lumen diameter and double wall thickness, fiber length and width, hemicellulose content, lignin content, air-dried density, dry shrinkage properties, wet expansion properties, compressive strength, bending strength, and bending elastic modulus. Among HZ, CL, and MY woods, CL exhibited superior development as well as physical and mechanical properties. HZ showed exceptional chemical properties, while MY demonstrated the finest cell morphology. By utilizing the proposed evaluation model, we comprehensively assessed the structures and properties of three different clones of E. ulmoides wood. All samples were categorized into upper, middle, and lower grades based on their respective characteristics. HZ was found to be distributed across all three grades, with the highest presence in the upper grade. MY was primarily distributed in the middle and lower grades; CL was predominantly found in the third grade. Among the clones, HZ showed the highest comprehensive score while MY showed the lowest score. The evaluation results indicate that among the three wood clones, HZ achieved superior quality for the fiber industry, CL and HZ are more suitable raw materials for construction industry. The findings of this study may contribute to a theoretical foundation for the selection, grading evaluation, and added value enhancement of E. ulmoides wood.