Abstract:

【Objective】This study investigated the variation patterns of wood traits among the provenances and clones of Castanopsis hystrix to clarify the genetic characteristics of these traits. It provided a theoretical basis for the genetic improvement of wood traits and for the scientific processing and rational utilization of wood.【Method】The physical and chemical wood traits of 226 clones from 17 provenances in the C. hystrix germplasm bank were investigated. Twelve wood traits from different provenances and clones within those provenances were analyzed using variance analysis, and heritability was calculated based on the genetic variance of provenances and clones within provenances. Spearman correlation analysis, principal component analysis, and cluster analysis were conducted for different provenances of C. hystrix, considering geographical location and meteorological factors.【Result】Variance analysis revealed significant differences in fiber length, fiber width, wood basic density, lignin content, cellulose content and hemicellulose content among provenances. Significant differences were also observed in fiber length, fiber width, length-to-width ratio, wood basic density, fiber cavity diameter, cavity-to-diameter ratio, lignin content and hemicellulose content among clones within provenances. The heritability of wood basic density, cellulose and hemicellulose content was higher among provenances. In contrast, the heritability of the length-width ratio, fiber length, and wood basic density were higher among clones within provenances, all above 0.5, indicating that these traits were highly genetically controlled at both provenance and clonal levels. The average basic density of all provenance wood was above 0.5, indicating that C. hystrix wood was a hardwood material with high overall hardness and density. Correlation analysis results indicated that fiber length was positively correlated with wood basic density and negatively correlated with lignin content. Lignin content was negatively correlated with cellulose content, and cellulose content was negatively correlated with hemicellulose content. There is also a correlation between various source material traits and geo-climatic factors, which showed that higher longitude corresponded to higher lignin content. Higher latitude corresponds to a lower basic density of wood, and with the increase in altitude, the lignin content decreases gradually. Fiber length negatively correlated with the average annual temperature; thus, fiber length could decrease with an increase in the average annual temperature. In general, provenance was strongly correlated with geographical factors but not an obvious correlation with environmental factors. In principal component analysis, the 12 traits were integrated into six traits with significant genetic variation among provenances, and the cumulative contribution rate of the first three principal components was 62.76%, which could retain most of the information on phenotypic traits. The 17 provenances were divided into three groups using the hierarchical clustering method. Class I included six provenances characterized by low fiber length, wood basic density, vascular bundle content, and high lignin content. Class Ⅱ contained five provenances characterized by high fiber width, lignin content, cellulose content, and low fiber length and wood basic density. Class Ⅲ included six provenances characterized by high fiber length, width, wood basic density, cellulose content, and low hemicellulose content.【Conclusion】The genetic variation of the material traits in the provenances and clones of C. hystrix is rich and holds good potential for genetic improvement. Fiber length and length-width ratio should be selected as superior traits in clones during the improvement process, while wood basic density, cellulose, and hemicellulose can be improved by selection among provenances. The wood quality is mainly affected by longitude, latitude and altitude. Tree species growing in high longitude, low latitude and altitude have better wood quality. These results provide a theoretical basis for the conservation and utilization of C. hystrix germplasm resources, lay a foundation for screening clones with excellent wood quality, and offer a reference for the future improvement and breeding of C. hystrix germplasm traits.

Key words: Castanopsis hystrix, provenances, clones, woody properties, genetic variation